@c -*-texinfo-*-
@c This is part of the GNU Emacs Lisp Reference Manual.
-@c Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1998 Free Software Foundation, Inc.
+@c Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1998, 1999, 2000, 2001,
+@c 2002, 2005 Free Software Foundation, Inc.
@c See the file elisp.texi for copying conditions.
@setfilename ../info/display
-@node Display, Calendar, System Interface, Top
+@node Display, System Interface, Processes, Top
@chapter Emacs Display
This chapter describes a number of features related to the display
@menu
* Refresh Screen:: Clearing the screen and redrawing everything on it.
-* Screen Size:: How big is the Emacs screen.
+* Forcing Redisplay:: Forcing redisplay.
* Truncation:: Folding or wrapping long text lines.
-* The Echo Area:: Where messages are displayed.
+* The Echo Area:: Displaying messages at the bottom of the screen.
+* Warnings:: Displaying warning messages for the user.
* Invisible Text:: Hiding part of the buffer text.
* Selective Display:: Hiding part of the buffer text (the old way).
-* Overlay Arrow:: Display of an arrow to indicate position.
* Temporary Displays:: Displays that go away automatically.
-* Overlays:: Use overlays to highlight parts of the buffer.
-* Width:: How wide is a character or string.
-* Faces:: A face defines a graphics appearance: font, color, etc.
+* Overlays:: Use overlays to highlight parts of the buffer.
+* Width:: How wide a character or string is on the screen.
+* Line Height:: Controlling the height of lines.
+* Faces:: A face defines a graphics style for text characters:
+ font, colors, etc.
+* Fringes:: Controlling window fringes.
+* Scroll Bars:: Controlling vertical scroll bars.
+* Pointer Shape:: Controlling the mouse pointer shape.
+* Display Property:: Enabling special display features.
+* Images:: Displaying images in Emacs buffers.
+* Buttons:: Adding clickable buttons to Emacs buffers.
* Blinking:: How Emacs shows the matching open parenthesis.
-* Inverse Video:: Specifying how the screen looks.
-* Usual Display:: The usual conventions for displaying nonprinting chars.
-* Display Tables:: How to specify other conventions.
+* Inverse Video:: Specifying how the screen looks.
+* Usual Display:: The usual conventions for displaying nonprinting chars.
+* Display Tables:: How to specify other conventions.
* Beeping:: Audible signal to the user.
* Window Systems:: Which window system is being used.
@end menu
@node Refresh Screen
@section Refreshing the Screen
-The function @code{redraw-frame} redisplays the entire contents of a
-given frame. @xref{Frames}.
+ The function @code{redraw-frame} clears and redisplays the entire
+contents of a given frame (@pxref{Frames}). This is useful if the
+screen is corrupted.
@c Emacs 19 feature
@defun redraw-frame frame
This function clears and redisplays frame @var{frame}.
@end defun
-Even more powerful is @code{redraw-display}:
+ Even more powerful is @code{redraw-display}:
@deffn Command redraw-display
This function clears and redisplays all visible frames.
@end deffn
+ This function calls for redisplay of certain windows, the next time
+redisplay is done, but does not clear them first.
+
+@defun force-window-update &optional object
+This function forces redisplay of some or all windows. If
+@var{object} is a window, it forces redisplay of that window. If
+@var{object} is a buffer or buffer name, it forces redisplay of all
+windows displaying that buffer. If @var{object} is @code{nil} (or
+omitted), it forces redisplay of all windows.
+@end defun
+
Processing user input takes absolute priority over redisplay. If you
call these functions when input is available, they do nothing
immediately, but a full redisplay does happen eventually---after all the
@cindex resume (cf. @code{no-redraw-on-reenter})
This variable controls whether Emacs redraws the entire screen after it
has been suspended and resumed. Non-@code{nil} means there is no need
-to redraw, @code{nil} means redrawing is needed.
+to redraw, @code{nil} means redrawing is needed. The default is @code{nil}.
@end defvar
-@node Screen Size
-@section Screen Size
-@cindex size of screen
-@cindex screen size
-@cindex display lines
-@cindex display columns
-@cindex resize redisplay
+@node Forcing Redisplay
+@section Forcing Redisplay
+@cindex forcing redisplay
- The screen size functions access or specify the height or width of
-the terminal. When you are using multiple frames, they apply to the
-selected frame (@pxref{Frames}).
+ Emacs redisplay normally stops if input arrives, and does not happen
+at all if input is available before it starts. Most of the time, this
+is exactly what you want. However, you can prevent preemption by
+binding @code{redisplay-dont-pause} to a non-@code{nil} value.
-@defun screen-height
-This function returns the number of lines on the screen that are
-available for display.
-
-@example
-@group
-(screen-height)
- @result{} 50
-@end group
-@end example
-@end defun
+@tindex redisplay-dont-pause
+@defvar redisplay-dont-pause
+If this variable is non-@code{nil}, pending input does not
+prevent or halt redisplay; redisplay occurs, and finishes,
+regardless of whether input is available.
+@end defvar
-@defun screen-width
-This function returns the number of columns on the screen that are
-available for display.
+ You can request a display update, but only if no input is pending,
+with @code{(sit-for 0)}. To force a display update even when input is
+pending, do this:
@example
-@group
-(screen-width)
- @result{} 80
-@end group
+(let ((redisplay-dont-pause t))
+ (sit-for 0))
@end example
-@end defun
-
-@defun set-screen-height lines &optional not-actual-size
-This function declares that the terminal can display @var{lines} lines.
-The sizes of existing windows are altered proportionally to fit.
-
-If @var{not-actual-size} is non-@code{nil}, then Emacs displays
-@var{lines} lines of output, but does not change its value for the
-actual height of the screen. (Knowing the correct actual size may be
-necessary for correct cursor positioning.) Using a smaller height than
-the terminal actually implements may be useful to reproduce behavior
-observed on a smaller screen, or if the terminal malfunctions when using
-its whole screen.
-
-If @var{lines} is different from what it was previously, then the
-entire screen is cleared and redisplayed using the new size.
-
-This function returns @code{nil}.
-@end defun
-
-@defun set-screen-width columns &optional not-actual-size
-This function declares that the terminal can display @var{columns}
-columns. The details are as in @code{set-screen-height}.
-@end defun
@node Truncation
@section Truncation
one screen line. The additional screen lines used to display a long
text line are called @dfn{continuation} lines. Normally, a @samp{$} in
the rightmost column of the window indicates truncation; a @samp{\} on
-the rightmost column indicates a line that ``wraps'' or is continued
-onto the next line. (The display table can specify alternative
-indicators; see @ref{Display Tables}.)
+the rightmost column indicates a line that ``wraps'' onto the next line,
+which is also called @dfn{continuing} the line. (The display table can
+specify alternative indicators; see @ref{Display Tables}.)
+
+ On a window system display, the @samp{$} and @samp{\} indicators are
+replaced with arrow images displayed in the window fringes
+(@pxref{Fringes}).
Note that continuation is different from filling; continuation happens
on the screen only, not in the buffer contents, and it breaks a line
@defopt default-truncate-lines
This variable is the default value for @code{truncate-lines}, for
-buffers that do not have local values for it.
+buffers that do not have buffer-local values for it.
@end defopt
@defopt truncate-partial-width-windows
@code{truncate-lines} says what to do with them.
@end defopt
- You can override the glyphs that indicate continuation or truncation
-using the display table; see @ref{Display Tables}.
+ When horizontal scrolling (@pxref{Horizontal Scrolling}) is in use in
+a window, that forces truncation.
- If your buffer contains @strong{very} long lines, and you use
+ If your buffer contains @emph{very} long lines, and you use
continuation to display them, just thinking about them can make Emacs
redisplay slow. The column computation and indentation functions also
become slow. Then you might find it advisable to set
Turning on the cache slows down processing of short lines somewhat.
-This variable is automatically local in every buffer.
+This variable is automatically buffer-local in every buffer.
@end defvar
@node The Echo Area
@cindex error display
@cindex echo area
-The @dfn{echo area} is used for displaying messages made with the
-@code{message} primitive, and for echoing keystrokes. It is not the
-same as the minibuffer, despite the fact that the minibuffer appears
-(when active) in the same place on the screen as the echo area. The
-@cite{GNU Emacs Manual} specifies the rules for resolving conflicts
-between the echo area and the minibuffer for use of that screen space
-(@pxref{Minibuffer,, The Minibuffer, emacs, The GNU Emacs Manual}).
-Error messages appear in the echo area; see @ref{Errors}.
+ The @dfn{echo area} is used for displaying error messages
+(@pxref{Errors}), for messages made with the @code{message} primitive,
+and for echoing keystrokes. It is not the same as the minibuffer,
+despite the fact that the minibuffer appears (when active) in the same
+place on the screen as the echo area. The @cite{GNU Emacs Manual}
+specifies the rules for resolving conflicts between the echo area and
+the minibuffer for use of that screen space (@pxref{Minibuffer,, The
+Minibuffer, emacs, The GNU Emacs Manual}).
+
+ You can write output in the echo area by using the Lisp printing
+functions with @code{t} as the stream (@pxref{Output Functions}), or
+explicitly.
+
+@menu
+* Displaying Messages:: Explicitly displaying text in the echo area.
+* Progress:: Informing user about progress of a long operation.
+* Logging Messages:: Echo area messages are logged for the user.
+* Echo Area Customization:: Controlling the echo area.
+@end menu
-You can write output in the echo area by using the Lisp printing
-functions with @code{t} as the stream (@pxref{Output Functions}), or as
-follows:
+@node Displaying Messages
+@subsection Displaying Messages in the Echo Area
+
+ This section describes the functions for explicitly producing echo
+area messages. Many other Emacs features display messages there, too.
@defun message string &rest arguments
-This function displays a one-line message in the echo area. The
+This function displays a message in the echo area. The
argument @var{string} is similar to a C language @code{printf} control
-string. See @code{format} in @ref{String Conversion}, for the details
+string. See @code{format} in @ref{Formatting Strings}, for the details
on the conversion specifications. @code{message} returns the
constructed string.
In batch mode, @code{message} prints the message text on the standard
error stream, followed by a newline.
+If @var{string}, or strings among the @var{arguments}, have @code{face}
+text properties, these affect the way the message is displayed.
+
@c Emacs 19 feature
-If @var{string} is @code{nil}, @code{message} clears the echo area. If
-the minibuffer is active, this brings the minibuffer contents back onto
-the screen immediately.
+If @var{string} is @code{nil}, @code{message} clears the echo area; if
+the echo area has been expanded automatically, this brings it back to
+its normal size. If the minibuffer is active, this brings the
+minibuffer contents back onto the screen immediately.
@example
@group
---------- Echo Area ----------
@end group
@end example
+
+To automatically display a message in the echo area or in a pop-buffer,
+depending on its size, use @code{display-message-or-buffer} (see below).
+@end defun
+
+@tindex with-temp-message
+@defmac with-temp-message message &rest body
+This construct displays a message in the echo area temporarily, during
+the execution of @var{body}. It displays @var{message}, executes
+@var{body}, then returns the value of the last body form while restoring
+the previous echo area contents.
+@end defmac
+
+@defun message-or-box string &rest arguments
+This function displays a message like @code{message}, but may display it
+in a dialog box instead of the echo area. If this function is called in
+a command that was invoked using the mouse---more precisely, if
+@code{last-nonmenu-event} (@pxref{Command Loop Info}) is either
+@code{nil} or a list---then it uses a dialog box or pop-up menu to
+display the message. Otherwise, it uses the echo area. (This is the
+same criterion that @code{y-or-n-p} uses to make a similar decision; see
+@ref{Yes-or-No Queries}.)
+
+You can force use of the mouse or of the echo area by binding
+@code{last-nonmenu-event} to a suitable value around the call.
+@end defun
+
+@defun message-box string &rest arguments
+This function displays a message like @code{message}, but uses a dialog
+box (or a pop-up menu) whenever that is possible. If it is impossible
+to use a dialog box or pop-up menu, because the terminal does not
+support them, then @code{message-box} uses the echo area, like
+@code{message}.
+@end defun
+
+@defun display-message-or-buffer message &optional buffer-name not-this-window frame
+@tindex display-message-or-buffer
+This function displays the message @var{message}, which may be either a
+string or a buffer. If it is shorter than the maximum height of the
+echo area, as defined by @code{max-mini-window-height}, it is displayed
+in the echo area, using @code{message}. Otherwise,
+@code{display-buffer} is used to show it in a pop-up buffer.
+
+Returns either the string shown in the echo area, or when a pop-up
+buffer is used, the window used to display it.
+
+If @var{message} is a string, then the optional argument
+@var{buffer-name} is the name of the buffer used to display it when a
+pop-up buffer is used, defaulting to @samp{*Message*}. In the case
+where @var{message} is a string and displayed in the echo area, it is
+not specified whether the contents are inserted into the buffer anyway.
+
+The optional arguments @var{not-this-window} and @var{frame} are as for
+@code{display-buffer}, and only used if a buffer is displayed.
@end defun
-@tindex current-message
@defun current-message
This function returns the message currently being displayed in the
echo area, or @code{nil} if there is none.
@end defun
-@tindex echo-area-clear-hook
-@defvar echo-area-clear-hook
-This normal hook is run whenever the echo area is cleared---either by
-@code{(message nil)} or for any other reason.
-@end defvar
+@node Progress
+@subsection Reporting Operation Progress
+@cindex progress reporting
+
+ When an operation can take a while to finish, you should inform the
+user about the progress it makes. This way the user can estimate
+remaining time and clearly see that Emacs is busy working, not hung.
+
+ Functions listed in this section provide simple and efficient way of
+reporting operation progress. Here is a working example that does
+nothing useful:
+
+@smallexample
+(let ((progress-reporter
+ (make-progress-reporter "Collecting mana for Emacs..."
+ 0 500)))
+ (dotimes (k 500)
+ (sit-for 0.01)
+ (progress-reporter-update progress-reporter k))
+ (progress-reporter-done progress-reporter))
+@end smallexample
+
+@defun make-progress-reporter message min-value max-value &optional current-value min-change min-time
+This function creates and returns a @dfn{progress reporter}---an
+object you will use as an argument for all other functions listed
+here. The idea is to precompute as much data as possible to make
+progress reporting very fast.
+
+When this progress reporter is subsequently used, it will display
+@var{message} in the echo area, followed by progress percentage.
+@var{message} is treated as a simple string. If you need it to depend
+on a filename, for instance, use @code{format} before calling this
+function.
+
+@var{min-value} and @var{max-value} arguments stand for starting and
+final states of your operation. For instance, if you scan a buffer,
+they should be the results of @code{point-min} and @code{point-max}
+correspondingly. It is required that @var{max-value} is greater than
+@var{min-value}. If you create progress reporter when some part of
+the operation has already been completed, then specify
+@var{current-value} argument. But normally you should omit it or set
+it to @code{nil}---it will default to @var{min-value} then.
+
+Remaining arguments control the rate of echo area updates. Progress
+reporter will wait for at least @var{min-change} more percents of the
+operation to be completed before printing next message.
+@var{min-time} specifies the minimum time in seconds to pass between
+successive prints. It can be fractional. Depending on Emacs and
+system capabilities, progress reporter may or may not respect this
+last argument or do it with varying precision. Default value for
+@var{min-change} is 1 (one percent), for @var{min-time}---0.2
+(seconds.)
+
+This function calls @code{progress-reporter-update}, so the first
+message is printed immediately.
+@end defun
+
+@defun progress-reporter-update reporter value
+This function does the main work of reporting progress of your
+operation. It displays the message of @var{reporter}, followed by
+progress percentage determined by @var{value}. If percentage is zero,
+or close enough according to the @var{min-change} and @var{min-time}
+arguments, then it is omitted from the output.
+
+@var{reporter} must be the result of a call to
+@code{make-progress-reporter}. @var{value} specifies the current
+state of your operation and must be between @var{min-value} and
+@var{max-value} (inclusive) as passed to
+@code{make-progress-reporter}. For instance, if you scan a buffer,
+then @var{value} should be the result of a call to @code{point}.
+
+This function respects @var{min-change} and @var{min-time} as passed
+to @code{make-progress-reporter} and so does not output new messages
+on every invocation. It is thus very fast and normally you should not
+try to reduce the number of calls to it: resulting overhead will most
+likely negate your effort.
+@end defun
-Almost all the messages displayed in the echo area are also recorded
-in the @samp{*Messages*} buffer.
+@defun progress-reporter-force-update reporter value &optional new-message
+This function is similar to @code{progress-reporter-update} except
+that it prints a message in the echo area unconditionally.
+
+The first two arguments have the same meaning as for
+@code{progress-reporter-update}. Optional @var{new-message} allows
+you to change the message of the @var{reporter}. Since this functions
+always updates the echo area, such a change will be immediately
+presented to the user.
+@end defun
+
+@defun progress-reporter-done reporter
+This function should be called when the operation is finished. It
+prints the message of @var{reporter} followed by word ``done'' in the
+echo area.
+
+You should always call this function and not hope for
+@code{progress-reporter-update} to print ``100%.'' Firstly, it may
+never print it, there are many good reasons for this not to happen.
+Secondly, ``done'' is more explicit.
+@end defun
+
+@defmac dotimes-with-progress-reporter (var count [result]) message body...
+This is a convenience macro that works the same way as @code{dotimes}
+does, but also reports loop progress using the functions described
+above. It allows you to save some typing.
+
+You can rewrite the example in the beginning of this node using
+this macro this way:
+
+@example
+(dotimes-with-progress-reporter
+ (k 500)
+ "Collecting some mana for Emacs..."
+ (sit-for 0.01))
+@end example
+@end defmac
+
+@node Logging Messages
+@subsection Logging Messages in @samp{*Messages*}
+@cindex logging echo-area messages
+
+ Almost all the messages displayed in the echo area are also recorded
+in the @samp{*Messages*} buffer so that the user can refer back to
+them. This includes all the messages that are output with
+@code{message}.
@defopt message-log-max
This variable specifies how many lines to keep in the @samp{*Messages*}
@end example
@end defopt
-@defvar echo-keystrokes
-This variable determines how much time should elapse before command
-characters echo. Its value must be an integer, which specifies the
-number of seconds to wait before echoing. If the user types a prefix
-key (such as @kbd{C-x}) and then delays this many seconds before
-continuing, the prefix key is echoed in the echo area. Any subsequent
-characters in the same command will be echoed as well.
+ To make @samp{*Messages*} more convenient for the user, the logging
+facility combines successive identical messages. It also combines
+successive related messages for the sake of two cases: question
+followed by answer, and a series of progress messages.
-If the value is zero, then command input is not echoed.
-@end defvar
+ A ``question followed by an answer'' means two messages like the
+ones produced by @code{y-or-n-p}: the first is @samp{@var{question}},
+and the second is @samp{@var{question}...@var{answer}}. The first
+message conveys no additional information beyond what's in the second,
+so logging the second message discards the first from the log.
+
+ A ``series of progress messages'' means successive messages like
+those produced by @code{make-progress-reporter}. They have the form
+@samp{@var{base}...@var{how-far}}, where @var{base} is the same each
+time, while @var{how-far} varies. Logging each message in the series
+discards the previous one, provided they are consecutive.
+
+ The functions @code{make-progress-reporter} and @code{y-or-n-p}
+don't have to do anything special to activate the message log
+combination feature. It operates whenever two consecutive messages
+are logged that share a common prefix ending in @samp{...}.
+
+@node Echo Area Customization
+@subsection Echo Area Customization
+
+ These variables control details of how the echo area works.
@defvar cursor-in-echo-area
This variable controls where the cursor appears when a message is
for brief periods of time.
@end defvar
+@defvar echo-area-clear-hook
+This normal hook is run whenever the echo area is cleared---either by
+@code{(message nil)} or for any other reason.
+@end defvar
+
+@defvar echo-keystrokes
+This variable determines how much time should elapse before command
+characters echo. Its value must be an integer or floating point number,
+which specifies the
+number of seconds to wait before echoing. If the user types a prefix
+key (such as @kbd{C-x}) and then delays this many seconds before
+continuing, the prefix key is echoed in the echo area. (Once echoing
+begins in a key sequence, all subsequent characters in the same key
+sequence are echoed immediately.)
+
+If the value is zero, then command input is not echoed.
+@end defvar
+
+@defopt max-mini-window-height
+This variable specifies the maximum height for resizing minibuffer
+windows. If a float, it specifies a fraction of the height of the
+frame. If an integer, it specifies a number of lines.
+@end defopt
+
+@defvar message-truncate-lines
+Normally, displaying a long message resizes the echo area to display
+the entire message. But if the variable @code{message-truncate-lines}
+is non-@code{nil}, the echo area does not resize, and the message is
+truncated to fit it, as in Emacs 20 and before.
+@end defvar
+
+@node Warnings
+@section Reporting Warnings
+@cindex warnings
+
+ @dfn{Warnings} are a facility for a program to inform the user of a
+possible problem, but continue running.
+
+@menu
+* Warning Basics:: Warnings concepts and functions to report them.
+* Warning Variables:: Variables programs bind to customize their warnings.
+* Warning Options:: Variables users set to control display of warnings.
+@end menu
+
+@node Warning Basics
+@subsection Warning Basics
+@cindex severity level
+
+ Every warning has a textual message, which explains the problem for
+the user, and a @dfn{severity level} which is a symbol. Here are the
+possible severity levels, in order of decreasing severity, and their
+meanings:
+
+@table @code
+@item :emergency
+A problem that will seriously impair Emacs operation soon
+if you do not attend to it promptly.
+@item :error
+A report of data or circumstances that are inherently wrong.
+@item :warning
+A report of data or circumstances that are not inherently wrong, but
+raise suspicion of a possible problem.
+@item :debug
+A report of information that may be useful if you are debugging.
+@end table
+
+ When your program encounters invalid input data, it can either
+signal a Lisp error by calling @code{error} or @code{signal} or report
+a warning with severity @code{:error}. Signaling a Lisp error is the
+easiest thing to do, but it means the program cannot continue
+processing. If you want to take the trouble to implement a way to
+continue processing despite the bad data, then reporting a warning of
+severity @code{:error} is the right way to inform the user of the
+problem. For instance, the Emacs Lisp byte compiler can report an
+error that way and continue compiling other functions. (If the
+program signals a Lisp error and then handles it with
+@code{condition-case}, the user won't see the error message; it could
+show the message to the user by reporting it as a warning.)
+
+@cindex warning type
+ Each warning has a @dfn{warning type} to classify it. The type is a
+list of symbols. The first symbol should be the custom group that you
+use for the program's user options. For example, byte compiler
+warnings use the warning type @code{(bytecomp)}. You can also
+subcategorize the warnings, if you wish, by using more symbols in the
+list.
+
+@defun display-warning type message &optional level buffer-name
+This function reports a warning, using @var{message} as the message
+and @var{type} as the warning type. @var{level} should be the
+severity level, with @code{:warning} being the default.
+
+@var{buffer-name}, if non-@code{nil}, specifies the name of the buffer
+for logging the warning. By default, it is @samp{*Warnings*}.
+@end defun
+
+@defun lwarn type level message &rest args
+This function reports a warning using the value of @code{(format
+@var{message} @var{args}...)} as the message. In other respects it is
+equivalent to @code{display-warning}.
+@end defun
+
+@defun warn message &rest args
+This function reports a warning using the value of @code{(format
+@var{message} @var{args}...)} as the message, @code{(emacs)} as the
+type, and @code{:warning} as the severity level. It exists for
+compatibility only; we recommend not using it, because you should
+specify a specific warning type.
+@end defun
+
+@node Warning Variables
+@subsection Warning Variables
+
+ Programs can customize how their warnings appear by binding
+the variables described in this section.
+
+@defvar warning-levels
+This list defines the meaning and severity order of the warning
+severity levels. Each element defines one severity level,
+and they are arranged in order of decreasing severity.
+
+Each element has the form @code{(@var{level} @var{string}
+@var{function})}, where @var{level} is the severity level it defines.
+@var{string} specifies the textual description of this level.
+@var{string} should use @samp{%s} to specify where to put the warning
+type information, or it can omit the @samp{%s} so as not to include
+that information.
+
+The optional @var{function}, if non-@code{nil}, is a function to call
+with no arguments, to get the user's attention.
+
+Normally you should not change the value of this variable.
+@end defvar
+
+@defvar warning-prefix-function
+If non-@code{nil}, the value is a function to generate prefix text for
+warnings. Programs can bind the variable to a suitable function.
+@code{display-warning} calls this function with the warnings buffer
+current, and the function can insert text in it. That text becomes
+the beginning of the warning message.
+
+The function is called with two arguments, the severity level and its
+entry in @code{warning-levels}. It should return a list to use as the
+entry (this value need not be an actual member of
+@code{warning-levels}). By constructing this value, the function can
+change the severity of the warning, or specify different handling for
+a given severity level.
+
+If the variable's value is @code{nil} then there is no function
+to call.
+@end defvar
+
+@defvar warning-series
+Programs can bind this variable to @code{t} to say that the next
+warning should begin a series. When several warnings form a series,
+that means to leave point on the first warning of the series, rather
+than keep moving it for each warning so that it appears on the last one.
+The series ends when the local binding is unbound and
+@code{warning-series} becomes @code{nil} again.
+
+The value can also be a symbol with a function definition. That is
+equivalent to @code{t}, except that the next warning will also call
+the function with no arguments with the warnings buffer current. The
+function can insert text which will serve as a header for the series
+of warnings.
+
+Once a series has begun, the value is a marker which points to the
+buffer position in the warnings buffer of the start of the series.
+
+The variable's normal value is @code{nil}, which means to handle
+each warning separately.
+@end defvar
+
+@defvar warning-fill-prefix
+When this variable is non-@code{nil}, it specifies a fill prefix to
+use for filling each warning's text.
+@end defvar
+
+@defvar warning-type-format
+This variable specifies the format for displaying the warning type
+in the warning message. The result of formatting the type this way
+gets included in the message under the control of the string in the
+entry in @code{warning-levels}. The default value is @code{" (%s)"}.
+If you bind it to @code{""} then the warning type won't appear at
+all.
+@end defvar
+
+@node Warning Options
+@subsection Warning Options
+
+ These variables are used by users to control what happens
+when a Lisp program reports a warning.
+
+@defopt warning-minimum-level
+This user option specifies the minimum severity level that should be
+shown immediately to the user. The default is @code{:warning}, which
+means to immediately display all warnings except @code{:debug}
+warnings.
+@end defopt
+
+@defopt warning-minimum-log-level
+This user option specifies the minimum severity level that should be
+logged in the warnings buffer. The default is @code{:warning}, which
+means to log all warnings except @code{:debug} warnings.
+@end defopt
+
+@defopt warning-suppress-types
+This list specifies which warning types should not be displayed
+immediately for the user. Each element of the list should be a list
+of symbols. If its elements match the first elements in a warning
+type, then that warning is not displayed immediately.
+@end defopt
+
+@defopt warning-suppress-log-types
+This list specifies which warning types should not be logged in the
+warnings buffer. Each element of the list should be a list of
+symbols. If it matches the first few elements in a warning type, then
+that warning is not logged.
+@end defopt
+
@node Invisible Text
@section Invisible Text
@cindex invisible text
You can make characters @dfn{invisible}, so that they do not appear on
the screen, with the @code{invisible} property. This can be either a
-text property or a property of an overlay.
+text property (@pxref{Text Properties}) or a property of an overlay
+(@pxref{Overlays}). Cursor motion also partly ignores these
+characters; if the command loop finds point within them, it moves
+point to the other side of them.
In the simplest case, any non-@code{nil} @code{invisible} property makes
a character invisible. This is the default case---if you don't alter
the default value of @code{buffer-invisibility-spec}, this is how the
-@code{invisibility} property works. This feature is much like selective
-display (@pxref{Selective Display}), but more general and cleaner.
+@code{invisible} property works. You should normally use @code{t}
+as the value of the @code{invisible} property if you don't plan
+to set @code{buffer-invisibility-spec} yourself.
More generally, you can use the variable @code{buffer-invisibility-spec}
to control which values of the @code{invisible} property make text
value of @code{buffer-invisibility-spec}.
Controlling visibility with @code{buffer-invisibility-spec} is
-especially useful in a program to display the list of entries in a data
-base. It permits the implementation of convenient filtering commands to
-view just a part of the entries in the data base. Setting this variable
-is very fast, much faster than scanning all the text in the buffer
-looking for properties to change.
+especially useful in a program to display the list of entries in a
+database. It permits the implementation of convenient filtering
+commands to view just a part of the entries in the database. Setting
+this variable is very fast, much faster than scanning all the text in
+the buffer looking for properties to change.
@defvar buffer-invisibility-spec
This variable specifies which kinds of @code{invisible} properties
-actually make a character invisible.
+actually make a character invisible. Setting this variable makes it
+buffer-local.
@table @asis
@item @code{t}
non-@code{nil}. This is the default.
@item a list
-Each element of the list makes certain characters invisible.
-Ultimately, a character is invisible if any of the elements of this list
-applies to it. The list can have two kinds of elements:
+Each element of the list specifies a criterion for invisibility; if a
+character's @code{invisible} property fits any one of these criteria,
+the character is invisible. The list can have two kinds of elements:
@table @code
@item @var{atom}
-A character is invisible if its @code{invisible} propery value
+A character is invisible if its @code{invisible} property value
is @var{atom} or if it is a list with @var{atom} as a member.
@item (@var{atom} . t)
-A character is invisible if its @code{invisible} propery value
+A character is invisible if its @code{invisible} property value
is @var{atom} or if it is a list with @var{atom} as a member.
Moreover, if this character is at the end of a line and is followed
by a visible newline, it displays an ellipsis.
Two functions are specifically provided for adding elements to
@code{buffer-invisibility-spec} and removing elements from it.
-@tindex add-to-invisibility-spec
@defun add-to-invisibility-spec element
-Add the element @var{element} to @code{buffer-invisibility-spec}
-(if it is not already present in that list).
+This function adds the element @var{element} to
+@code{buffer-invisibility-spec}. If @code{buffer-invisibility-spec}
+was @code{t}, it changes to a list, @code{(t)}, so that text whose
+@code{invisible} property is @code{t} remains invisible.
@end defun
-@tindex remove-from-invisibility-spec
@defun remove-from-invisibility-spec element
-Remove the element @var{element} from @code{buffer-invisibility-spec}.
+This removes the element @var{element} from
+@code{buffer-invisibility-spec}. This does nothing if @var{element}
+is not in the list.
@end defun
- One convention about the use of @code{buffer-invisibility-spec} is
-that a major mode should use the mode's own name as an element of
-@code{buffer-invisibility-spec} and as the value of the @code{invisible}
-property:
+ A convention for use of @code{buffer-invisibility-spec} is that a
+major mode should use the mode's own name as an element of
+@code{buffer-invisibility-spec} and as the value of the
+@code{invisible} property:
@example
-;; If we want to display an ellipsis:
-(add-to-invisibility-spec '(my-symbol . t))
-;; If you don't want ellipsis:
-(add-to-invisibility-spec 'my-symbol)
+;; @r{If you want to display an ellipsis:}
+(add-to-invisibility-spec '(my-symbol . t))
+;; @r{If you don't want ellipsis:}
+(add-to-invisibility-spec 'my-symbol)
(overlay-put (make-overlay beginning end)
'invisible 'my-symbol)
-;; When done with the overlays:
+;; @r{When done with the overlays:}
(remove-from-invisibility-spec '(my-symbol . t))
-;; Or respectively:
+;; @r{Or respectively:}
(remove-from-invisibility-spec 'my-symbol)
@end example
@vindex line-move-ignore-invisible
- Ordinarily, commands that operate on text or move point do not care
+ Ordinarily, functions that operate on text or move point do not care
whether the text is invisible. The user-level line motion commands
explicitly ignore invisible newlines if
-@code{line-move-ignore-invisible} is non-@code{nil}, but only because
-they are explicitly programmed to do so.
+@code{line-move-ignore-invisible} is non-@code{nil} (the default), but
+only because they are explicitly programmed to do so.
+
+ However, if a command ends with point inside or immediately after
+invisible text, the main editing loop moves point further forward or
+further backward (in the same direction that the command already moved
+it) until that condition is no longer true. Thus, if the command
+moved point back into an invisible range, Emacs moves point back to
+the beginning of that range, following the previous visible character.
+If the command moved point forward into an invisible range, Emacs
+moves point forward past the first visible character that follows the
+invisible text.
Incremental search can make invisible overlays visible temporarily
and/or permanently when a match includes invisible text. To enable
During the search, such overlays are made temporarily visible by
temporarily modifying their invisible and intangible properties. If you
-want this to be done differently for a certain overlays, give it a
+want this to be done differently for a certain overlay, give it an
@code{isearch-open-invisible-temporary} property which is a function.
The function is called with two arguments: the first is the overlay, and
-the second is @code{nil} to make the overlay visible or @code{t} to make
-it invisible again.
+the second is @code{nil} to make the overlay visible, or @code{t} to
+make it invisible again.
@node Selective Display
@section Selective Display
@cindex selective display
- @dfn{Selective display} is a pair of features that hide certain
-lines on the screen.
+ @dfn{Selective display} refers to a pair of related features for
+hiding certain lines on the screen.
- The first variant, explicit selective display, is designed for use in
-a Lisp program. The program controls which lines are hidden by altering
-the text. Outline mode has traditionally used this variant. It has
-been partially replaced by the invisible text feature (@pxref{Invisible
-Text}); there is a new version of Outline mode which uses that instead.
+ The first variant, explicit selective display, is designed for use
+in a Lisp program: it controls which lines are hidden by altering the
+text. This kind of hiding in some ways resembles the effect of the
+@code{invisible} property (@pxref{Invisible Text}), but the two
+features are different and do not work the same way.
In the second variant, the choice of lines to hide is made
automatically based on indentation. This variant is designed to be a
The way you control explicit selective display is by replacing a
newline (control-j) with a carriage return (control-m). The text that
-was formerly a line following that newline is now invisible. Strictly
-speaking, it is temporarily no longer a line at all, since only newlines
-can separate lines; it is now part of the previous line.
+was formerly a line following that newline is now hidden. Strictly
+speaking, it is temporarily no longer a line at all, since only
+newlines can separate lines; it is now part of the previous line.
Selective display does not directly affect editing commands. For
-example, @kbd{C-f} (@code{forward-char}) moves point unhesitatingly into
-invisible text. However, the replacement of newline characters with
-carriage return characters affects some editing commands. For example,
-@code{next-line} skips invisible lines, since it searches only for
-newlines. Modes that use selective display can also define commands
-that take account of the newlines, or that make parts of the text
-visible or invisible.
+example, @kbd{C-f} (@code{forward-char}) moves point unhesitatingly
+into hidden text. However, the replacement of newline characters with
+carriage return characters affects some editing commands. For
+example, @code{next-line} skips hidden lines, since it searches only
+for newlines. Modes that use selective display can also define
+commands that take account of the newlines, or that control which
+parts of the text are hidden.
When you write a selectively displayed buffer into a file, all the
control-m's are output as newlines. This means that when you next read
-in the file, it looks OK, with nothing invisible. The selective display
+in the file, it looks OK, with nothing hidden. The selective display
effect is seen only within Emacs.
@defvar selective-display
This buffer-local variable enables selective display. This means that
-lines, or portions of lines, may be made invisible.
+lines, or portions of lines, may be made hidden.
@itemize @bullet
@item
-If the value of @code{selective-display} is @code{t}, then any portion
-of a line that follows a control-m is not displayed.
+If the value of @code{selective-display} is @code{t}, then the character
+control-m marks the start of hidden text; the control-m, and the rest
+of the line following it, are not displayed. This is explicit selective
+display.
@item
If the value of @code{selective-display} is a positive integer, then
displayed.
@end itemize
-When some portion of a buffer is invisible, the vertical movement
+When some portion of a buffer is hidden, the vertical movement
commands operate as if that portion did not exist, allowing a single
-@code{next-line} command to skip any number of invisible lines.
+@code{next-line} command to skip any number of hidden lines.
However, character movement commands (such as @code{forward-char}) do
-not skip the invisible portion, and it is possible (if tricky) to insert
-or delete text in an invisible portion.
+not skip the hidden portion, and it is possible (if tricky) to insert
+or delete text in an hidden portion.
In the examples below, we show the @emph{display appearance} of the
buffer @code{foo}, which changes with the value of
@defvar selective-display-ellipses
If this buffer-local variable is non-@code{nil}, then Emacs displays
-@samp{@dots{}} at the end of a line that is followed by invisible text.
+@samp{@dots{}} at the end of a line that is followed by hidden text.
This example is a continuation of the previous one.
@example
(@samp{@dots{}}). @xref{Display Tables}.
@end defvar
-@node Overlay Arrow
-@section The Overlay Arrow
-@cindex overlay arrow
-
- The @dfn{overlay arrow} is useful for directing the user's attention
-to a particular line in a buffer. For example, in the modes used for
-interface to debuggers, the overlay arrow indicates the line of code
-about to be executed.
-
-@defvar overlay-arrow-string
-This variable holds the string to display to call attention to a
-particular line, or @code{nil} if the arrow feature is not in use.
-@end defvar
-
-@defvar overlay-arrow-position
-This variable holds a marker that indicates where to display the overlay
-arrow. It should point at the beginning of a line. The arrow text
-appears at the beginning of that line, overlaying any text that would
-otherwise appear. Since the arrow is usually short, and the line
-usually begins with indentation, normally nothing significant is
-overwritten.
-
-The overlay string is displayed only in the buffer that this marker
-points into. Thus, only one buffer can have an overlay arrow at any
-given time.
-@c !!! overlay-arrow-position: but the overlay string may remain in the display
-@c of some other buffer until an update is required. This should be fixed
-@c now. Is it?
-@end defvar
-
- You can do the same job by creating an overlay with a
-@code{before-string} property. @xref{Overlay Properties}.
-
@node Temporary Displays
@section Temporary Displays
- Temporary displays are used by commands to put output into a buffer
-and then present it to the user for perusal rather than for editing.
-Many of the help commands use this feature.
+ Temporary displays are used by Lisp programs to put output into a
+buffer and then present it to the user for perusal rather than for
+editing. Many help commands use this feature.
@defspec with-output-to-temp-buffer buffer-name forms@dots{}
-This function executes @var{forms} while arranging to insert any
-output they print into the buffer named @var{buffer-name}. The buffer
-is then shown in some window for viewing, displayed but not selected.
+This function executes @var{forms} while arranging to insert any output
+they print into the buffer named @var{buffer-name}, which is first
+created if necessary, and put into Help mode. Finally, the buffer is
+displayed in some window, but not selected.
+
+If the @var{forms} do not change the major mode in the output buffer,
+so that it is still Help mode at the end of their execution, then
+@code{with-output-to-temp-buffer} makes this buffer read-only at the
+end, and also scans it for function and variable names to make them
+into clickable cross-references. @xref{Docstring hyperlinks, , Tips
+for Documentation Strings}, in particular the item on hyperlinks in
+documentation strings, for more details.
The string @var{buffer-name} specifies the temporary buffer, which
need not already exist. The argument must be a string, not a buffer.
they are ``output'' in the general sense of the word, are not affected).
@xref{Output Functions}.
+Several hooks are available for customizing the behavior
+of this construct; they are listed below.
+
The value of the last form in @var{forms} is returned.
@example
calls it as a function to do the job of displaying a help buffer. The
function gets one argument, which is the buffer it should display.
-In Emacs versions 18 and earlier, this variable was called
-@code{temp-buffer-show-hook}.
+It is a good idea for this function to run @code{temp-buffer-show-hook}
+just as @code{with-output-to-temp-buffer} normally would, inside of
+@code{save-selected-window} and with the chosen window and buffer
+selected.
+@end defvar
+
+@defvar temp-buffer-setup-hook
+@tindex temp-buffer-setup-hook
+This normal hook is run by @code{with-output-to-temp-buffer} before
+evaluating @var{body}. When the hook runs, the temporary buffer is
+current. This hook is normally set up with a function to put the
+buffer in Help mode.
+@end defvar
+
+@defvar temp-buffer-show-hook
+This normal hook is run by @code{with-output-to-temp-buffer} after
+displaying the temporary buffer. When the hook runs, the temporary buffer
+is current, and the window it was displayed in is selected. This hook
+is normally set up with a function to make the buffer read only, and
+find function names and variable names in it, provided the major mode
+is Help mode.
@end defvar
@defun momentary-string-display string position &optional char message
The return value of @code{momentary-string-display} is not meaningful.
If the string @var{string} does not contain control characters, you can
-do the same job in a more general way by creating an overlay with a
-@code{before-string} property. @xref{Overlay Properties}.
+do the same job in a more general way by creating (and then subsequently
+deleting) an overlay with a @code{before-string} property.
+@xref{Overlay Properties}.
If @var{message} is non-@code{nil}, it is displayed in the echo area
while @var{string} is displayed in the buffer. If it is @code{nil}, a
beginning and end. It also has properties that you can examine and set;
these affect the display of the text within the overlay.
+An overlays uses markers to record its beginning and end; thus,
+editing the text of the buffer adjusts the beginning and end of each
+overlay so that it stays with the text. When you create the overlay,
+you can specify whether text inserted at the beginning should be
+inside the overlay or outside, and likewise for the end of the overlay.
+
@menu
-* Overlay Properties:: How to read and set properties.
+* Managing Overlays:: Creating and moving overlays.
+* Overlay Properties:: How to read and set properties.
What properties do to the screen display.
-* Managing Overlays:: Creating, moving, finding overlays.
+* Finding Overlays:: Searching for overlays.
@end menu
+@node Managing Overlays
+@subsection Managing Overlays
+
+ This section describes the functions to create, delete and move
+overlays, and to examine their contents. Overlay changes are not
+recorded in the buffer's undo list, since the overlays are not
+part of the buffer's contents.
+
+@defun overlayp object
+This function returns @code{t} if @var{object} is an overlay.
+@end defun
+
+@defun make-overlay start end &optional buffer front-advance rear-advance
+This function creates and returns an overlay that belongs to
+@var{buffer} and ranges from @var{start} to @var{end}. Both @var{start}
+and @var{end} must specify buffer positions; they may be integers or
+markers. If @var{buffer} is omitted, the overlay is created in the
+current buffer.
+
+The arguments @var{front-advance} and @var{rear-advance} specify the
+marker insertion type for the start of the overlay and for the end of
+the overlay, respectively. @xref{Marker Insertion Types}. If they
+are both @code{nil}, the default, then the overlay extends to include
+any text inserted at the beginning, but not text inserted at the end.
+If @var{front-advance} is non-@code{nil}, text inserted at the
+beginning of the overlay is excluded from the overlay. If
+@var{rear-advance} is non-@code{nil}, text inserted at the end of the
+overlay is included in the overlay.
+@end defun
+
+@defun overlay-start overlay
+This function returns the position at which @var{overlay} starts,
+as an integer.
+@end defun
+
+@defun overlay-end overlay
+This function returns the position at which @var{overlay} ends,
+as an integer.
+@end defun
+
+@defun overlay-buffer overlay
+This function returns the buffer that @var{overlay} belongs to. It
+returns @code{nil} if @var{overlay} has been deleted.
+@end defun
+
+@defun delete-overlay overlay
+This function deletes @var{overlay}. The overlay continues to exist as
+a Lisp object, and its property list is unchanged, but it ceases to be
+attached to the buffer it belonged to, and ceases to have any effect on
+display.
+
+A deleted overlay is not permanently disconnected. You can give it a
+position in a buffer again by calling @code{move-overlay}.
+@end defun
+
+@defun move-overlay overlay start end &optional buffer
+This function moves @var{overlay} to @var{buffer}, and places its bounds
+at @var{start} and @var{end}. Both arguments @var{start} and @var{end}
+must specify buffer positions; they may be integers or markers.
+
+If @var{buffer} is omitted, @var{overlay} stays in the same buffer it
+was already associated with; if @var{overlay} was deleted, it goes into
+the current buffer.
+
+The return value is @var{overlay}.
+
+This is the only valid way to change the endpoints of an overlay. Do
+not try modifying the markers in the overlay by hand, as that fails to
+update other vital data structures and can cause some overlays to be
+``lost''.
+@end defun
+
+@defun remove-overlays &optional start end name value
+This function removes all the overlays between @var{start} and
+@var{end} whose property @var{name} has the value @var{value}. It can
+move the endpoints of the overlays in the region, or split them.
+
+If @var{name} is omitted or @code{nil}, it means to delete all overlays in
+the specified region. If @var{start} and/or @var{end} are omitted or
+@code{nil}, that means the beginning and end of the buffer respectively.
+Therefore, @code{(remove-overlays)} removes all the overlays in the
+current buffer.
+@end defun
+
+ Here are some examples:
+
+@example
+;; @r{Create an overlay.}
+(setq foo (make-overlay 1 10))
+ @result{} #<overlay from 1 to 10 in display.texi>
+(overlay-start foo)
+ @result{} 1
+(overlay-end foo)
+ @result{} 10
+(overlay-buffer foo)
+ @result{} #<buffer display.texi>
+;; @r{Give it a property we can check later.}
+(overlay-put foo 'happy t)
+ @result{} t
+;; @r{Verify the property is present.}
+(overlay-get foo 'happy)
+ @result{} t
+;; @r{Move the overlay.}
+(move-overlay foo 5 20)
+ @result{} #<overlay from 5 to 20 in display.texi>
+(overlay-start foo)
+ @result{} 5
+(overlay-end foo)
+ @result{} 20
+;; @r{Delete the overlay.}
+(delete-overlay foo)
+ @result{} nil
+;; @r{Verify it is deleted.}
+foo
+ @result{} #<overlay in no buffer>
+;; @r{A deleted overlay has no position.}
+(overlay-start foo)
+ @result{} nil
+(overlay-end foo)
+ @result{} nil
+(overlay-buffer foo)
+ @result{} nil
+;; @r{Undelete the overlay.}
+(move-overlay foo 1 20)
+ @result{} #<overlay from 1 to 20 in display.texi>
+;; @r{Verify the results.}
+(overlay-start foo)
+ @result{} 1
+(overlay-end foo)
+ @result{} 20
+(overlay-buffer foo)
+ @result{} #<buffer display.texi>
+;; @r{Moving and deleting the overlay does not change its properties.}
+(overlay-get foo 'happy)
+ @result{} t
+@end example
+
@node Overlay Properties
@subsection Overlay Properties
-Overlay properties are like text properties in some respects, but the
-differences are more important than the similarities. Text properties
-are considered a part of the text; overlays are specifically considered
-not to be part of the text. Thus, copying text between various buffers
-and strings preserves text properties, but does not try to preserve
-overlays. Changing a buffer's text properties marks the buffer as
-modified, while moving an overlay or changing its properties does not.
-Unlike text propery changes, overlay changes are not recorded in the
-buffer's undo list.
+ Overlay properties are like text properties in that the properties that
+alter how a character is displayed can come from either source. But in
+most respects they are different. @xref{Text Properties}, for comparison.
+
+ Text properties are considered a part of the text; overlays and
+their properties are specifically considered not to be part of the
+text. Thus, copying text between various buffers and strings
+preserves text properties, but does not try to preserve overlays.
+Changing a buffer's text properties marks the buffer as modified,
+while moving an overlay or changing its properties does not. Unlike
+text property changes, overlay property changes are not recorded in
+the buffer's undo list.
+
+ These functions read and set the properties of an overlay:
+
+@defun overlay-get overlay prop
+This function returns the value of property @var{prop} recorded in
+@var{overlay}, if any. If @var{overlay} does not record any value for
+that property, but it does have a @code{category} property which is a
+symbol, that symbol's @var{prop} property is used. Otherwise, the value
+is @code{nil}.
+@end defun
+
+@defun overlay-put overlay prop value
+This function sets the value of property @var{prop} recorded in
+@var{overlay} to @var{value}. It returns @var{value}.
+@end defun
+
+@defun overlay-properties overlay
+This returns a copy of the property list of @var{overlay}.
+@end defun
+
+ See also the function @code{get-char-property} which checks both
+overlay properties and text properties for a given character.
+@xref{Examining Properties}.
+
+ Many overlay properties have special meanings; here is a table
+of them:
@table @code
@item priority
@kindex priority @r{(overlay property)}
-This property's value (which should be a nonnegative number) determines
-the priority of the overlay. The priority matters when two or more
-overlays cover the same character and both specify a face for display;
-the one whose @code{priority} value is larger takes priority over the
-other, and its face attributes override the face attributes of the lower
-priority overlay.
+This property's value (which should be a nonnegative integer number)
+determines the priority of the overlay. The priority matters when two
+or more overlays cover the same character and both specify the same
+property; the one whose @code{priority} value is larger takes priority
+over the other. For the @code{face} property, the higher priority
+value does not completely replace the other; instead, its face
+attributes override the face attributes of the lower priority
+@code{face} property.
Currently, all overlays take priority over text properties. Please
avoid using negative priority values, as we have not yet decided just
@item face
@kindex face @r{(overlay property)}
This property controls the way text is displayed---for example, which
-font and which colors. Its value is a face name or a list of face
-names. @xref{Faces}, for more information.
+font and which colors. @xref{Faces}, for more information.
-If the property value is a list, elements may also have the form
-@code{(foreground-color . @var{color-name})} or @code{(background-color
-. @var{color-name})}. These elements specify just the foreground color
-or just the background color; therefore, there is no need to create a
-face for each color that you want to use.
+In the simplest case, the value is a face name. It can also be a list;
+then each element can be any of these possibilities:
-@item mouse-face
-@kindex mouse-face @r{(overlay property)}
-This property is used instead of @code{face} when the mouse is within
-the range of the overlay.
+@itemize @bullet
+@item
+A face name (a symbol or string).
-@item modification-hooks
+@item
+A property list of face attributes. This has the form (@var{keyword}
+@var{value} @dots{}), where each @var{keyword} is a face attribute
+name and @var{value} is a meaningful value for that attribute. With
+this feature, you do not need to create a face each time you want to
+specify a particular attribute for certain text. @xref{Face
+Attributes}.
+
+@item
+A cons cell of the form @code{(foreground-color . @var{color-name})} or
+@code{(background-color . @var{color-name})}. These elements specify
+just the foreground color or just the background color.
+
+@code{(foreground-color . @var{color-name})} has the same effect as
+@code{(:foreground @var{color-name})}; likewise for the background.
+@end itemize
+
+@item mouse-face
+@kindex mouse-face @r{(overlay property)}
+This property is used instead of @code{face} when the mouse is within
+the range of the overlay.
+
+@item display
+@kindex display @r{(overlay property)}
+This property activates various features that change the
+way text is displayed. For example, it can make text appear taller
+or shorter, higher or lower, wider or narrower, or replaced with an image.
+@xref{Display Property}.
+
+@item help-echo
+@kindex help-echo @r{(overlay property)}
+If an overlay has a @code{help-echo} property, then when you move the
+mouse onto the text in the overlay, Emacs displays a help string in the
+echo area, or in the tooltip window. For details see @ref{Text
+help-echo}.
+
+@item modification-hooks
@kindex modification-hooks @r{(overlay property)}
This property's value is a list of functions to be called if any
character within the overlay is changed or if text is inserted strictly
length is the number of characters deleted, and the post-change
beginning and end are equal.)
+If these functions modify the buffer, they should bind
+@code{inhibit-modification-hooks} to @code{t} around doing so, to
+avoid confusing the internal mechanism that calls these hooks.
+
@item insert-in-front-hooks
@kindex insert-in-front-hooks @r{(overlay property)}
This property's value is a list of functions to be called before and
@code{intangible} text property. @xref{Special Properties}, for details.
@item isearch-open-invisible
-@itemx isearch-open-invisible-temporary
-These properties control how incremental search should make invisible an
-overlay visible, either permanently or temporarily. @xref{Invisible
+This property tells incremental search how to make an invisible overlay
+visible, permanently, if the final match overlaps it. @xref{Invisible
Text}.
+@item isearch-open-invisible-temporary
+This property tells incremental search how to make an invisible overlay
+visible, temporarily, during the search. @xref{Invisible Text}.
+
@item before-string
@kindex before-string @r{(overlay property)}
This property's value is a string to add to the display at the beginning
of the overlay. The string does not appear in the buffer in any
-sense---only on the screen. The string should contain only characters
-that display as a single column---control characters, including tabs or
-newlines, will give strange results.
+sense---only on the screen.
@item after-string
@kindex after-string @r{(overlay property)}
This property's value is a string to add to the display at the end of
the overlay. The string does not appear in the buffer in any
-sense---only on the screen. The string should contain only characters
-that display as a single column---control characters, including tabs or
-newlines, will give strange results.
+sense---only on the screen.
@item evaporate
@kindex evaporate @r{(overlay property)}
If this property is non-@code{nil}, the overlay is deleted automatically
-if it ever becomes empty (i.e., if it spans no characters).
+if it becomes empty (i.e., if its length becomes zero). If you give
+an empty overlay a non-@code{nil} @code{evaporate} property, that deletes
+it immediately.
@item local-map
-@cindex keymap of character
-@kindex local-map @r{(text property)}
+@cindex keymap of character (and overlays)
+@kindex local-map @r{(overlay property)}
If this property is non-@code{nil}, it specifies a keymap for a portion
of the text. The property's value replaces the buffer's local map, when
the character after point is within the overlay. @xref{Active Keymaps}.
-@end table
-
- These are the functions for reading and writing the properties of an
-overlay.
-
-@defun overlay-get overlay prop
-This function returns the value of property @var{prop} recorded in
-@var{overlay}, if any. If @var{overlay} does not record any value for
-that property, but it does have a @code{category} property which is a
-symbol, that symbol's @var{prop} property is used. Otherwise, the value
-is @code{nil}.
-@end defun
-
-@defun overlay-put overlay prop value
-This function sets the value of property @var{prop} recorded in
-@var{overlay} to @var{value}. It returns @var{value}.
-@end defun
-
- See also the function @code{get-char-property} which checks both
-overlay properties and text properties for a given character.
-@xref{Examining Properties}.
-
-@node Managing Overlays
-@subsection Managing Overlays
-
- This section describes the functions to create, delete and move
-overlays, and to examine their contents.
-
-@defun make-overlay start end &optional buffer front-advance rear-advance
-This function creates and returns an overlay that belongs to
-@var{buffer} and ranges from @var{start} to @var{end}. Both @var{start}
-and @var{end} must specify buffer positions; they may be integers or
-markers. If @var{buffer} is omitted, the overlay is created in the
-current buffer.
-
-The arguments @var{front-advance} and @var{rear-advance} specify the
-insertion type for the start of the overlay and for the end of the
-overlay. @xref{Marker Insertion Types}.
-@end defun
-
-@defun overlay-start overlay
-This function returns the position at which @var{overlay} starts,
-as an integer.
-@end defun
-
-@defun overlay-end overlay
-This function returns the position at which @var{overlay} ends,
-as an integer.
-@end defun
-@defun overlay-buffer overlay
-This function returns the buffer that @var{overlay} belongs to.
-@end defun
-
-@defun delete-overlay overlay
-This function deletes @var{overlay}. The overlay continues to exist as
-a Lisp object, but ceases to be part of the buffer it belonged to, and
-ceases to have any effect on display.
-@end defun
+@item keymap
+@kindex keymap @r{(overlay property)}
+The @code{keymap} property is similar to @code{local-map} but overrides the
+buffer's local map (and the map specified by the @code{local-map}
+property) rather than replacing it.
+@end table
-@defun move-overlay overlay start end &optional buffer
-This function moves @var{overlay} to @var{buffer}, and places its bounds
-at @var{start} and @var{end}. Both arguments @var{start} and @var{end}
-must specify buffer positions; they may be integers or markers. If
-@var{buffer} is omitted, the overlay stays in the same buffer.
+@node Finding Overlays
+@subsection Searching for Overlays
-The return value is @var{overlay}.
+@defun overlays-at pos
+This function returns a list of all the overlays that cover the
+character at position @var{pos} in the current buffer. The list is in
+no particular order. An overlay contains position @var{pos} if it
+begins at or before @var{pos}, and ends after @var{pos}.
-This is the only valid way to change the endpoints of an overlay. Do
-not try modifying the markers in the overlay by hand, as that fails to
-update other vital data structures and can cause some overlays to be
-``lost''.
-@end defun
+To illustrate usage, here is a Lisp function that returns a list of the
+overlays that specify property @var{prop} for the character at point:
-@defun overlays-at pos
-This function returns a list of all the overlays that contain position
-@var{pos} in the current buffer. The list is in no particular order.
-An overlay contains position @var{pos} if it begins at or before
-@var{pos}, and ends after @var{pos}.
+@smallexample
+(defun find-overlays-specifying (prop)
+ (let ((overlays (overlays-at (point)))
+ found)
+ (while overlays
+ (let ((overlay (car overlays)))
+ (if (overlay-get overlay prop)
+ (setq found (cons overlay found))))
+ (setq overlays (cdr overlays)))
+ found))
+@end smallexample
@end defun
-@tindex overlays-in
@defun overlays-in beg end
This function returns a list of the overlays that overlap the region
@var{beg} through @var{end}. ``Overlap'' means that at least one
character is contained within the overlay and also contained within the
specified region; however, empty overlays are included in the result if
-they are located at @var{beg} or between @var{beg} and @var{end}.
+they are located at @var{beg}, or strictly between @var{beg} and @var{end}.
@end defun
@defun next-overlay-change pos
This function returns the buffer position of the next beginning or end
-of an overlay, after @var{pos}.
+of an overlay, after @var{pos}. If there is none, it returns
+@code{(point-max)}.
@end defun
@defun previous-overlay-change pos
This function returns the buffer position of the previous beginning or
-end of an overlay, before @var{pos}.
+end of an overlay, before @var{pos}. If there is none, it returns
+@code{(point-min)}.
@end defun
+ Here's an easy way to use @code{next-overlay-change} to search for the
+next character which gets a non-@code{nil} @code{happy} property from
+either its overlays or its text properties (@pxref{Property Search}):
+
+@smallexample
+(defun find-overlay-prop (prop)
+ (save-excursion
+ (while (and (not (eobp))
+ (not (get-char-property (point) 'happy)))
+ (goto-char (min (next-overlay-change (point))
+ (next-single-property-change (point) 'happy))))
+ (point)))
+@end smallexample
+
@node Width
@section Width
Since not all characters have the same width, these functions let you
-check the width of a character. @ref{Primitive Indent}
+check the width of a character. @xref{Primitive Indent}, and
+@ref{Screen Lines}, for related functions.
-@xref{Screen Lines}, for related
-functions.
-
-@tindex char-width
@defun char-width char
This function returns the width in columns of the character @var{char},
if it were displayed in the current buffer and the selected window.
@end defun
-@tindex string-width
@defun string-width string
This function returns the width in columns of the string @var{string},
if it were displayed in the current buffer and the selected window.
@end defun
-@tindex truncate-string-to-width
-@defun truncate-string-to-width string width &optional start-column padding
-This function returns the part of @var{string} that fits within
-@var{width} columns, as a new string.
+@defun truncate-string-to-width string width &optional start-column padding ellipsis
+This function returns the part of @var{string} that fits within
+@var{width} columns, as a new string.
+
+If @var{string} does not reach @var{width}, then the result ends where
+@var{string} ends. If one multi-column character in @var{string}
+extends across the column @var{width}, that character is not included in
+the result. Thus, the result can fall short of @var{width} but cannot
+go beyond it.
+
+The optional argument @var{start-column} specifies the starting column.
+If this is non-@code{nil}, then the first @var{start-column} columns of
+the string are omitted from the value. If one multi-column character in
+@var{string} extends across the column @var{start-column}, that
+character is not included.
+
+The optional argument @var{padding}, if non-@code{nil}, is a padding
+character added at the beginning and end of the result string, to extend
+it to exactly @var{width} columns. The padding character is used at the
+end of the result if it falls short of @var{width}. It is also used at
+the beginning of the result if one multi-column character in
+@var{string} extends across the column @var{start-column}.
+
+If @var{ellipsis} is non-@code{nil}, it should be a string which will
+replace the end of @var{str} (including any padding) if it extends
+beyond @var{end-column}, unless the display width of @var{str} is
+equal to or less than the display width of @var{ellipsis}. If
+@var{ellipsis} is non-@code{nil} and not a string, it stands for
+@code{"..."}.
+
+@example
+(truncate-string-to-width "\tab\t" 12 4)
+ @result{} "ab"
+(truncate-string-to-width "\tab\t" 12 4 ?\s)
+ @result{} " ab "
+@end example
+@end defun
+
+@node Line Height
+@section Line Height
+@cindex line height
+
+ The total height of each display line consists of the height of the
+contents of the line, and additional vertical line spacing below the
+display row.
+
+ The height of the line contents is normally determined from the
+maximum height of any character or image on that display line,
+including the final newline if there is one. (A line that is
+continued doesn't include a final newline.) In the most common case,
+the line height equals the height of the default frame font.
+
+ There are several ways to explicitly control or change the line
+height, either by specifying an absolute height for the display line,
+or by adding additional vertical space below one or all lines.
+
+@kindex line-height @r{(text property)}
+ A newline can have a @code{line-height} text or overlay property
+that controls the total height of the display line ending in that
+newline.
+
+ If the property value is a list @code{(@var{height} @var{total})},
+then @var{height} is used as the actual property value for the
+@code{line-height}, and @var{total} specifies the total displayed
+height of the line, so the line spacing added below the line equals
+the @var{total} height minus the actual line height. In this case,
+the other ways to specify the line spacing are ignored.
+
+ If the property value is @code{t}, the displayed height of the
+line is exactly what its contents demand; no line-spacing is added.
+This case is useful for tiling small images or image slices without
+adding blank areas between the images.
+
+ If the property value is not @code{t}, it is a height spec. A height
+spec stands for a numeric height value; this height spec specifies the
+actual line height, @var{line-height}. There are several ways to
+write a height spec; here's how each of them translates into a numeric
+height:
+
+@table @code
+@item @var{integer}
+If the height spec is a positive integer, the height value is that integer.
+@item @var{float}
+If the height spec is a float, @var{float}, the numeric height value
+is @var{float} times the frame's default line height.
+@item (@var{face} . @var{ratio})
+If the height spec is a cons of the format shown, the numeric height
+is @var{ratio} times the height of face @var{face}. @var{ratio} can
+be any type of number, or @code{nil} which means a ratio of 1.
+If @var{face} is @code{t}, it refers to the current face.
+@item (nil . @var{ratio})
+If the height spec is a cons of the format shown, the numeric height
+is @var{ratio} times the height of the contents of the line.
+@end table
+
+ Thus, any valid non-@code{t} property value specifies a height in pixels,
+@var{line-height}, one way or another. If the line contents' height
+is less than @var{line-height}, Emacs adds extra vertical space above
+the line to achieve the total height @var{line-height}. Otherwise,
+@var{line-height} has no effect.
+
+ If you don't specify the @code{line-height} property, the line's
+height consists of the contents' height plus the line spacing.
+There are several ways to specify the line spacing for different
+parts of Emacs text.
+
+@vindex default-line-spacing
+ You can specify the line spacing for all lines in a frame with the
+@code{line-spacing} frame parameter, @xref{Window Frame Parameters}.
+However, if the variable @code{default-line-spacing} is
+non-@code{nil}, it overrides the frame's @code{line-spacing}
+parameter. An integer value specifies the number of pixels put below
+lines on window systems. A floating point number specifies the
+spacing relative to the frame's default line height.
+
+@vindex line-spacing
+ You can specify the line spacing for all lines in a buffer via the
+buffer-local @code{line-spacing} variable. An integer value specifies
+the number of pixels put below lines on window systems. A floating
+point number specifies the spacing relative to the default frame line
+height. This overrides line spacings specified for the frame.
+
+@kindex line-spacing @r{(text property)}
+ Finally, a newline can have a @code{line-spacing} text or overlay
+property that controls the height of the display line ending with that
+newline. The property value overrides the default frame line spacing
+and the buffer local @code{line-spacing} variable.
+
+ One way or another, these mechanisms specify a Lisp value for the
+spacing of each line. The value is a height spec, and it translates
+into a Lisp value as described above. However, in this case the
+numeric height value specifies the line spacing, rather than the line
+height.
+
+@node Faces
+@section Faces
+@cindex faces
+
+ A @dfn{face} is a named collection of graphical attributes: font
+family, foreground color, background color, optional underlining, and
+many others. Faces are used in Emacs to control the style of display of
+particular parts of the text or the frame.
+
+@cindex face id
+Each face has its own @dfn{face number}, which distinguishes faces at
+low levels within Emacs. However, for most purposes, you refer to
+faces in Lisp programs by the symbols that name them.
+
+@defun facep object
+This function returns @code{t} if @var{object} is a face name string
+or symbol (or if it is a vector of the kind used internally to record
+face data). It returns @code{nil} otherwise.
+@end defun
+
+Each face name is meaningful for all frames, and by default it has the
+same meaning in all frames. But you can arrange to give a particular
+face name a special meaning in one frame if you wish.
+
+@menu
+* Standard Faces:: The faces Emacs normally comes with.
+* Defining Faces:: How to define a face with @code{defface}.
+* Face Attributes:: What is in a face?
+* Attribute Functions:: Functions to examine and set face attributes.
+* Displaying Faces:: How Emacs combines the faces specified for a character.
+* Font Selection:: Finding the best available font for a face.
+* Face Functions:: How to define and examine faces.
+* Auto Faces:: Hook for automatic face assignment.
+* Font Lookup:: Looking up the names of available fonts
+ and information about them.
+* Fontsets:: A fontset is a collection of fonts
+ that handle a range of character sets.
+@end menu
+
+@node Standard Faces
+@subsection Standard Faces
+
+ This table lists all the standard faces and their uses. Most of them
+are used for displaying certain parts of the frames or certain kinds of
+text; you can control how those places look by customizing these faces.
+
+@table @code
+@item default
+@kindex default @r{(face name)}
+This face is used for ordinary text.
+
+@item mode-line
+@kindex mode-line @r{(face name)}
+This face is used for the mode line of the selected window, and for
+menu bars when toolkit menus are not used.
+
+@item modeline
+@kindex modeline @r{(face name)}
+This is an alias for the @code{mode-line} face, for compatibility with
+old Emacs versions.
+
+@item mode-line-inactive
+@kindex mode-line-inactive @r{(face name)}
+This face is used for mode lines of non-selected windows.
+This face inherits from @code{mode-line}, so changes
+in that face affect all windows.
+
+@item header-line
+@kindex header-line @r{(face name)}
+This face is used for the header lines of windows that have them.
+
+@item menu
+This face controls the display of menus, both their colors and their
+font. (This works only on certain systems.)
+
+@item fringe
+@kindex fringe @r{(face name)}
+This face controls the default colors of window fringes, the thin
+areas on either side that are used to display continuation and
+truncation glyphs. Other faces used to display bitmaps in the fringe
+are implicitly merged with this face.
+
+@item minibuffer-prompt
+@kindex minibuffer-prompt @r{(face name)}
+@vindex minibuffer-prompt-properties
+This face is used for the text of minibuffer prompts. By default,
+Emacs automatically adds this face to the value of
+@code{minibuffer-prompt-properties}, which is a list of text
+properties used to display the prompt text.
+
+@item scroll-bar
+@kindex scroll-bar @r{(face name)}
+This face controls the colors for display of scroll bars.
+
+@item tool-bar
+@kindex tool-bar @r{(face name)}
+This face is used for display of the tool bar, if any.
+
+@item region
+@kindex region @r{(face name)}
+This face is used for highlighting the region in Transient Mark mode.
+
+@item secondary-selection
+@kindex secondary-selection @r{(face name)}
+This face is used to show any secondary selection you have made.
+
+@item highlight
+@kindex highlight @r{(face name)}
+This face is meant to be used for highlighting for various purposes.
+
+@item mode-line-highlight
+@kindex mode-line-highlight @r{(face name)}
+This face is used for highlighting something on @code{mode-line} or
+@code{header-line} for various purposes.
+
+@item trailing-whitespace
+@kindex trailing-whitespace @r{(face name)}
+This face is used to display excess whitespace at the end of a line,
+if @code{show-trailing-whitespace} is non-@code{nil}.
+
+@item escape-glyph
+@kindex escape-glyph @r{(face name)}
+This face is used to display control characters and escape glyphs.
+@end table
+
+ In contrast, these faces are provided to change the appearance of text
+in specific ways. You can use them on specific text, when you want
+the effects they produce.
+
+@table @code
+@item bold
+@kindex bold @r{(face name)}
+This face uses a bold font, if possible. It uses the bold variant of
+the frame's font, if it has one. It's up to you to choose a default
+font that has a bold variant, if you want to use one.
+
+@item italic
+@kindex italic @r{(face name)}
+This face uses the italic variant of the frame's font, if it has one.
+
+@item bold-italic
+@kindex bold-italic @r{(face name)}
+This face uses the bold italic variant of the frame's font, if it has
+one.
+
+@item underline
+@kindex underline @r{(face name)}
+This face underlines text.
+
+@item fixed-pitch
+@kindex fixed-pitch @r{(face name)}
+This face forces use of a particular fixed-width font.
+
+@item variable-pitch
+@kindex variable-pitch @r{(face name)}
+This face forces use of a particular variable-width font. It's
+reasonable to customize this to use a different variable-width font, if
+you like, but you should not make it a fixed-width font.
+
+@item shadow
+@kindex shadow @r{(face name)}
+This face is used for making the text less noticeable than the
+surrounding ordinary text.
+@end table
+
+@defvar show-trailing-whitespace
+@tindex show-trailing-whitespace
+If this variable is non-@code{nil}, Emacs uses the
+@code{trailing-whitespace} face to display any spaces and tabs at the
+end of a line.
+@end defvar
+
+@node Defining Faces
+@subsection Defining Faces
+
+ The way to define a new face is with @code{defface}. This creates a
+kind of customization item (@pxref{Customization}) which the user can
+customize using the Customization buffer (@pxref{Easy Customization,,,
+emacs, The GNU Emacs Manual}).
+
+@defmac defface face spec doc [keyword value]...
+This declares @var{face} as a customizable face that defaults
+according to @var{spec}. You should not quote the symbol @var{face},
+and it should not end in @samp{-face} (that would be redundant). The
+argument @var{doc} specifies the face documentation. The keywords you
+can use in @code{defface} are the same as in @code{defgroup} and
+@code{defcustom} (@pxref{Common Keywords}).
+
+When @code{defface} executes, it defines the face according to
+@var{spec}, then uses any customizations that were read from the
+init file (@pxref{Init File}) to override that specification.
+
+The purpose of @var{spec} is to specify how the face should appear on
+different kinds of terminals. It should be an alist whose elements
+have the form @code{(@var{display} @var{atts})}. Each element's
+@sc{car}, @var{display}, specifies a class of terminals. (The first
+element, if it s @sc{car} is @code{default}, is special---it specifies
+defaults for the remaining elements). The element's @sc{cadr},
+@var{atts}, is a list of face attributes and their values; it
+specifies what the face should look like on that kind of terminal.
+The possible attributes are defined in the value of
+@code{custom-face-attributes}.
+
+The @var{display} part of an element of @var{spec} determines which
+frames the element matches. If more than one element of @var{spec}
+matches a given frame, the first element that matches is the one used
+for that frame. There are three possibilities for @var{display}:
+
+@table @asis
+@item @code{default}
+This element of @var{spec} doesn't match any frames; instead, it
+specifies defaults that apply to all frames. This kind of element, if
+used, must be the first element of @var{spec}. Each of the following
+elements can override any or all of these defaults.
+
+@item @code{t}
+This element of @var{spec} matches all frames. Therefore, any
+subsequent elements of @var{spec} are never used. Normally
+@code{t} is used in the last (or only) element of @var{spec}.
+
+@item a list
+If @var{display} is a list, each element should have the form
+@code{(@var{characteristic} @var{value}@dots{})}. Here
+@var{characteristic} specifies a way of classifying frames, and the
+@var{value}s are possible classifications which @var{display} should
+apply to. Here are the possible values of @var{characteristic}:
+
+@table @code
+@item type
+The kind of window system the frame uses---either @code{graphic} (any
+graphics-capable display), @code{x}, @code{pc} (for the MS-DOS console),
+@code{w32} (for MS Windows 9X/NT), or @code{tty} (a non-graphics-capable
+display).
+
+@item class
+What kinds of colors the frame supports---either @code{color},
+@code{grayscale}, or @code{mono}.
+
+@item background
+The kind of background---either @code{light} or @code{dark}.
+
+@item min-colors
+An integer that represents the minimum number of colors the frame
+should support. This matches a frame if its
+@code{display-color-cells} value is at least the specified integer.
+
+@item supports
+Whether or not the frame can display the face attributes given in
+@var{value}@dots{} (@pxref{Face Attributes}). See the documentation
+for the function @code{display-supports-face-attributes-p} for more
+information on exactly how this testing is done. @xref{Display Face
+Attribute Testing}.
+@end table
+
+If an element of @var{display} specifies more than one @var{value} for a
+given @var{characteristic}, any of those values is acceptable. If
+@var{display} has more than one element, each element should specify a
+different @var{characteristic}; then @emph{each} characteristic of the
+frame must match one of the @var{value}s specified for it in
+@var{display}.
+@end table
+@end defmac
+
+ Here's how the standard face @code{region} is defined:
+
+@example
+@group
+ '((((class color) (min-colors 88) (background dark))
+ :background "blue3")
+@end group
+ (((class color) (min-colors 88) (background light))
+ :background "lightgoldenrod2")
+ (((class color) (min-colors 16) (background dark))
+ :background "blue3")
+ (((class color) (min-colors 16) (background light))
+ :background "lightgoldenrod2")
+ (((class color) (min-colors 8))
+ :background "blue" :foreground "white")
+ (((type tty) (class mono))
+ :inverse-video t)
+ (t :background "gray"))
+@group
+ "Basic face for highlighting the region."
+ :group 'basic-faces)
+@end group
+@end example
+
+ Internally, @code{defface} uses the symbol property
+@code{face-defface-spec} to record the face attributes specified in
+@code{defface}, @code{saved-face} for the attributes saved by the user
+with the customization buffer, @code{customized-face} for the
+attributes customized by the user for the current session, but not
+saved, and @code{face-documentation} for the documentation string.
+
+@defopt frame-background-mode
+This option, if non-@code{nil}, specifies the background type to use for
+interpreting face definitions. If it is @code{dark}, then Emacs treats
+all frames as if they had a dark background, regardless of their actual
+background colors. If it is @code{light}, then Emacs treats all frames
+as if they had a light background.
+@end defopt
+
+@node Face Attributes
+@subsection Face Attributes
+@cindex face attributes
+
+ The effect of using a face is determined by a fixed set of @dfn{face
+attributes}. This table lists all the face attributes, and what they
+mean. Note that in general, more than one face can be specified for a
+given piece of text; when that happens, the attributes of all the faces
+are merged to specify how to display the text. @xref{Displaying Faces}.
+
+ Any attribute in a face can have the value @code{unspecified}. This
+means the face doesn't specify that attribute. In face merging, when
+the first face fails to specify a particular attribute, that means the
+next face gets a chance. However, the @code{default} face must
+specify all attributes.
+
+ Some of these font attributes are meaningful only on certain kinds of
+displays---if your display cannot handle a certain attribute, the
+attribute is ignored. (The attributes @code{:family}, @code{:width},
+@code{:height}, @code{:weight}, and @code{:slant} correspond to parts of
+an X Logical Font Descriptor.)
+
+@table @code
+@item :family
+Font family name, or fontset name (@pxref{Fontsets}). If you specify a
+font family name, the wild-card characters @samp{*} and @samp{?} are
+allowed.
+
+@item :width
+Relative proportionate width, also known as the character set width or
+set width. This should be one of the symbols @code{ultra-condensed},
+@code{extra-condensed}, @code{condensed}, @code{semi-condensed},
+@code{normal}, @code{semi-expanded}, @code{expanded},
+@code{extra-expanded}, or @code{ultra-expanded}.
+
+@item :height
+Either the font height, an integer in units of 1/10 point, a floating
+point number specifying the amount by which to scale the height of any
+underlying face, or a function, which is called with the old height
+(from the underlying face), and should return the new height.
+
+@item :weight
+Font weight---a symbol from this series (from most dense to most faint):
+@code{ultra-bold}, @code{extra-bold}, @code{bold}, @code{semi-bold},
+@code{normal}, @code{semi-light}, @code{light}, @code{extra-light},
+or @code{ultra-light}.
+
+On a text-only terminal, any weight greater than normal is displayed as
+extra bright, and any weight less than normal is displayed as
+half-bright (provided the terminal supports the feature).
+
+@item :slant
+Font slant---one of the symbols @code{italic}, @code{oblique}, @code{normal},
+@code{reverse-italic}, or @code{reverse-oblique}.
+
+On a text-only terminal, slanted text is displayed as half-bright, if
+the terminal supports the feature.
+
+@item :foreground
+Foreground color, a string. The value can be a system-defined color
+name, or a hexadecimal color specification of the form
+@samp{#@var{rr}@var{gg}@var{bb}}. (@samp{#000000} is black,
+@samp{#ff0000} is red, @samp{#00ff00} is green, @samp{#0000ff} is
+blue, and @samp{#ffffff} is white.)
+
+@item :background
+Background color, a string, like the foreground color.
+
+@item :inverse-video
+Whether or not characters should be displayed in inverse video. The
+value should be @code{t} (yes) or @code{nil} (no).
+
+@item :stipple
+The background stipple, a bitmap.
+
+The value can be a string; that should be the name of a file containing
+external-format X bitmap data. The file is found in the directories
+listed in the variable @code{x-bitmap-file-path}.
+
+Alternatively, the value can specify the bitmap directly, with a list
+of the form @code{(@var{width} @var{height} @var{data})}. Here,
+@var{width} and @var{height} specify the size in pixels, and
+@var{data} is a string containing the raw bits of the bitmap, row by
+row. Each row occupies @math{(@var{width} + 7) / 8} consecutive bytes
+in the string (which should be a unibyte string for best results).
+This means that each row always occupies at least one whole byte.
+
+If the value is @code{nil}, that means use no stipple pattern.
+
+Normally you do not need to set the stipple attribute, because it is
+used automatically to handle certain shades of gray.
+
+@item :underline
+Whether or not characters should be underlined, and in what color. If
+the value is @code{t}, underlining uses the foreground color of the
+face. If the value is a string, underlining uses that color. The
+value @code{nil} means do not underline.
+
+@item :overline
+Whether or not characters should be overlined, and in what color.
+The value is used like that of @code{:underline}.
+
+@item :strike-through
+Whether or not characters should be strike-through, and in what
+color. The value is used like that of @code{:underline}.
+
+@item :inherit
+The name of a face from which to inherit attributes, or a list of face
+names. Attributes from inherited faces are merged into the face like an
+underlying face would be, with higher priority than underlying faces.
+If a list of faces is used, attributes from faces earlier in the list
+override those from later faces.
+
+@item :box
+Whether or not a box should be drawn around characters, its color, the
+width of the box lines, and 3D appearance.
+@end table
+
+ Here are the possible values of the @code{:box} attribute, and what
+they mean:
+
+@table @asis
+@item @code{nil}
+Don't draw a box.
+
+@item @code{t}
+Draw a box with lines of width 1, in the foreground color.
+
+@item @var{color}
+Draw a box with lines of width 1, in color @var{color}.
+
+@item @code{(:line-width @var{width} :color @var{color} :style @var{style})}
+This way you can explicitly specify all aspects of the box. The value
+@var{width} specifies the width of the lines to draw; it defaults to 1.
+
+The value @var{color} specifies the color to draw with. The default is
+the foreground color of the face for simple boxes, and the background
+color of the face for 3D boxes.
+
+The value @var{style} specifies whether to draw a 3D box. If it is
+@code{released-button}, the box looks like a 3D button that is not being
+pressed. If it is @code{pressed-button}, the box looks like a 3D button
+that is being pressed. If it is @code{nil} or omitted, a plain 2D box
+is used.
+@end table
+
+ In older versions of Emacs, before @code{:family}, @code{:height},
+@code{:width}, @code{:weight}, and @code{:slant} existed, these
+attributes were used to specify the type face. They are now
+semi-obsolete, but they still work:
+
+@table @code
+@item :font
+This attribute specifies the font name.
+
+@item :bold
+A non-@code{nil} value specifies a bold font.
+
+@item :italic
+A non-@code{nil} value specifies an italic font.
+@end table
+
+ For compatibility, you can still set these ``attributes'', even
+though they are not real face attributes. Here is what that does:
+
+@table @code
+@item :font
+You can specify an X font name as the ``value'' of this ``attribute'';
+that sets the @code{:family}, @code{:width}, @code{:height},
+@code{:weight}, and @code{:slant} attributes according to the font name.
+
+If the value is a pattern with wildcards, the first font that matches
+the pattern is used to set these attributes.
+
+@item :bold
+A non-@code{nil} makes the face bold; @code{nil} makes it normal.
+This actually works by setting the @code{:weight} attribute.
+
+@item :italic
+A non-@code{nil} makes the face italic; @code{nil} makes it normal.
+This actually works by setting the @code{:slant} attribute.
+@end table
+
+@defvar x-bitmap-file-path
+This variable specifies a list of directories for searching
+for bitmap files, for the @code{:stipple} attribute.
+@end defvar
+
+@defun bitmap-spec-p object
+This returns @code{t} if @var{object} is a valid bitmap specification,
+suitable for use with @code{:stipple} (see above). It returns
+@code{nil} otherwise.
+@end defun
+
+@node Attribute Functions
+@subsection Face Attribute Functions
+
+ You can modify the attributes of an existing face with the following
+functions. If you specify @var{frame}, they affect just that frame;
+otherwise, they affect all frames as well as the defaults that apply to
+new frames.
+
+@tindex set-face-attribute
+@defun set-face-attribute face frame &rest arguments
+This function sets one or more attributes of face @var{face}
+for frame @var{frame}. If @var{frame} is @code{nil}, it sets
+the attribute for all frames, and the defaults for new frames.
+
+The extra arguments @var{arguments} specify the attributes to set, and
+the values for them. They should consist of alternating attribute names
+(such as @code{:family} or @code{:underline}) and corresponding values.
+Thus,
+
+@example
+(set-face-attribute 'foo nil
+ :width 'extended
+ :weight 'bold
+ :underline "red")
+@end example
+
+@noindent
+sets the attributes @code{:width}, @code{:weight} and @code{:underline}
+to the corresponding values.
+@end defun
+
+@tindex face-attribute
+@defun face-attribute face attribute &optional frame inherit
+This returns the value of the @var{attribute} attribute of face
+@var{face} on @var{frame}. If @var{frame} is @code{nil},
+that means the selected frame (@pxref{Input Focus}).
+
+If @var{frame} is @code{t}, the value is the default for
+@var{face} for new frames.
+
+If @var{inherit} is @code{nil}, only attributes directly defined by
+@var{face} are considered, so the return value may be
+@code{unspecified}, or a relative value. If @var{inherit} is
+non-@code{nil}, @var{face}'s definition of @var{attribute} is merged
+with the faces specified by its @code{:inherit} attribute; however the
+return value may still be @code{unspecified} or relative. If
+@var{inherit} is a face or a list of faces, then the result is further
+merged with that face (or faces), until it becomes specified and
+absolute.
+
+To ensure that the return value is always specified and absolute, use
+a value of @code{default} for @var{inherit}; this will resolve any
+unspecified or relative values by merging with the @code{default} face
+(which is always completely specified).
+
+For example,
+
+@example
+(face-attribute 'bold :weight)
+ @result{} bold
+@end example
+@end defun
+
+ The functions above did not exist before Emacs 21. For compatibility
+with older Emacs versions, you can use the following functions to set
+and examine the face attributes which existed in those versions.
+
+@tindex face-attribute-relative-p
+@defun face-attribute-relative-p attribute value
+This function returns non-@code{nil} if @var{value}, when used as
+the value of the face attribute @var{attribute}, is relative (that is,
+if it modifies an underlying or inherited value of @var{attribute}).
+@end defun
+
+@tindex merge-face-attribute
+@defun merge-face-attribute attribute value1 value2
+If @var{value1} is a relative value for the face attribute
+@var{attribute}, returns it merged with the underlying value
+@var{value2}; otherwise, if @var{value1} is an absolute value for the
+face attribute @var{attribute}, returns @var{value1} unchanged.
+@end defun
+
+@defun set-face-foreground face color &optional frame
+@defunx set-face-background face color &optional frame
+These functions set the foreground (or background, respectively) color
+of face @var{face} to @var{color}. The argument @var{color} should be a
+string, the name of a color.
+
+Certain shades of gray are implemented by stipple patterns on
+black-and-white screens.
+@end defun
+
+@defun set-face-stipple face pattern &optional frame
+This function sets the background stipple pattern of face @var{face}
+to @var{pattern}. The argument @var{pattern} should be the name of a
+stipple pattern defined by the X server, or actual bitmap data
+(@pxref{Face Attributes}), or @code{nil} meaning don't use stipple.
+
+Normally there is no need to pay attention to stipple patterns, because
+they are used automatically to handle certain shades of gray.
+@end defun
+
+@defun set-face-font face font &optional frame
+This function sets the font of face @var{face}. This actually sets
+the attributes @code{:family}, @code{:width}, @code{:height},
+@code{:weight}, and @code{:slant} according to the font name
+@var{font}.
+@end defun
+
+@defun set-face-bold-p face bold-p &optional frame
+This function specifies whether @var{face} should be bold. If
+@var{bold-p} is non-@code{nil}, that means yes; @code{nil} means no.
+This actually sets the @code{:weight} attribute.
+@end defun
+
+@defun set-face-italic-p face italic-p &optional frame
+This function specifies whether @var{face} should be italic. If
+@var{italic-p} is non-@code{nil}, that means yes; @code{nil} means no.
+This actually sets the @code{:slant} attribute.
+@end defun
+
+@defun set-face-underline-p face underline-p &optional frame
+This function sets the underline attribute of face @var{face}.
+Non-@code{nil} means do underline; @code{nil} means don't.
+@end defun
+
+@defun invert-face face &optional frame
+This function inverts the @code{:inverse-video} attribute of face
+@var{face}. If the attribute is @code{nil}, this function sets it to
+@code{t}, and vice versa.
+@end defun
+
+ These functions examine the attributes of a face. If you don't
+specify @var{frame}, they refer to the default data for new frames.
+They return the symbol @code{unspecified} if the face doesn't define any
+value for that attribute.
+
+@defun face-foreground face &optional frame inherit
+@defunx face-background face &optional frame
+These functions return the foreground color (or background color,
+respectively) of face @var{face}, as a string.
+
+If @var{inherit} is @code{nil}, only a color directly defined by the face is
+returned. If @var{inherit} is non-@code{nil}, any faces specified by its
+@code{:inherit} attribute are considered as well, and if @var{inherit}
+is a face or a list of faces, then they are also considered, until a
+specified color is found. To ensure that the return value is always
+specified, use a value of @code{default} for @var{inherit}.
+@end defun
+
+@defun face-stipple face &optional frame inherit
+This function returns the name of the background stipple pattern of face
+@var{face}, or @code{nil} if it doesn't have one.
+
+If @var{inherit} is @code{nil}, only a stipple directly defined by the
+face is returned. If @var{inherit} is non-@code{nil}, any faces
+specified by its @code{:inherit} attribute are considered as well, and
+if @var{inherit} is a face or a list of faces, then they are also
+considered, until a specified stipple is found. To ensure that the
+return value is always specified, use a value of @code{default} for
+@var{inherit}.
+@end defun
+
+@defun face-font face &optional frame
+This function returns the name of the font of face @var{face}.
+@end defun
+
+@defun face-bold-p face &optional frame
+This function returns @code{t} if @var{face} is bold---that is, if it is
+bolder than normal. It returns @code{nil} otherwise.
+@end defun
+
+@defun face-italic-p face &optional frame
+This function returns @code{t} if @var{face} is italic or oblique,
+@code{nil} otherwise.
+@end defun
+
+@defun face-underline-p face &optional frame
+This function returns the @code{:underline} attribute of face @var{face}.
+@end defun
+
+@defun face-inverse-video-p face &optional frame
+This function returns the @code{:inverse-video} attribute of face @var{face}.
+@end defun
+
+@node Displaying Faces
+@subsection Displaying Faces
+
+ Here are the ways to specify which faces to use for display of text:
+
+@itemize @bullet
+@item
+With defaults. The @code{default} face is used as the ultimate
+default for all text. (In Emacs 19 and 20, the @code{default}
+face is used only when no other face is specified.)
+
+@item
+For a mode line or header line, the face @code{mode-line} or
+@code{mode-line-inactive}, or @code{header-line}, is merged in just
+before @code{default}.
+
+@item
+With text properties. A character can have a @code{face} property; if
+so, the faces and face attributes specified there apply. @xref{Special
+Properties}.
+
+If the character has a @code{mouse-face} property, that is used instead
+of the @code{face} property when the mouse is ``near enough'' to the
+character.
+
+@item
+With overlays. An overlay can have @code{face} and @code{mouse-face}
+properties too; they apply to all the text covered by the overlay.
+
+@item
+With a region that is active. In Transient Mark mode, the region is
+highlighted with the face @code{region} (@pxref{Standard Faces}).
+
+@item
+With special glyphs. Each glyph can specify a particular face
+number. @xref{Glyphs}.
+@end itemize
+
+ If these various sources together specify more than one face for a
+particular character, Emacs merges the attributes of the various faces
+specified. For each attribute, Emacs tries first the face of any
+special glyph; then the face for region highlighting, if appropriate;
+then the faces specified by overlays, followed by those specified by
+text properties, then the @code{mode-line} or
+@code{mode-line-inactive} or @code{header-line} face (if in a mode
+line or a header line), and last the @code{default} face.
+
+ When multiple overlays cover one character, an overlay with higher
+priority overrides those with lower priority. @xref{Overlays}.
+
+@node Font Selection
+@subsection Font Selection
+
+ @dfn{Selecting a font} means mapping the specified face attributes for
+a character to a font that is available on a particular display. The
+face attributes, as determined by face merging, specify most of the
+font choice, but not all. Part of the choice depends on what character
+it is.
+
+ If the face specifies a fontset name, that fontset determines a
+pattern for fonts of the given charset. If the face specifies a font
+family, a font pattern is constructed.
+
+ Emacs tries to find an available font for the given face attributes
+and character's registry and encoding. If there is a font that matches
+exactly, it is used, of course. The hard case is when no available font
+exactly fits the specification. Then Emacs looks for one that is
+``close''---one attribute at a time. You can specify the order to
+consider the attributes. In the case where a specified font family is
+not available, you can specify a set of mappings for alternatives to
+try.
+
+@defvar face-font-selection-order
+@tindex face-font-selection-order
+This variable specifies the order of importance of the face attributes
+@code{:width}, @code{:height}, @code{:weight}, and @code{:slant}. The
+value should be a list containing those four symbols, in order of
+decreasing importance.
+
+Font selection first finds the best available matches for the first
+attribute listed; then, among the fonts which are best in that way, it
+searches for the best matches in the second attribute, and so on.
+
+The attributes @code{:weight} and @code{:width} have symbolic values in
+a range centered around @code{normal}. Matches that are more extreme
+(farther from @code{normal}) are somewhat preferred to matches that are
+less extreme (closer to @code{normal}); this is designed to ensure that
+non-normal faces contrast with normal ones, whenever possible.
+
+The default is @code{(:width :height :weight :slant)}, which means first
+find the fonts closest to the specified @code{:width}, then---among the
+fonts with that width---find a best match for the specified font height,
+and so on.
+
+One example of a case where this variable makes a difference is when the
+default font has no italic equivalent. With the default ordering, the
+@code{italic} face will use a non-italic font that is similar to the
+default one. But if you put @code{:slant} before @code{:height}, the
+@code{italic} face will use an italic font, even if its height is not
+quite right.
+@end defvar
+
+@defvar face-font-family-alternatives
+@tindex face-font-family-alternatives
+This variable lets you specify alternative font families to try, if a
+given family is specified and doesn't exist. Each element should have
+this form:
+
+@example
+(@var{family} @var{alternate-families}@dots{})
+@end example
+
+If @var{family} is specified but not available, Emacs will try the other
+families given in @var{alternate-families}, one by one, until it finds a
+family that does exist.
+@end defvar
+
+@defvar face-font-registry-alternatives
+@tindex face-font-registry-alternatives
+This variable lets you specify alternative font registries to try, if a
+given registry is specified and doesn't exist. Each element should have
+this form:
+
+@example
+(@var{registry} @var{alternate-registries}@dots{})
+@end example
+
+If @var{registry} is specified but not available, Emacs will try the
+other registries given in @var{alternate-registries}, one by one,
+until it finds a registry that does exist.
+@end defvar
+
+ Emacs can make use of scalable fonts, but by default it does not use
+them, since the use of too many or too big scalable fonts can crash
+XFree86 servers.
+
+@defvar scalable-fonts-allowed
+@tindex scalable-fonts-allowed
+This variable controls which scalable fonts to use. A value of
+@code{nil}, the default, means do not use scalable fonts. @code{t}
+means to use any scalable font that seems appropriate for the text.
+
+Otherwise, the value must be a list of regular expressions. Then a
+scalable font is enabled for use if its name matches any regular
+expression in the list. For example,
+
+@example
+(setq scalable-fonts-allowed '("muleindian-2$"))
+@end example
+
+@noindent
+allows the use of scalable fonts with registry @code{muleindian-2}.
+@end defvar
+
+@defun clear-face-cache &optional unload-p
+@tindex clear-face-cache
+This function clears the face cache for all frames.
+If @var{unload-p} is non-@code{nil}, that means to unload
+all unused fonts as well.
+@end defun
+
+@defvar face-font-rescale-alist
+This variable specifies scaling for certain faces. Its value should
+be a list of elements of the form
+
+@example
+(@var{fontname-regexp} . @var{scale-factor})
+@end example
+
+If @var{fontname-regexp} matches the font name that is about to be
+used, this says to choose a larger similar font according to the
+factor @var{scale-factor}. You would use this feature to normalize
+the font size if certain fonts are bigger or smaller than their
+nominal heights and widths would suggest.
+@end defvar
+
+@node Face Functions
+@subsection Functions for Working with Faces
+
+ Here are additional functions for creating and working with faces.
+
+@defun make-face name
+This function defines a new face named @var{name}, initially with all
+attributes @code{nil}. It does nothing if there is already a face named
+@var{name}.
+@end defun
+
+@defun face-list
+This function returns a list of all defined face names.
+@end defun
+
+@defun copy-face old-face new-name &optional frame new-frame
+This function defines a face named @var{new-name} as a copy of the existing
+face named @var{old-face}. It creates the face @var{new-name} if that
+doesn't already exist.
+
+If the optional argument @var{frame} is given, this function applies
+only to that frame. Otherwise it applies to each frame individually,
+copying attributes from @var{old-face} in each frame to @var{new-face}
+in the same frame.
+
+If the optional argument @var{new-frame} is given, then @code{copy-face}
+copies the attributes of @var{old-face} in @var{frame} to @var{new-name}
+in @var{new-frame}.
+@end defun
+
+@defun face-id face
+This function returns the face number of face @var{face}.
+@end defun
+
+@defun face-documentation face
+This function returns the documentation string of face @var{face}, or
+@code{nil} if none was specified for it.
+@end defun
+
+@defun face-equal face1 face2 &optional frame
+This returns @code{t} if the faces @var{face1} and @var{face2} have the
+same attributes for display.
+@end defun
+
+@defun face-differs-from-default-p face &optional frame
+This returns non-@code{nil} if the face @var{face} displays
+differently from the default face.
+@end defun
+
+@cindex face alias
+A @dfn{face alias} provides an equivalent name for a face. You can
+define a face alias by giving the alias symbol the @code{face-alias}
+property, with a value of the target face name. The following example
+makes @code{modeline} an alias for the @code{mode-line} face.
+
+@example
+(put 'modeline 'face-alias 'mode-line)
+@end example
+
+
+@node Auto Faces
+@subsection Automatic Face Assignment
+@cindex automatic face assignment
+@cindex faces, automatic choice
+
+@cindex Font-Lock mode
+ This hook is used for automatically assigning faces to text in the
+buffer. It is part of the implementation of Font-Lock mode.
+
+@tindex fontification-functions
+@defvar fontification-functions
+This variable holds a list of functions that are called by Emacs
+redisplay as needed to assign faces automatically to text in the buffer.
+
+The functions are called in the order listed, with one argument, a
+buffer position @var{pos}. Each function should attempt to assign faces
+to the text in the current buffer starting at @var{pos}.
+
+Each function should record the faces they assign by setting the
+@code{face} property. It should also add a non-@code{nil}
+@code{fontified} property for all the text it has assigned faces to.
+That property tells redisplay that faces have been assigned to that text
+already.
+
+It is probably a good idea for each function to do nothing if the
+character after @var{pos} already has a non-@code{nil} @code{fontified}
+property, but this is not required. If one function overrides the
+assignments made by a previous one, the properties as they are
+after the last function finishes are the ones that really matter.
+
+For efficiency, we recommend writing these functions so that they
+usually assign faces to around 400 to 600 characters at each call.
+@end defvar
+
+@node Font Lookup
+@subsection Looking Up Fonts
+
+@defun x-list-fonts pattern &optional face frame maximum
+This function returns a list of available font names that match
+@var{pattern}. If the optional arguments @var{face} and @var{frame} are
+specified, then the list is limited to fonts that are the same size as
+@var{face} currently is on @var{frame}.
+
+The argument @var{pattern} should be a string, perhaps with wildcard
+characters: the @samp{*} character matches any substring, and the
+@samp{?} character matches any single character. Pattern matching
+of font names ignores case.
+
+If you specify @var{face} and @var{frame}, @var{face} should be a face name
+(a symbol) and @var{frame} should be a frame.
+
+The optional argument @var{maximum} sets a limit on how many fonts to
+return. If this is non-@code{nil}, then the return value is truncated
+after the first @var{maximum} matching fonts. Specifying a small value
+for @var{maximum} can make this function much faster, in cases where
+many fonts match the pattern.
+@end defun
+
+@defun x-family-fonts &optional family frame
+@tindex x-family-fonts
+This function returns a list describing the available fonts for family
+@var{family} on @var{frame}. If @var{family} is omitted or @code{nil},
+this list applies to all families, and therefore, it contains all
+available fonts. Otherwise, @var{family} must be a string; it may
+contain the wildcards @samp{?} and @samp{*}.
+
+The list describes the display that @var{frame} is on; if @var{frame} is
+omitted or @code{nil}, it applies to the selected frame's display
+(@pxref{Input Focus}).
+
+The list contains a vector of the following form for each font:
+
+@example
+[@var{family} @var{width} @var{point-size} @var{weight} @var{slant}
+ @var{fixed-p} @var{full} @var{registry-and-encoding}]
+@end example
+
+The first five elements correspond to face attributes; if you
+specify these attributes for a face, it will use this font.
+
+The last three elements give additional information about the font.
+@var{fixed-p} is non-@code{nil} if the font is fixed-pitch.
+@var{full} is the full name of the font, and
+@var{registry-and-encoding} is a string giving the registry and
+encoding of the font.
+
+The result list is sorted according to the current face font sort order.
+@end defun
+
+@defun x-font-family-list &optional frame
+@tindex x-font-family-list
+This function returns a list of the font families available for
+@var{frame}'s display. If @var{frame} is omitted or @code{nil}, it
+describes the selected frame's display (@pxref{Input Focus}).
+
+The value is a list of elements of this form:
+
+@example
+(@var{family} . @var{fixed-p})
+@end example
+
+@noindent
+Here @var{family} is a font family, and @var{fixed-p} is
+non-@code{nil} if fonts of that family are fixed-pitch.
+@end defun
+
+@defvar font-list-limit
+@tindex font-list-limit
+This variable specifies maximum number of fonts to consider in font
+matching. The function @code{x-family-fonts} will not return more than
+that many fonts, and font selection will consider only that many fonts
+when searching a matching font for face attributes. The default is
+currently 100.
+@end defvar
+
+@node Fontsets
+@subsection Fontsets
+
+ A @dfn{fontset} is a list of fonts, each assigned to a range of
+character codes. An individual font cannot display the whole range of
+characters that Emacs supports, but a fontset can. Fontsets have names,
+just as fonts do, and you can use a fontset name in place of a font name
+when you specify the ``font'' for a frame or a face. Here is
+information about defining a fontset under Lisp program control.
+
+@defun create-fontset-from-fontset-spec fontset-spec &optional style-variant-p noerror
+This function defines a new fontset according to the specification
+string @var{fontset-spec}. The string should have this format:
+
+@smallexample
+@var{fontpattern}, @r{[}@var{charsetname}:@var{fontname}@r{]@dots{}}
+@end smallexample
+
+@noindent
+Whitespace characters before and after the commas are ignored.
+
+The first part of the string, @var{fontpattern}, should have the form of
+a standard X font name, except that the last two fields should be
+@samp{fontset-@var{alias}}.
+
+The new fontset has two names, one long and one short. The long name is
+@var{fontpattern} in its entirety. The short name is
+@samp{fontset-@var{alias}}. You can refer to the fontset by either
+name. If a fontset with the same name already exists, an error is
+signaled, unless @var{noerror} is non-@code{nil}, in which case this
+function does nothing.
+
+If optional argument @var{style-variant-p} is non-@code{nil}, that says
+to create bold, italic and bold-italic variants of the fontset as well.
+These variant fontsets do not have a short name, only a long one, which
+is made by altering @var{fontpattern} to indicate the bold or italic
+status.
+
+The specification string also says which fonts to use in the fontset.
+See below for the details.
+@end defun
+
+ The construct @samp{@var{charset}:@var{font}} specifies which font to
+use (in this fontset) for one particular character set. Here,
+@var{charset} is the name of a character set, and @var{font} is the font
+to use for that character set. You can use this construct any number of
+times in the specification string.
+
+ For the remaining character sets, those that you don't specify
+explicitly, Emacs chooses a font based on @var{fontpattern}: it replaces
+@samp{fontset-@var{alias}} with a value that names one character set.
+For the @acronym{ASCII} character set, @samp{fontset-@var{alias}} is replaced
+with @samp{ISO8859-1}.
+
+ In addition, when several consecutive fields are wildcards, Emacs
+collapses them into a single wildcard. This is to prevent use of
+auto-scaled fonts. Fonts made by scaling larger fonts are not usable
+for editing, and scaling a smaller font is not useful because it is
+better to use the smaller font in its own size, which Emacs does.
+
+ Thus if @var{fontpattern} is this,
+
+@example
+-*-fixed-medium-r-normal-*-24-*-*-*-*-*-fontset-24
+@end example
+
+@noindent
+the font specification for @acronym{ASCII} characters would be this:
+
+@example
+-*-fixed-medium-r-normal-*-24-*-ISO8859-1
+@end example
+
+@noindent
+and the font specification for Chinese GB2312 characters would be this:
+
+@example
+-*-fixed-medium-r-normal-*-24-*-gb2312*-*
+@end example
+
+ You may not have any Chinese font matching the above font
+specification. Most X distributions include only Chinese fonts that
+have @samp{song ti} or @samp{fangsong ti} in the @var{family} field. In
+such a case, @samp{Fontset-@var{n}} can be specified as below:
+
+@smallexample
+Emacs.Fontset-0: -*-fixed-medium-r-normal-*-24-*-*-*-*-*-fontset-24,\
+ chinese-gb2312:-*-*-medium-r-normal-*-24-*-gb2312*-*
+@end smallexample
+
+@noindent
+Then, the font specifications for all but Chinese GB2312 characters have
+@samp{fixed} in the @var{family} field, and the font specification for
+Chinese GB2312 characters has a wild card @samp{*} in the @var{family}
+field.
+
+@defun set-fontset-font name character fontname &optional frame
+This function modifies the existing fontset @var{name} to
+use the font name @var{fontname} for the character @var{character}.
+
+If @var{name} is @code{nil}, this function modifies the default
+fontset, whose short name is @samp{fontset-default}.
+
+@var{character} may be a cons; @code{(@var{from} . @var{to})}, where
+@var{from} and @var{to} are non-generic characters. In that case, use
+@var{fontname} for all characters in the range @var{from} and @var{to}
+(inclusive).
+
+@var{character} may be a charset. In that case, use
+@var{fontname} for all character in the charsets.
+
+@var{fontname} may be a cons; @code{(@var{family} . @var{registry})},
+where @var{family} is a family name of a font (possibly including a
+foundry name at the head), @var{registry} is a registry name of a font
+(possibly including an encoding name at the tail).
+
+For instance, this changes the default fontset to use a font of which
+registry name is @samp{JISX0208.1983} for all characters belonging to
+the charset @code{japanese-jisx0208}.
+
+@smallexample
+(set-fontset-font nil 'japanese-jisx0208 '(nil . "JISX0208.1983"))
+@end smallexample
+@end defun
+
+@defun char-displayable-p char
+This function returns @code{t} if Emacs ought to be able to display
+@var{char}. More precisely, if the selected frame's fontset has a
+font to display the character set that @var{char} belongs to.
+
+Fontsets can specify a font on a per-character basis; when the fontset
+does that, this function's value may not be accurate.
+@end defun
+
+@node Fringes
+@section Fringes
+@cindex Fringes
+
+ The @dfn{fringes} of a window are thin vertical strips down the
+sides that are used for displaying bitmaps that indicate truncation,
+continuation, horizontal scrolling, and the overlay arrow.
+
+@menu
+* Fringe Size/Pos:: Specifying where to put the window fringes.
+* Fringe Bitmaps:: Displaying bitmaps in the window fringes.
+* Customizing Bitmaps:: Specifying your own bitmaps to use in the fringes.
+* Overlay Arrow:: Display of an arrow to indicate position.
+@end menu
+
+@node Fringe Size/Pos
+@subsection Fringe Size and Position
+
+ Here's how to control the position and width of the window fringes.
+
+@defvar fringes-outside-margins
+If the value is non-@code{nil}, the frames appear outside the display
+margins. The fringes normally appear between the display margins and
+the window text. It works to set @code{fringes-outside-margins}
+buffer-locally. @xref{Display Margins}.
+@end defvar
+
+@defvar left-fringe-width
+This variable, if non-@code{nil}, specifies the width of the left
+fringe in pixels.
+@end defvar
+
+@defvar right-fringe-width
+This variable, if non-@code{nil}, specifies the width of the right
+fringe in pixels.
+@end defvar
+
+ The values of these variables take effect when you display the
+buffer in a window. If you change them while the buffer is visible,
+you can call @code{set-window-buffer} to display it once again in the
+same window, to make the changes take effect.
+
+@defun set-window-fringes window left &optional right outside-margins
+This function sets the fringe widths of window @var{window}.
+If @var{window} is @code{nil}, the selected window is used.
+
+The argument @var{left} specifies the width in pixels of the left
+fringe, and likewise @var{right} for the right fringe. A value of
+@code{nil} for either one stands for the default width. If
+@var{outside-margins} is non-@code{nil}, that specifies that fringes
+should appear outside of the display margins.
+@end defun
+
+@defun window-fringes &optional window
+This function returns information about the fringes of a window
+@var{window}. If @var{window} is omitted or @code{nil}, the selected
+window is used. The value has the form @code{(@var{left-width}
+@var{right-width} @var{outside-margins})}.
+@end defun
+
+@defvar overflow-newline-into-fringe
+If this is non-@code{nil}, lines exactly as wide as the window (not
+counting the final newline character) are not continued. Instead,
+when point is at the end of the line, the cursor appears in the right
+fringe.
+@end defvar
+
+@node Fringe Bitmaps
+@subsection Fringe Bitmaps
+@cindex fringe bitmaps
+@cindex bitmaps, fringe
+
+ The @dfn{fringe bitmaps} are tiny icons Emacs displays in the window
+fringe (on a graphic display) to indicate truncated or continued
+lines, buffer boundaries, overlay arrow, etc. The fringe bitmaps are
+shared by all frames and windows. You can redefine the built-in
+fringe bitmaps, and you can define new fringe bitmaps.
+
+ The way to display a bitmap in the left or right fringes for a given
+line in a window is by specifying the @code{display} property for one
+of the characters that appears in it. Use a display specification of
+the form @code{(left-fringe @var{bitmap} [@var{face}])} or
+@code{(right-fringe @var{bitmap} [@var{face}])} (@pxref{Display
+Property}). Here, @var{bitmap} is a symbol identifying the bitmap you
+want, and @var{face} (which is optional) is the name of the face whose
+colors should be used for displaying the bitmap, instead of the
+default @code{fringe} face. @var{face} is automatically merged with
+the @code{fringe} face, so normally @var{face} need only specify the
+foreground color for the bitmap.
+
+ These symbols identify the standard fringe bitmaps. Evaluate
+@code{(require 'fringe)} to define them. Fringe bitmap symbols have
+their own name space.
+
+@table @asis
+@item Truncation and continuation line bitmaps:
+@code{left-truncation}, @code{right-truncation},
+@code{continued-line}, @code{continuation-line}.
+
+@item Buffer indication bitmaps:
+@code{up-arrow}, @code{down-arrow},
+@code{top-left-angle}, @code{top-right-angle},
+@code{bottom-left-angle}, @code{bottom-right-angle},
+@code{left-bracket}, @code{right-bracket}.
+
+@item Empty line indication bitmap:
+@code{empty-line}.
+
+@item Overlay arrow bitmap:
+@code{overlay-arrow}.
+
+@item Bitmaps for displaying the cursor in right fringe:
+@code{filled-box-cursor}, @code{hollow-box-cursor}, @code{hollow-square},
+@code{bar-cursor}, @code{hbar-cursor}.
+@end table
+
+@defun fringe-bitmaps-at-pos &optional pos window
+This function returns the fringe bitmaps of the display line
+containing position @var{pos} in window @var{window}. The return
+value has the form @code{(@var{left} @var{right} @var{ov})}, where @var{left}
+is the symbol for the fringe bitmap in the left fringe (or @code{nil}
+if no bitmap), @var{right} is similar for the right fringe, and @var{ov}
+is non-@code{nil} if there is an overlay arrow in the left fringe.
+
+The value is @code{nil} if @var{pos} is not visible in @var{window}.
+If @var{window} is @code{nil}, that stands for the selected window.
+If @var{pos} is @code{nil}, that stands for the value of point in
+@var{window}.
+@end defun
+
+@node Customizing Bitmaps
+@subsection Customizing Fringe Bitmaps
+
+@defun define-fringe-bitmap bitmap bits &optional height width align
+This function defines the symbol @var{bitmap} as a new fringe bitmap,
+or replaces an existing bitmap with that name.
+
+The argument @var{bits} specifies the image to use. It should be
+either a string or a vector of integers, where each element (an
+integer) corresponds to one row of the bitmap. Each bit of an integer
+corresponds to one pixel of the bitmap, where the low bit corresponds
+to the rightmost pixel of the bitmap.
+
+The height is normally the length of @var{bits}. However, you
+can specify a different height with non-@code{nil} @var{height}. The width
+is normally 8, but you can specify a different width with non-@code{nil}
+@var{width}. The width must be an integer between 1 and 16.
+
+The argument @var{align} specifies the positioning of the bitmap
+relative to the range of rows where it is used; the default is to
+center the bitmap. The allowed values are @code{top}, @code{center},
+or @code{bottom}.
+
+The @var{align} argument may also be a list @code{(@var{align}
+@var{periodic})} where @var{align} is interpreted as described above.
+If @var{periodic} is non-@code{nil}, it specifies that the rows in
+@code{bits} should be repeated enough times to reach the specified
+height.
+
+The return value on success is an integer identifying the new bitmap.
+You should save that integer in a variable so it can be used to select
+this bitmap.
+
+This function signals an error if there are no more free bitmap slots.
+@end defun
+
+@defun destroy-fringe-bitmap bitmap
+This function destroy the fringe bitmap identified by @var{bitmap}.
+If @var{bitmap} identifies a standard fringe bitmap, it actually
+restores the standard definition of that bitmap, instead of
+eliminating it entirely.
+@end defun
+
+@defun set-fringe-bitmap-face bitmap &optional face
+This sets the face for the fringe bitmap @var{bitmap} to @var{face}.
+If @var{face} is @code{nil}, it selects the @code{fringe} face. The
+bitmap's face controls the color to draw it in.
+
+@var{face} is merged with the @code{fringe} face, so normally
+@var{face} should specify only the foreground color.
+@end defun
+
+@node Overlay Arrow
+@subsection The Overlay Arrow
+@cindex overlay arrow
+
+ The @dfn{overlay arrow} is useful for directing the user's attention
+to a particular line in a buffer. For example, in the modes used for
+interface to debuggers, the overlay arrow indicates the line of code
+about to be executed. This feature has nothing to do with
+@dfn{overlays} (@pxref{Overlays}).
+
+@defvar overlay-arrow-string
+This variable holds the string to display to call attention to a
+particular line, or @code{nil} if the arrow feature is not in use.
+On a graphical display the contents of the string are ignored; instead a
+glyph is displayed in the fringe area to the left of the display area.
+@end defvar
+
+@defvar overlay-arrow-position
+This variable holds a marker that indicates where to display the overlay
+arrow. It should point at the beginning of a line. On a non-graphical
+display the arrow text
+appears at the beginning of that line, overlaying any text that would
+otherwise appear. Since the arrow is usually short, and the line
+usually begins with indentation, normally nothing significant is
+overwritten.
+
+The overlay string is displayed only in the buffer that this marker
+points into. Thus, only one buffer can have an overlay arrow at any
+given time.
+@c !!! overlay-arrow-position: but the overlay string may remain in the display
+@c of some other buffer until an update is required. This should be fixed
+@c now. Is it?
+@end defvar
+
+ You can do a similar job by creating an overlay with a
+@code{before-string} property. @xref{Overlay Properties}.
+
+ You can define multiple overlay arrows via the variable
+@code{overlay-arrow-variable-list}.
+
+@defvar overlay-arrow-variable-list
+This variable's value is a list of variables, each of which specifies
+the position of an overlay arrow. The variable
+@code{overlay-arrow-position} has its normal meaning because it is on
+this list.
+@end defvar
+
+Each variable on this list can have properties
+@code{overlay-arrow-string} and @code{overlay-arrow-bitmap} that
+specify an overlay arrow string (for text-only terminals) or fringe
+bitmap (for graphical terminals) to display at the corresponding
+overlay arrow position. If either property is not set, the default
+(@code{overlay-arrow-string} or @code{overlay-arrow-fringe-bitmap}) is
+used.
+
+@node Scroll Bars
+@section Scroll Bars
+
+Normally the frame parameter @code{vertical-scroll-bars} controls
+whether the windows in the frame have vertical scroll bars, and
+whether they are on the left or right. The frame parameter
+@code{scroll-bar-width} specifies how wide they are (@code{nil}
+meaning the default). @xref{Window Frame Parameters}.
+
+@defun frame-current-scroll-bars &optional frame
+This function reports the scroll bar type settings for frame
+@var{frame}. The value is a cons cell
+@code{(@var{vertical-type} .@: @var{horizontal-type})}, where
+@var{vertical-type} is either @code{left}, @code{right}, or @code{nil}
+(which means no scroll bar.) @var{horizontal-type} is meant to
+specify the horizontal scroll bar type, but since they are not
+implemented, it is always @code{nil}.
+@end defun
+
+@vindex vertical-scroll-bar
+ You can enable or disable scroll bars for a particular buffer,
+by setting the variable @code{vertical-scroll-bar}. This variable
+automatically becomes buffer-local when set. The possible values are
+@code{left}, @code{right}, @code{t}, which means to use the
+frame's default, and @code{nil} for no scroll bar.
+
+ You can also control this for individual windows. Call the function
+@code{set-window-scroll-bars} to specify what to do for a specific window:
+
+@defun set-window-scroll-bars window width &optional vertical-type horizontal-type
+This function sets the width and type of scroll bars for window
+@var{window}.
+
+@var{width} specifies the scroll bar width in pixels (@code{nil} means
+use the width specified for the frame). @var{vertical-type} specifies
+whether to have a vertical scroll bar and, if so, where. The possible
+values are @code{left}, @code{right} and @code{nil}, just like the
+values of the @code{vertical-scroll-bars} frame parameter.
+
+The argument @var{horizontal-type} is meant to specify whether and
+where to have horizontal scroll bars, but since they are not
+implemented, it has no effect. If @var{window} is @code{nil}, the
+selected window is used.
+@end defun
+
+@defun window-scroll-bars &optional window
+Report the width and type of scroll bars specified for @var{window}.
+If @var{window} is omitted or @code{nil}, the selected window is used.
+The value is a list of the form @code{(@var{width}
+@var{cols} @var{vertical-type} @var{horizontal-type})}. The value
+@var{width} is the value that was specified for the width (which may
+be @code{nil}); @var{cols} is the number of columns that the scroll
+bar actually occupies.
+
+@var{horizontal-type} is not actually meaningful.
+@end defun
+
+If you don't specify these values for a window with
+@code{set-window-scroll-bars}, the buffer-local variables
+@code{scroll-bar-mode} and @code{scroll-bar-width} in the buffer being
+displayed control the window's vertical scroll bars. The function
+@code{set-window-buffer} examines these variables. If you change them
+in a buffer that is already visible in a window, you can make the
+window take note of the new values by calling @code{set-window-buffer}
+specifying the same buffer that is already displayed.
+
+@defvar scroll-bar-mode
+This variable, always local in all buffers, controls whether and where
+to put scroll bars in windows displaying the buffer. The possible values
+are @code{nil} for no scroll bar, @code{left} to put a scroll bar on
+the left, and @code{right} to put a scroll bar on the right.
+@end defvar
+
+@defun window-current-scroll-bars &optional window
+This function reports the scroll bar type for window @var{window}.
+If @var{window} is omitted or @code{nil}, the selected window is used.
+The value is a cons cell
+@code{(@var{vertical-type} .@: @var{horizontal-type})}. Unlike
+@code{window-scroll-bars}, this reports the scroll bar type actually
+used, once frame defaults and @code{scroll-bar-mode} are taken into
+account.
+@end defun
+
+@defvar scroll-bar-width
+This variable, always local in all buffers, specifies the width of the
+buffer's scroll bars, measured in pixels. A value of @code{nil} means
+to use the value specified by the frame.
+@end defvar
+
+@node Pointer Shape
+@section Pointer Shape
+
+ Normally, the mouse pointer has the @code{text} shape over text and
+the @code{arrow} shape over window areas which do not correspond to
+any buffer text. You can specify the mouse pointer shape over text or
+images via the @code{pointer} text property, and for images with the
+@code{:pointer} and @code{:map} image properties.
+
+ The available pointer shapes are: @code{text} (or @code{nil}),
+@code{arrow}, @code{hand}, @code{vdrag}, @code{hdrag},
+@code{modeline}, and @code{hourglass}.
+
+@defvar void-text-area-pointer
+@tindex void-text-area-pointer
+This variable specifies the mouse pointer shape in void text areas,
+i.e. the areas after the end of a line or below the last line in the
+buffer. The default is to use the @code{arrow} (non-text) pointer.
+@end defvar
+
+@node Display Property
+@section The @code{display} Property
+@cindex display specification
+@kindex display @r{(text property)}
+
+ The @code{display} text property (or overlay property) is used to
+insert images into text, and also control other aspects of how text
+displays. The value of the @code{display} property should be a
+display specification, or a list or vector containing several display
+specifications.
+
+ Some kinds of @code{display} properties specify something to display
+instead of the text that has the property. In this case, ``the text''
+means all the consecutive characters that have the same Lisp object as
+their @code{display} property; these characters are replaced as a
+single unit. By contrast, characters that have similar but distinct
+Lisp objects as their @code{display} properties are handled
+separately. Here's a function that illustrates this point:
+
+@smallexample
+(defun foo ()
+ (goto-char (point-min))
+ (dotimes (i 5)
+ (let ((string (concat "A")))
+ (put-text-property (point) (1+ (point)) 'display string)
+ (forward-char 1)
+ (put-text-property (point) (1+ (point)) 'display string)
+ (forward-char 1))))
+@end smallexample
+
+@noindent
+It gives each of the first ten characters in the buffer string
+@code{"A"} as the @code{display} property, but they don't all get the
+same string. The first two characters get the same string, so they
+together are replaced with one @samp{A}. The next two characters get
+a second string, so they together are replaced with one @samp{A}.
+Likewise for each following pair of characters. Thus, the ten
+characters appear as five A's. This function would have the same
+results:
+
+@smallexample
+(defun foo ()
+ (goto-char (point-min))
+ (dotimes (i 5)
+ (let ((string (concat "A")))
+ (put-text-property (point) (2+ (point)) 'display string)
+ (put-text-property (point) (1+ (point)) 'display string)
+ (forward-char 2))))
+@end smallexample
+
+@noindent
+This illustrates that what matters is the property value for
+each character. If two consecutive characters have the same
+object as the @code{display} property value, it's irrelevant
+whether they got this property from a single call to
+@code{put-text-property} or from two different calls.
+
+ The rest of this section describes several kinds of
+display specifications and what they mean.
+
+@menu
+* Specified Space:: Displaying one space with a specified width.
+* Pixel Specification:: Specifying space width or height in pixels.
+* Other Display Specs:: Displaying an image; magnifying text; moving it
+ up or down on the page; adjusting the width
+ of spaces within text.
+* Display Margins:: Displaying text or images to the side of the main text.
+@end menu
+
+@node Specified Space
+@subsection Specified Spaces
+@cindex spaces, specified height or width
+@cindex specified spaces
+@cindex variable-width spaces
+
+ To display a space of specified width and/or height, use a display
+specification of the form @code{(space . @var{props})}, where
+@var{props} is a property list (a list of alternating properties and
+values). You can put this property on one or more consecutive
+characters; a space of the specified height and width is displayed in
+place of @emph{all} of those characters. These are the properties you
+can use in @var{props} to specify the weight of the space:
+
+@table @code
+@item :width @var{width}
+If @var{width} is an integer or floating point number, it specifies
+that the space width should be @var{width} times the normal character
+width. @var{width} can also be a @dfn{pixel width} specification
+(@pxref{Pixel Specification}).
+
+@item :relative-width @var{factor}
+Specifies that the width of the stretch should be computed from the
+first character in the group of consecutive characters that have the
+same @code{display} property. The space width is the width of that
+character, multiplied by @var{factor}.
+
+@item :align-to @var{hpos}
+Specifies that the space should be wide enough to reach @var{hpos}.
+If @var{hpos} is a number, it is measured in units of the normal
+character width. @var{hpos} can also be a @dfn{pixel width}
+specification (@pxref{Pixel Specification}).
+@end table
+
+ You should use one and only one of the above properties. You can
+also specify the height of the space, with these properties:
+
+@table @code
+@item :height @var{height}
+Specifies the height of the space.
+If @var{height} is an integer or floating point number, it specifies
+that the space height should be @var{height} times the normal character
+height. The @var{height} may also be a @dfn{pixel height} specification
+(@pxref{Pixel Specification}).
+
+@item :relative-height @var{factor}
+Specifies the height of the space, multiplying the ordinary height
+of the text having this display specification by @var{factor}.
+
+@item :ascent @var{ascent}
+If the value of @var{ascent} is a non-negative number no greater than
+100, it specifies that @var{ascent} percent of the height of the space
+should be considered as the ascent of the space---that is, the part
+above the baseline. The ascent may also be specified in pixel units
+with a @dfn{pixel ascent} specification (@pxref{Pixel Specification}).
+
+@end table
+
+ Don't use both @code{:height} and @code{:relative-height} together.
+
+ The @code{:width} and @code{:align-to} properties are supported on
+non-graphic terminals, but the other space properties in this section
+are not.
+
+@node Pixel Specification
+@subsection Pixel Specification for Spaces
+@cindex spaces, pixel specification
+
+ The value of the @code{:width}, @code{:align-to}, @code{:height},
+and @code{:ascent} properties can be a special kind of expression that
+is evaluated during redisplay. The result of the evaluation is used
+as an absolute number of pixels.
+
+ The following expressions are supported:
+
+@smallexample
+@group
+ @var{expr} ::= @var{num} | (@var{num}) | @var{unit} | @var{elem} | @var{pos} | @var{image} | @var{form}
+ @var{num} ::= @var{integer} | @var{float} | @var{symbol}
+ @var{unit} ::= in | mm | cm | width | height
+@end group
+@group
+ @var{elem} ::= left-fringe | right-fringe | left-margin | right-margin
+ | scroll-bar | text
+ @var{pos} ::= left | center | right
+ @var{form} ::= (@var{num} . @var{expr}) | (@var{op} @var{expr} ...)
+ @var{op} ::= + | -
+@end group
+@end smallexample
+
+ The form @var{num} specifies a fraction of the default frame font
+height or width. The form @code{(@var{num})} specifies an absolute
+number of pixels. If @var{num} is a symbol, @var{symbol}, its
+buffer-local variable binding is used.
+
+ The @code{in}, @code{mm}, and @code{cm} units specify the number of
+pixels per inch, millimeter, and centimeter, respectively. The
+@code{width} and @code{height} units correspond to the default width
+and height of the current face. An image specification @code{image}
+corresponds to the width or height of the image.
+
+ The @code{left-fringe}, @code{right-fringe}, @code{left-margin},
+@code{right-margin}, @code{scroll-bar}, and @code{text} elements
+specify to the width of the corresponding area of the window.
+
+ The @code{left}, @code{center}, and @code{right} positions can be
+used with @code{:align-to} to specify a position relative to the left
+edge, center, or right edge of the text area.
+
+ Any of the above window elements (except @code{text}) can also be
+used with @code{:align-to} to specify that the position is relative to
+the left edge of the given area. Once the base offset for a relative
+position has been set (by the first occurrence of one of these
+symbols), further occurrences of these symbols are interpreted as the
+width of the specified area. For example, to align to the center of
+the left-margin, use
+
+@example
+:align-to (+ left-margin (0.5 . left-margin))
+@end example
+
+ If no specific base offset is set for alignment, it is always relative
+to the left edge of the text area. For example, @samp{:align-to 0} in a
+header-line aligns with the first text column in the text area.
+
+ A value of the form @code{(@var{num} . @var{expr})} stands for the
+product of the values of @var{num} and @var{expr}. For example,
+@code{(2 . in)} specifies a width of 2 inches, while @code{(0.5 .
+@var{image})} specifies half the width (or height) of the specified
+image.
+
+ The form @code{(+ @var{expr} ...)} adds up the value of the
+expressions. The form @code{(- @var{expr} ...)} negates or subtracts
+the value of the expressions.
+
+@node Other Display Specs
+@subsection Other Display Specifications
+
+ Here are the other sorts of display specifications that you can use
+in the @code{display} text property.
+
+@table @code
+@item @var{string}
+Display @var{string} instead of the text that has this property.
+
+@item (image . @var{image-props})
+This kind of display specification is an image descriptor (@pxref{Images}).
+When used as a display specification, it means to display the image
+instead of the text that has the display specification.
+
+@item (slice @var{x} @var{y} @var{width} @var{height})
+This specification together with @code{image} specifies a @dfn{slice}
+(a partial area) of the image to display. The elements @var{y} and
+@var{x} specify the top left corner of the slice, within the image;
+@var{width} and @var{height} specify the width and height of the
+slice. Integer values are numbers of pixels. A floating point number
+in the range 0.0--1.0 stands for that fraction of the width or height
+of the entire image.
+
+@item ((margin nil) @var{string})
+@itemx @var{string}
+A display specification of this form means to display @var{string}
+instead of the text that has the display specification, at the same
+position as that text. This is a special case of marginal display
+(@pxref{Display Margins}).
+
+Recursive display specifications are not supported---string display
+specifications must not have @code{display} properties themselves.
+
+@item (space-width @var{factor})
+This display specification affects all the space characters within the
+text that has the specification. It displays all of these spaces
+@var{factor} times as wide as normal. The element @var{factor} should
+be an integer or float. Characters other than spaces are not affected
+at all; in particular, this has no effect on tab characters.
+
+@item (height @var{height})
+This display specification makes the text taller or shorter.
+Here are the possibilities for @var{height}:
+
+@table @asis
+@item @code{(+ @var{n})}
+This means to use a font that is @var{n} steps larger. A ``step'' is
+defined by the set of available fonts---specifically, those that match
+what was otherwise specified for this text, in all attributes except
+height. Each size for which a suitable font is available counts as
+another step. @var{n} should be an integer.
+
+@item @code{(- @var{n})}
+This means to use a font that is @var{n} steps smaller.
+
+@item a number, @var{factor}
+A number, @var{factor}, means to use a font that is @var{factor} times
+as tall as the default font.
+
+@item a symbol, @var{function}
+A symbol is a function to compute the height. It is called with the
+current height as argument, and should return the new height to use.
+
+@item anything else, @var{form}
+If the @var{height} value doesn't fit the previous possibilities, it is
+a form. Emacs evaluates it to get the new height, with the symbol
+@code{height} bound to the current specified font height.
+@end table
+
+@item (raise @var{factor})
+This kind of display specification raises or lowers the text
+it applies to, relative to the baseline of the line.
+
+@var{factor} must be a number, which is interpreted as a multiple of the
+height of the affected text. If it is positive, that means to display
+the characters raised. If it is negative, that means to display them
+lower down.
+
+If the text also has a @code{height} display specification, that does
+not affect the amount of raising or lowering, which is based on the
+faces used for the text.
+@end table
+
+ You can make any display specification conditional. To do that,
+package it in another list of the form @code{(when @var{condition} .
+@var{spec})}. Then the specification @var{spec} applies only when
+@var{condition} evaluates to a non-@code{nil} value. During the
+evaluation, @code{object} is bound to the string or buffer having the
+conditional @code{display} property. @code{position} and
+@code{buffer-position} are bound to the position within @code{object}
+and the buffer position where the @code{display} property was found,
+respectively. Both positions can be different when @code{object} is a
+string.
+
+@node Display Margins
+@subsection Displaying in the Margins
+@cindex display margins
+@cindex margins, display
+
+ A buffer can have blank areas called @dfn{display margins} on the left
+and on the right. Ordinary text never appears in these areas, but you
+can put things into the display margins using the @code{display}
+property.
+
+ To put text in the left or right display margin of the window, use a
+display specification of the form @code{(margin right-margin)} or
+@code{(margin left-margin)} on it. To put an image in a display margin,
+use that display specification along with the display specification for
+the image. Unfortunately, there is currently no way to make
+text or images in the margin mouse-sensitive.
+
+ If you put such a display specification directly on text in the
+buffer, the specified margin display appears @emph{instead of} that
+buffer text itself. To put something in the margin @emph{in
+association with} certain buffer text without preventing or altering
+the display of that text, put a @code{before-string} property on the
+text and put the display specification on the contents of the
+before-string.
+
+ Before the display margins can display anything, you must give
+them a nonzero width. The usual way to do that is to set these
+variables:
+
+@defvar left-margin-width
+@tindex left-margin-width
+This variable specifies the width of the left margin.
+It is buffer-local in all buffers.
+@end defvar
+
+@defvar right-margin-width
+@tindex right-margin-width
+This variable specifies the width of the right margin.
+It is buffer-local in all buffers.
+@end defvar
+
+ Setting these variables does not immediately affect the window. These
+variables are checked when a new buffer is displayed in the window.
+Thus, you can make changes take effect by calling
+@code{set-window-buffer}.
+
+ You can also set the margin widths immediately.
+
+@defun set-window-margins window left &optional right
+@tindex set-window-margins
+This function specifies the margin widths for window @var{window}.
+The argument @var{left} controls the left margin and
+@var{right} controls the right margin (default @code{0}).
+@end defun
+
+@defun window-margins &optional window
+@tindex window-margins
+This function returns the left and right margins of @var{window}
+as a cons cell of the form @code{(@var{left} . @var{right})}.
+If @var{window} is @code{nil}, the selected window is used.
+@end defun
+
+@node Images
+@section Images
+@cindex images in buffers
+
+ To display an image in an Emacs buffer, you must first create an image
+descriptor, then use it as a display specifier in the @code{display}
+property of text that is displayed (@pxref{Display Property}).
+
+ Emacs can display a number of different image formats; some of them
+are supported only if particular support libraries are installed on
+your machine. In some environments, Emacs can load image
+libraries on demand; if so, the variable @code{image-library-alist}
+can be used to modify the set of known names for these dynamic
+libraries (though it is not possible to add new image formats).
+
+ The supported image formats include XBM, XPM (this requires the
+libraries @code{libXpm} version 3.4k and @code{libz}), GIF (requiring
+@code{libungif} 4.1.0), Postscript, PBM, JPEG (requiring the
+@code{libjpeg} library version v6a), TIFF (requiring @code{libtiff}
+v3.4), and PNG (requiring @code{libpng} 1.0.2).
+
+ You specify one of these formats with an image type symbol. The image
+type symbols are @code{xbm}, @code{xpm}, @code{gif}, @code{postscript},
+@code{pbm}, @code{jpeg}, @code{tiff}, and @code{png}.
+
+@defvar image-types
+This variable contains a list of those image type symbols that are
+potentially supported in the current configuration.
+@emph{Potentially} here means that Emacs knows about the image types,
+not necessarily that they can be loaded (they could depend on
+unavailable dynamic libraries, for example).
+
+To know which image types are really available, use
+@code{image-type-available-p}.
+@end defvar
+
+@defvar image-library-alist
+This in an alist of image types vs external libraries needed to
+display them.
+
+Each element is a list @code{(@var{image-type} @var{library}...)},
+where the car is a supported image format from @code{image-types}, and
+the rest are strings giving alternate filenames for the corresponding
+external libraries to load.
+
+Emacs tries to load the libraries in the order they appear on the
+list; if none is loaded, the running session of Emacs won't support
+the image type. @code{pbm} and @code{xbm} don't need to be listed;
+they're always supported.
+
+This variable is ignored if the image libraries are statically linked
+into Emacs.
+@end defvar
+
+@defun image-type-available-p type
+@findex image-type-available-p
+
+This function returns non-@code{nil} if image type @var{type} is
+available, i.e., if images of this type can be loaded and displayed in
+Emacs. @var{type} should be one of the types contained in
+@code{image-types}.
+
+For image types whose support libraries are statically linked, this
+function always returns @code{t}; for other image types, it returns
+@code{t} if the dynamic library could be loaded, @code{nil} otherwise.
+@end defun
+
+@menu
+* Image Descriptors:: How to specify an image for use in @code{:display}.
+* XBM Images:: Special features for XBM format.
+* XPM Images:: Special features for XPM format.
+* GIF Images:: Special features for GIF format.
+* Postscript Images:: Special features for Postscript format.
+* Other Image Types:: Various other formats are supported.
+* Defining Images:: Convenient ways to define an image for later use.
+* Showing Images:: Convenient ways to display an image once it is defined.
+* Image Cache:: Internal mechanisms of image display.
+@end menu
+
+@node Image Descriptors
+@subsection Image Descriptors
+@cindex image descriptor
+
+ An image description is a list of the form @code{(image
+. @var{props})}, where @var{props} is a property list containing
+alternating keyword symbols (symbols whose names start with a colon) and
+their values. You can use any Lisp object as a property, but the only
+properties that have any special meaning are certain symbols, all of
+them keywords.
+
+ Every image descriptor must contain the property @code{:type
+@var{type}} to specify the format of the image. The value of @var{type}
+should be an image type symbol; for example, @code{xpm} for an image in
+XPM format.
+
+ Here is a list of other properties that are meaningful for all image
+types:
+
+@table @code
+@item :file @var{file}
+The @code{:file} property says to load the image from file
+@var{file}. If @var{file} is not an absolute file name, it is expanded
+in @code{data-directory}.
+
+@item :data @var{data}
+The @code{:data} property says the actual contents of the image.
+Each image must use either @code{:data} or @code{:file}, but not both.
+For most image types, the value of the @code{:data} property should be a
+string containing the image data; we recommend using a unibyte string.
+
+Before using @code{:data}, look for further information in the section
+below describing the specific image format. For some image types,
+@code{:data} may not be supported; for some, it allows other data types;
+for some, @code{:data} alone is not enough, so you need to use other
+image properties along with @code{:data}.
+
+@item :margin @var{margin}
+The @code{:margin} property specifies how many pixels to add as an
+extra margin around the image. The value, @var{margin}, must be a
+non-negative number, or a pair @code{(@var{x} . @var{y})} of such
+numbers. If it is a pair, @var{x} specifies how many pixels to add
+horizontally, and @var{y} specifies how many pixels to add vertically.
+If @code{:margin} is not specified, the default is zero.
+
+@item :ascent @var{ascent}
+The @code{:ascent} property specifies the amount of the image's
+height to use for its ascent---that is, the part above the baseline.
+The value, @var{ascent}, must be a number in the range 0 to 100, or
+the symbol @code{center}.
+
+If @var{ascent} is a number, that percentage of the image's height is
+used for its ascent.
+
+If @var{ascent} is @code{center}, the image is vertically centered
+around a centerline which would be the vertical centerline of text drawn
+at the position of the image, in the manner specified by the text
+properties and overlays that apply to the image.
+
+If this property is omitted, it defaults to 50.
+
+@item :relief @var{relief}
+The @code{:relief} property, if non-@code{nil}, adds a shadow rectangle
+around the image. The value, @var{relief}, specifies the width of the
+shadow lines, in pixels. If @var{relief} is negative, shadows are drawn
+so that the image appears as a pressed button; otherwise, it appears as
+an unpressed button.
+
+@item :conversion @var{algorithm}
+The @code{:conversion} property, if non-@code{nil}, specifies a
+conversion algorithm that should be applied to the image before it is
+displayed; the value, @var{algorithm}, specifies which algorithm.
+
+@table @code
+@item laplace
+@itemx emboss
+Specifies the Laplace edge detection algorithm, which blurs out small
+differences in color while highlighting larger differences. People
+sometimes consider this useful for displaying the image for a
+``disabled'' button.
+
+@item (edge-detection :matrix @var{matrix} :color-adjust @var{adjust})
+Specifies a general edge-detection algorithm. @var{matrix} must be
+either a nine-element list or a nine-element vector of numbers. A pixel
+at position @math{x/y} in the transformed image is computed from
+original pixels around that position. @var{matrix} specifies, for each
+pixel in the neighborhood of @math{x/y}, a factor with which that pixel
+will influence the transformed pixel; element @math{0} specifies the
+factor for the pixel at @math{x-1/y-1}, element @math{1} the factor for
+the pixel at @math{x/y-1} etc., as shown below:
+@iftex
+@tex
+$$\pmatrix{x-1/y-1 & x/y-1 & x+1/y-1 \cr
+ x-1/y & x/y & x+1/y \cr
+ x-1/y+1& x/y+1 & x+1/y+1 \cr}$$
+@end tex
+@end iftex
+@ifnottex
+@display
+ (x-1/y-1 x/y-1 x+1/y-1
+ x-1/y x/y x+1/y
+ x-1/y+1 x/y+1 x+1/y+1)
+@end display
+@end ifnottex
+
+The resulting pixel is computed from the color intensity of the color
+resulting from summing up the RGB values of surrounding pixels,
+multiplied by the specified factors, and dividing that sum by the sum
+of the factors' absolute values.
+
+Laplace edge-detection currently uses a matrix of
+@iftex
+@tex
+$$\pmatrix{1 & 0 & 0 \cr
+ 0& 0 & 0 \cr
+ 9 & 9 & -1 \cr}$$
+@end tex
+@end iftex
+@ifnottex
+@display
+ (1 0 0
+ 0 0 0
+ 9 9 -1)
+@end display
+@end ifnottex
+
+Emboss edge-detection uses a matrix of
+@iftex
+@tex
+$$\pmatrix{ 2 & -1 & 0 \cr
+ -1 & 0 & 1 \cr
+ 0 & 1 & -2 \cr}$$
+@end tex
+@end iftex
+@ifnottex
+@display
+ ( 2 -1 0
+ -1 0 1
+ 0 1 -2)
+@end display
+@end ifnottex
+
+@item disabled
+Specifies transforming the image so that it looks ``disabled''.
+@end table
+
+@item :mask @var{mask}
+If @var{mask} is @code{heuristic} or @code{(heuristic @var{bg})}, build
+a clipping mask for the image, so that the background of a frame is
+visible behind the image. If @var{bg} is not specified, or if @var{bg}
+is @code{t}, determine the background color of the image by looking at
+the four corners of the image, assuming the most frequently occurring
+color from the corners is the background color of the image. Otherwise,
+@var{bg} must be a list @code{(@var{red} @var{green} @var{blue})}
+specifying the color to assume for the background of the image.
+
+If @var{mask} is @code{nil}, remove a mask from the image, if it has
+one. Images in some formats include a mask which can be removed by
+specifying @code{:mask nil}.
+
+@item :pointer @var{shape}
+This specifies the pointer shape when the mouse pointer is over this
+image. @xref{Pointer Shape}, for available pointer shapes.
+
+@item :map @var{map}
+This associates an image map of @dfn{hot spots} with this image.
+
+An image map is an alist where each element has the format
+@code{(@var{area} @var{id} @var{plist})}. An @var{area} is specified
+as either a rectangle, a circle, or a polygon.
+
+A rectangle is a cons
+@code{(rect . ((@var{x0} . @var{y0}) . (@var{x1} . @var{y1})))}
+which specifies the pixel coordinates of the upper left and bottom right
+corners of the rectangle area.
+
+A circle is a cons
+@code{(circle . ((@var{x0} . @var{y0}) . @var{r}))}
+which specifies the center and the radius of the circle; @var{r} may
+be a float or integer.
+
+A polygon is a cons
+@code{(poly . [@var{x0} @var{y0} @var{x1} @var{y1} ...])}
+where each pair in the vector describes one corner in the polygon.
+
+When the mouse pointer is above a hot-spot area of an image, the
+@var{plist} of that hot-spot is consulted; if it contains a @code{help-echo}
+property it defines a tool-tip for the hot-spot, and if it contains
+a @code{pointer} property, it defines the shape of the mouse cursor when
+it is over the hot-spot.
+@xref{Pointer Shape}, for available pointer shapes.
+
+When you click the mouse when the mouse pointer is over a hot-spot, an
+event is composed by combining the @var{id} of the hot-spot with the
+mouse event; for instance, @code{[area4 mouse-1]} if the hot-spot's
+@var{id} is @code{area4}.
+@end table
+
+@defun image-mask-p spec &optional frame
+@tindex image-mask-p
+This function returns @code{t} if image @var{spec} has a mask bitmap.
+@var{frame} is the frame on which the image will be displayed.
+@var{frame} @code{nil} or omitted means to use the selected frame
+(@pxref{Input Focus}).
+@end defun
+
+@node XBM Images
+@subsection XBM Images
+@cindex XBM
+
+ To use XBM format, specify @code{xbm} as the image type. This image
+format doesn't require an external library, so images of this type are
+always supported.
+
+ Additional image properties supported for the @code{xbm} image type are:
-If @var{string} does not reach @var{width}, then the result ends where
-@var{string} ends. If one multi-column character in @var{string}
-extends across the column @var{width}, that character is not included in
-the result. Thus, the result can fall short of @var{width} but cannot
-go beyond it.
+@table @code
+@item :foreground @var{foreground}
+The value, @var{foreground}, should be a string specifying the image
+foreground color, or @code{nil} for the default color. This color is
+used for each pixel in the XBM that is 1. The default is the frame's
+foreground color.
+
+@item :background @var{background}
+The value, @var{background}, should be a string specifying the image
+background color, or @code{nil} for the default color. This color is
+used for each pixel in the XBM that is 0. The default is the frame's
+background color.
+@end table
-The optional argument @var{start-column} specifies the starting column.
-If this is non-@code{nil}, then the first @var{start-column} columns of
-the string are omitted from the value. If one multi-column character in
-@var{string} extends across the column @var{start-column}, that
-character is not included.
+ If you specify an XBM image using data within Emacs instead of an
+external file, use the following three properties:
-The optional argument @var{padding}, if non-@code{nil}, is a padding
-character added at the beginning and end of the result string, to extend
-it to exactly @var{width} columns. The padding character is used at the
-end of the result if it falls short of @var{width}. It is also used at
-the beginning of the result if one multi-column character in
-@var{string} extends across the column @var{start-column}.
+@table @code
+@item :data @var{data}
+The value, @var{data}, specifies the contents of the image.
+There are three formats you can use for @var{data}:
-@example
-(truncate-string-to-width "\tab\t" 12 4)
- @result{} "ab"
-(truncate-string-to-width "\tab\t" 12 4 ?\ )
- @result{} " ab "
-@end example
-@end defun
+@itemize @bullet
+@item
+A vector of strings or bool-vectors, each specifying one line of the
+image. Do specify @code{:height} and @code{:width}.
-@node Faces
-@section Faces
-@cindex face
+@item
+A string containing the same byte sequence as an XBM file would contain.
+You must not specify @code{:height} and @code{:width} in this case,
+because omitting them is what indicates the data has the format of an
+XBM file. The file contents specify the height and width of the image.
-A @dfn{face} is a named collection of graphical attributes: font,
-foreground color, background color, and optional underlining. Faces
-control the display of text on the screen.
+@item
+A string or a bool-vector containing the bits of the image (plus perhaps
+some extra bits at the end that will not be used). It should contain at
+least @var{width} * @code{height} bits. In this case, you must specify
+@code{:height} and @code{:width}, both to indicate that the string
+contains just the bits rather than a whole XBM file, and to specify the
+size of the image.
+@end itemize
-@cindex face id
-Each face has its own @dfn{face id number} which distinguishes faces at
-low levels within Emacs. However, for most purposes, you can refer to
-faces in Lisp programs by their names.
+@item :width @var{width}
+The value, @var{width}, specifies the width of the image, in pixels.
-@defun facep object
-This function returns @code{t} if @var{object} is a face name symbol (or
-if it is a vector of the kind used internally to record face data). It
-returns @code{nil} otherwise.
-@end defun
+@item :height @var{height}
+The value, @var{height}, specifies the height of the image, in pixels.
+@end table
-Each face name is meaningful for all frames, and by default it has the
-same meaning in all frames. But you can arrange to give a particular
-face name a special meaning in one frame if you wish.
+@node XPM Images
+@subsection XPM Images
+@cindex XPM
-@menu
-* Standard Faces:: The faces Emacs normally comes with.
-* Merging Faces:: How Emacs decides which face to use for a character.
-* Face Functions:: How to define and examine faces.
-@end menu
+ To use XPM format, specify @code{xpm} as the image type. The
+additional image property @code{:color-symbols} is also meaningful with
+the @code{xpm} image type:
-@node Standard Faces
-@subsection Standard Faces
+@table @code
+@item :color-symbols @var{symbols}
+The value, @var{symbols}, should be an alist whose elements have the
+form @code{(@var{name} . @var{color})}. In each element, @var{name} is
+the name of a color as it appears in the image file, and @var{color}
+specifies the actual color to use for displaying that name.
+@end table
- This table lists all the standard faces and their uses.
+@node GIF Images
+@subsection GIF Images
+@cindex GIF
+
+ For GIF images, specify image type @code{gif}.
@table @code
-@item default
-@kindex default @r{(face name)}
-This face is used for ordinary text.
+@item :index @var{index}
+You can use @code{:index} to specify one image from a GIF file that
+contains more than one image. This property specifies use of image
+number @var{index} from the file. If the GIF file doesn't contain an
+image with index @var{index}, the image displays as a hollow box.
+@end table
-@item modeline
-@kindex modeline @r{(face name)}
-This face is used for mode lines and menu bars.
+@ignore
+This could be used to implement limited support for animated GIFs.
+For example, the following function displays a multi-image GIF file
+at point-min in the current buffer, switching between sub-images
+every 0.1 seconds.
+
+(defun show-anim (file max)
+ "Display multi-image GIF file FILE which contains MAX subimages."
+ (display-anim (current-buffer) file 0 max t))
+
+(defun display-anim (buffer file idx max first-time)
+ (when (= idx max)
+ (setq idx 0))
+ (let ((img (create-image file nil :image idx)))
+ (save-excursion
+ (set-buffer buffer)
+ (goto-char (point-min))
+ (unless first-time (delete-char 1))
+ (insert-image img))
+ (run-with-timer 0.1 nil 'display-anim buffer file (1+ idx) max nil)))
+@end ignore
+
+@node Postscript Images
+@subsection Postscript Images
+@cindex Postscript images
+
+ To use Postscript for an image, specify image type @code{postscript}.
+This works only if you have Ghostscript installed. You must always use
+these three properties:
-@item region
-@kindex region @r{(face name)}
-This face is used for highlighting the region in Transient Mark mode.
+@table @code
+@item :pt-width @var{width}
+The value, @var{width}, specifies the width of the image measured in
+points (1/72 inch). @var{width} must be an integer.
-@item secondary-selection
-@kindex secondary-selection @r{(face name)}
-This face is used to show any secondary selection you have made.
+@item :pt-height @var{height}
+The value, @var{height}, specifies the height of the image in points
+(1/72 inch). @var{height} must be an integer.
-@item highlight
-@kindex highlight @r{(face name)}
-This face is meant to be used for highlighting for various purposes.
+@item :bounding-box @var{box}
+The value, @var{box}, must be a list or vector of four integers, which
+specifying the bounding box of the Postscript image, analogous to the
+@samp{BoundingBox} comment found in Postscript files.
-@item underline
-@kindex underline @r{(face name)}
-This face underlines text.
+@example
+%%BoundingBox: 22 171 567 738
+@end example
+@end table
-@item bold
-@kindex bold @r{(face name)}
-This face uses a bold font, if possible. It uses the bold variant of
-the frame's font, if it has one. It's up to you to choose a default
-font that has a bold variant, if you want to use one.
+ Displaying Postscript images from Lisp data is not currently
+implemented, but it may be implemented by the time you read this.
+See the @file{etc/NEWS} file to make sure.
-@item italic
-@kindex italic @r{(face name)}
-This face uses the italic variant of the frame's font, if it has one.
+@node Other Image Types
+@subsection Other Image Types
+@cindex PBM
-@item bold-italic
-@kindex bold-italic @r{(face name)}
-This face uses the bold italic variant of the frame's font, if it has
-one.
+ For PBM images, specify image type @code{pbm}. Color, gray-scale and
+monochromatic images are supported. For mono PBM images, two additional
+image properties are supported.
+
+@table @code
+@item :foreground @var{foreground}
+The value, @var{foreground}, should be a string specifying the image
+foreground color, or @code{nil} for the default color. This color is
+used for each pixel in the XBM that is 1. The default is the frame's
+foreground color.
+
+@item :background @var{background}
+The value, @var{background}, should be a string specifying the image
+background color, or @code{nil} for the default color. This color is
+used for each pixel in the XBM that is 0. The default is the frame's
+background color.
@end table
-@node Merging Faces
-@subsection Merging Faces for Display
+ For JPEG images, specify image type @code{jpeg}.
- Here are all the ways to specify which face to use for display of text:
+ For TIFF images, specify image type @code{tiff}.
-@itemize @bullet
-@item
-With defaults. Each frame has a @dfn{default face}, whose id number is
-zero, which is used for all text that doesn't somehow specify another
-face.
+ For PNG images, specify image type @code{png}.
-@item
-With text properties. A character may have a @code{face} property; if so,
-it is displayed with that face. @xref{Special Properties}.
+@node Defining Images
+@subsection Defining Images
-If the character has a @code{mouse-face} property, that is used instead
-of the @code{face} property when the mouse is ``near enough'' to the
-character.
+ The functions @code{create-image}, @code{defimage} and
+@code{find-image} provide convenient ways to create image descriptors.
-@item
-With overlays. An overlay may have @code{face} and @code{mouse-face}
-properties too; they apply to all the text covered by the overlay.
+@defun create-image file-or-data &optional type data-p &rest props
+@tindex create-image
+This function creates and returns an image descriptor which uses the
+data in @var{file-or-data}. @var{file-or-data} can be a file name or
+a string containing the image data; @var{data-p} should be @code{nil}
+for the former case, non-@code{nil} for the latter case.
-@item
-With a region that is active. In Transient Mark mode, the region is
-highlighted with a particular face (see @code{region-face}, below).
+The optional argument @var{type} is a symbol specifying the image type.
+If @var{type} is omitted or @code{nil}, @code{create-image} tries to
+determine the image type from the file's first few bytes, or else
+from the file's name.
-@item
-With special glyphs. Each glyph can specify a particular face id
-number. @xref{Glyphs}.
-@end itemize
+The remaining arguments, @var{props}, specify additional image
+properties---for example,
- If these various sources together specify more than one face for a
-particular character, Emacs merges the attributes of the various faces
-specified. The attributes of the faces of special glyphs come first;
-then comes the face for region highlighting, if appropriate;
-then come attributes of faces from overlays, followed by those from text
-properties, and last the default face.
+@example
+(create-image "foo.xpm" 'xpm nil :heuristic-mask t)
+@end example
- When multiple overlays cover one character, an overlay with higher
-priority overrides those with lower priority. @xref{Overlays}.
+The function returns @code{nil} if images of this type are not
+supported. Otherwise it returns an image descriptor.
+@end defun
- If an attribute such as the font or a color is not specified in any of
-the above ways, the frame's own font or color is used.
+@defmac defimage symbol specs &optional doc
+@tindex defimage
+This macro defines @var{symbol} as an image name. The arguments
+@var{specs} is a list which specifies how to display the image.
+The third argument, @var{doc}, is an optional documentation string.
-@node Face Functions
-@subsection Functions for Working with Faces
+Each argument in @var{specs} has the form of a property list, and each
+one should specify at least the @code{:type} property and either the
+@code{:file} or the @code{:data} property. The value of @code{:type}
+should be a symbol specifying the image type, the value of
+@code{:file} is the file to load the image from, and the value of
+@code{:data} is a string containing the actual image data. Here is an
+example:
- The attributes a face can specify include the font, the foreground
-color, the background color, and underlining. The face can also leave
-these unspecified by giving the value @code{nil} for them.
+@example
+(defimage test-image
+ ((:type xpm :file "~/test1.xpm")
+ (:type xbm :file "~/test1.xbm")))
+@end example
- Here are the primitives for creating and changing faces.
+@code{defimage} tests each argument, one by one, to see if it is
+usable---that is, if the type is supported and the file exists. The
+first usable argument is used to make an image descriptor which is
+stored in @var{symbol}.
+
+If none of the alternatives will work, then @var{symbol} is defined
+as @code{nil}.
+@end defmac
+
+@defun find-image specs
+@tindex find-image
+This function provides a convenient way to find an image satisfying one
+of a list of image specifications @var{specs}.
+
+Each specification in @var{specs} is a property list with contents
+depending on image type. All specifications must at least contain the
+properties @code{:type @var{type}} and either @w{@code{:file @var{file}}}
+or @w{@code{:data @var{DATA}}}, where @var{type} is a symbol specifying
+the image type, e.g.@: @code{xbm}, @var{file} is the file to load the
+image from, and @var{data} is a string containing the actual image data.
+The first specification in the list whose @var{type} is supported, and
+@var{file} exists, is used to construct the image specification to be
+returned. If no specification is satisfied, @code{nil} is returned.
+
+The image is looked for first on @code{load-path} and then in
+@code{data-directory}.
+@end defun
-@defun make-face name
-This function defines a new face named @var{name}, initially with all
-attributes @code{nil}. It does nothing if there is already a face named
-@var{name}.
+@node Showing Images
+@subsection Showing Images
+
+ You can use an image descriptor by setting up the @code{display}
+property yourself, but it is easier to use the functions in this
+section.
+
+@defun insert-image image &optional string area slice
+This function inserts @var{image} in the current buffer at point. The
+value @var{image} should be an image descriptor; it could be a value
+returned by @code{create-image}, or the value of a symbol defined with
+@code{defimage}. The argument @var{string} specifies the text to put
+in the buffer to hold the image. If it is omitted or @code{nil},
+@code{insert-image} uses @code{" "} by default.
+
+The argument @var{area} specifies whether to put the image in a margin.
+If it is @code{left-margin}, the image appears in the left margin;
+@code{right-margin} specifies the right margin. If @var{area} is
+@code{nil} or omitted, the image is displayed at point within the
+buffer's text.
+
+The argument @var{slice} specifies a slice of the image to insert. If
+@var{slice} is @code{nil} or omitted the whole image is inserted.
+Otherwise, @var{slice} is a list @code{(@var{x} @var{y} @var{width}
+@var{height})} which specifies the @var{x} and @var{y} positions and
+@var{width} and @var{height} of the image area to insert. Integer
+values are in units of pixels. A floating point number in the range
+0.0--1.0 stands for that fraction of the width or height of the entire
+image.
+
+Internally, this function inserts @var{string} in the buffer, and gives
+it a @code{display} property which specifies @var{image}. @xref{Display
+Property}.
@end defun
-@defun face-list
-This function returns a list of all defined face names.
+@defun insert-sliced-image image &optional string area rows cols
+This function inserts @var{image} in the current buffer at point, like
+@code{insert-image}, but splits the image into @var{rows}x@var{cols}
+equally sized slices.
@end defun
-@defun copy-face old-face new-name &optional frame new-frame
-This function defines the face @var{new-name} as a copy of the existing
-face named @var{old-face}. It creates the face @var{new-name} if that
-doesn't already exist.
+@defun put-image image pos &optional string area
+This function puts image @var{image} in front of @var{pos} in the
+current buffer. The argument @var{pos} should be an integer or a
+marker. It specifies the buffer position where the image should appear.
+The argument @var{string} specifies the text that should hold the image
+as an alternative to the default.
+
+The argument @var{image} must be an image descriptor, perhaps returned
+by @code{create-image} or stored by @code{defimage}.
+
+The argument @var{area} specifies whether to put the image in a margin.
+If it is @code{left-margin}, the image appears in the left margin;
+@code{right-margin} specifies the right margin. If @var{area} is
+@code{nil} or omitted, the image is displayed at point within the
+buffer's text.
+
+Internally, this function creates an overlay, and gives it a
+@code{before-string} property containing text that has a @code{display}
+property whose value is the image. (Whew!)
+@end defun
-If the optional argument @var{frame} is given, this function applies
-only to that frame. Otherwise it applies to each frame individually,
-copying attributes from @var{old-face} in each frame to @var{new-face}
-in the same frame.
+@defun remove-images start end &optional buffer
+This function removes images in @var{buffer} between positions
+@var{start} and @var{end}. If @var{buffer} is omitted or @code{nil},
+images are removed from the current buffer.
-If the optional argument @var{new-frame} is given, then @code{copy-face}
-copies the attributes of @var{old-face} in @var{frame} to @var{new-name}
-in @var{new-frame}.
+This removes only images that were put into @var{buffer} the way
+@code{put-image} does it, not images that were inserted with
+@code{insert-image} or in other ways.
@end defun
- You can modify the attributes of an existing face with the following
-functions. If you specify @var{frame}, they affect just that frame;
-otherwise, they affect all frames as well as the defaults that apply to
-new frames.
+@defun image-size spec &optional pixels frame
+@tindex image-size
+This function returns the size of an image as a pair
+@w{@code{(@var{width} . @var{height})}}. @var{spec} is an image
+specification. @var{pixels} non-@code{nil} means return sizes
+measured in pixels, otherwise return sizes measured in canonical
+character units (fractions of the width/height of the frame's default
+font). @var{frame} is the frame on which the image will be displayed.
+@var{frame} null or omitted means use the selected frame (@pxref{Input
+Focus}).
+@end defun
-@defun set-face-foreground face color &optional frame
-@defunx set-face-background face color &optional frame
-These functions set the foreground (or background, respectively) color
-of face @var{face} to @var{color}. The argument @var{color} should be a
-string, the name of a color.
+@node Image Cache
+@subsection Image Cache
-Certain shades of gray are implemented by stipple patterns on
-black-and-white screens.
+ Emacs stores images in an image cache when it displays them, so it can
+display them again more efficiently. It removes an image from the cache
+when it hasn't been displayed for a specified period of time.
+
+When an image is looked up in the cache, its specification is compared
+with cached image specifications using @code{equal}. This means that
+all images with equal specifications share the same image in the cache.
+
+@defvar image-cache-eviction-delay
+@tindex image-cache-eviction-delay
+This variable specifies the number of seconds an image can remain in the
+cache without being displayed. When an image is not displayed for this
+length of time, Emacs removes it from the image cache.
+
+If the value is @code{nil}, Emacs does not remove images from the cache
+except when you explicitly clear it. This mode can be useful for
+debugging.
+@end defvar
+
+@defun clear-image-cache &optional frame
+@tindex clear-image-cache
+This function clears the image cache. If @var{frame} is non-@code{nil},
+only the cache for that frame is cleared. Otherwise all frames' caches
+are cleared.
@end defun
-@defun set-face-stipple face pattern &optional frame
-This function sets the background stipple pattern of face @var{face} to
-@var{pattern}. The argument @var{pattern} should be the name of a
-stipple pattern defined by the X server, or @code{nil} meaning don't use
-stipple.
+@node Buttons
+@section Buttons
+@cindex buttons
+@cindex buttons in buffers
+@cindex clickable buttons in buffers
+
+ The @emph{button} package defines functions for inserting and
+manipulating clickable (with the mouse, or via keyboard commands)
+buttons in Emacs buffers, such as might be used for help hyper-links,
+etc. Emacs uses buttons for the hyper-links in help text and the like.
+
+ A button is essentially a set of properties attached (via text
+properties or overlays) to a region of text in an Emacs buffer. These
+properties are called @dfn{button properties}.
+
+ One of the these properties (@code{action}) is a function, which will
+be called when the user invokes it using the keyboard or the mouse.
+The invoked function may then examine the button and use its other
+properties as desired.
+
+ In some ways the Emacs button package duplicates functionality offered
+by the widget package (@pxref{Top, , Introduction, widget, The Emacs
+Widget Library}), but the button package has the advantage that it is
+much faster, much smaller, and much simpler to use (for elisp
+programmers---for users, the result is about the same). The extra
+speed and space savings are useful mainly if you need to create many
+buttons in a buffer (for instance an @code{*Apropos*} buffer uses
+buttons to make entries clickable, and may contain many thousands of
+entries).
-Normally there is no need to pay attention to stipple patterns, because
-they are used automatically to handle certain shades of gray.
+@menu
+* Button Properties:: Button properties with special meanings.
+* Button Types:: Defining common properties for classes of buttons.
+* Making Buttons:: Adding buttons to Emacs buffers.
+* Manipulating Buttons:: Getting and setting properties of buttons.
+* Button Buffer Commands:: Buffer-wide commands and bindings for buttons.
+@end menu
+
+@node Button Properties
+@subsection Button Properties
+@cindex button properties
+
+ Buttons have an associated list of properties defining their
+appearance and behavior, and other arbitrary properties may be used
+for application specific purposes. Some properties that have special
+meaning to the button package include:
+
+@table @code
+@item action
+@kindex action @r{(button property)}
+The function to call when the user invokes the button, which is passed
+the single argument @var{button}. By default this is @code{ignore},
+which does nothing.
+
+@item mouse-action
+@kindex mouse-action @r{(button property)}
+This is similar to @code{action}, and when present, will be used
+instead of @code{action} for button invocations resulting from
+mouse-clicks (instead of the user hitting @key{RET}). If not
+present, mouse-clicks use @code{action} instead.
+
+@item face
+@kindex face @r{(button property)}
+This is an Emacs face controlling how buttons of this type are
+displayed; by default this is the @code{button} face.
+
+@item mouse-face
+@kindex mouse-face @r{(button property)}
+This is an additional face which controls appearance during
+mouse-overs (merged with the usual button face); by default this is
+the usual Emacs @code{highlight} face.
+
+@item keymap
+@kindex keymap @r{(button property)}
+The button's keymap, defining bindings active within the button
+region. By default this is the usual button region keymap, stored
+in the variable @code{button-map}, which defines @key{RET} and
+@key{mouse-2} to invoke the button.
+
+@item type
+@kindex type @r{(button property)}
+The button-type of the button. When creating a button, this is
+usually specified using the @code{:type} keyword argument.
+@xref{Button Types}.
+
+@item help-echo
+@kindex help-index @r{(button property)}
+A string displayed by the Emacs tool-tip help system; by default,
+@code{"mouse-2, RET: Push this button"}.
+
+@item follow-link
+@kindex follow-link @r{(button property)}
+The follow-link property, defining how a @key{Mouse-1} click behaves
+on this button, @xref{Links and Mouse-1}.
+
+@item button
+@kindex button @r{(button property)}
+All buttons have a non-@code{nil} @code{button} property, which may be useful
+in finding regions of text that comprise buttons (which is what the
+standard button functions do).
+@end table
+
+ There are other properties defined for the regions of text in a
+button, but these are not generally interesting for typical uses.
+
+@node Button Types
+@subsection Button Types
+@cindex button types
+
+ Every button has a button @emph{type}, which defines default values
+for the button's properties. Button types are arranged in a
+hierarchy, with specialized types inheriting from more general types,
+so that it's easy to define special-purpose types of buttons for
+specific tasks.
+
+@defun define-button-type name &rest properties
+@tindex define-button-type
+Define a `button type' called @var{name}. The remaining arguments
+form a sequence of @var{property value} pairs, specifying default
+property values for buttons with this type (a button's type may be set
+by giving it a @code{type} property when creating the button, using
+the @code{:type} keyword argument).
+
+In addition, the keyword argument @code{:supertype} may be used to
+specify a button-type from which @var{name} inherits its default
+property values. Note that this inheritance happens only when
+@var{name} is defined; subsequent changes to a supertype are not
+reflected in its subtypes.
@end defun
-@defun set-face-font face font &optional frame
-This function sets the font of face @var{face}. The argument @var{font}
-should be a string. Note that if you set the font explicitly, the bold
-and italic attributes cease to have any effect, because the precise font
-that you specified is always used.
+ Using @code{define-button-type} to define default properties for
+buttons is not necessary---buttons without any specified type use the
+built-in button-type @code{button}---but it is encouraged, since
+doing so usually makes the resulting code clearer and more efficient.
+
+@node Making Buttons
+@subsection Making Buttons
+@cindex making buttons
+
+ Buttons are associated with a region of text, using an overlay or
+text properties to hold button-specific information, all of which are
+initialized from the button's type (which defaults to the built-in
+button type @code{button}). Like all Emacs text, the appearance of
+the button is governed by the @code{face} property; by default (via
+the @code{face} property inherited from the @code{button} button-type)
+this is a simple underline, like a typical web-page link.
+
+ For convenience, there are two sorts of button-creation functions,
+those that add button properties to an existing region of a buffer,
+called @code{make-...button}, and those also insert the button text,
+called @code{insert-...button}.
+
+ The button-creation functions all take the @code{&rest} argument
+@var{properties}, which should be a sequence of @var{property value}
+pairs, specifying properties to add to the button; see @ref{Button
+Properties}. In addition, the keyword argument @code{:type} may be
+used to specify a button-type from which to inherit other properties;
+see @ref{Button Types}. Any properties not explicitly specified
+during creation will be inherited from the button's type (if the type
+defines such a property).
+
+ The following functions add a button using an overlay
+(@pxref{Overlays}) to hold the button properties:
+
+@defun make-button beg end &rest properties
+@tindex make-button
+This makes a button from @var{beg} to @var{end} in the
+current buffer, and returns it.
@end defun
-@defun set-face-underline-p face underline-p &optional frame
-This function sets the underline attribute of face @var{face}.
-Non-@code{nil} means do underline; @code{nil} means don't.
+@defun insert-button label &rest properties
+@tindex insert-button
+This insert a button with the label @var{label} at point,
+and returns it.
@end defun
-@tindex set-face-bold-p
-@defun set-face-bold-p face bold-p &optional frame
-This function sets the bold attribute of face @var{face}.
-Non-@code{nil} means bold; @code{nil} means non-bold.
+ The following functions are similar, but use Emacs text properties
+(@pxref{Text Properties}) to hold the button properties, making the
+button actually part of the text instead of being a property of the
+buffer. Buttons using text properties do not create markers into the
+buffer, which is important for speed when you use extremely large
+numbers of buttons. Both functions return the position of the start
+of the new button:
+
+@defun make-text-button beg end &rest properties
+@tindex make-text-button
+This makes a button from @var{beg} to @var{end} in the current buffer, using
+text properties.
@end defun
-@tindex set-face-italic-p
-@defun set-face-italic-p face italic-p &optional frame
-This function sets the italic attribute of face @var{face}.
-Non-@code{nil} means italic; @code{nil} means non-italic.
+@defun insert-text-button label &rest properties
+@tindex insert-text-button
+This inserts a button with the label @var{label} at point, using text
+properties.
@end defun
-@defun invert-face face &optional frame
-Swap the foreground and background colors of face @var{face}. If the
-face doesn't specify both foreground and background, then its foreground
-and background are set to the default background and foreground,
-respectively.
+@node Manipulating Buttons
+@subsection Manipulating Buttons
+@cindex manipulating buttons
+
+These are functions for getting and setting properties of buttons.
+Often these are used by a button's invocation function to determine
+what to do.
+
+Where a @var{button} parameter is specified, it means an object
+referring to a specific button, either an overlay (for overlay
+buttons), or a buffer-position or marker (for text property buttons).
+Such an object is passed as the first argument to a button's
+invocation function when it is invoked.
+
+@defun button-start button
+@tindex button-start
+Return the position at which @var{button} starts.
@end defun
- These functions examine the attributes of a face. If you don't
-specify @var{frame}, they refer to the default data for new frames.
+@defun button-end button
+@tindex button-end
+Return the position at which @var{button} ends.
+@end defun
-@defun face-foreground face &optional frame
-@defunx face-background face &optional frame
-These functions return the foreground color (or background color,
-respectively) of face @var{face}, as a string.
+@defun button-get button prop
+@tindex button-get
+Get the property of button @var{button} named @var{prop}.
@end defun
-@defun face-stipple face &optional frame
-This function returns the name of the background stipple pattern of face
-@var{face}, or @code{nil} if it doesn't have one.
+@defun button-put button prop val
+@tindex button-put
+Set @var{button}'s @var{prop} property to @var{val}.
@end defun
-@defun face-font face &optional frame
-This function returns the name of the font of face @var{face}.
+@defun button-activate button &optional use-mouse-action
+@tindex button-activate
+Call @var{button}'s @code{action} property (i.e., invoke it). If
+@var{use-mouse-action} is non-@code{nil}, try to invoke the button's
+@code{mouse-action} property instead of @code{action}; if the button
+has no @code{mouse-action} property, use @code{action} as normal.
@end defun
-@defun face-underline-p face &optional frame
-This function returns the underline attribute of face @var{face}.
+@defun button-label button
+@tindex button-label
+Return @var{button}'s text label.
@end defun
-@tindex face-bold-p
-@defun face-bold-p face &optional frame
-This function returns the bold attribute of face @var{face}.
+@defun button-type button
+@tindex button-type
+Return @var{button}'s button-type.
@end defun
-@tindex face-italic-p
-@defun face-italic-p face &optional frame
-This function returns the italic attribute of face @var{face}.
+@defun button-has-type-p button type
+@tindex button-has-type-p
+Return @code{t} if @var{button} has button-type @var{type}, or one of
+@var{type}'s subtypes.
@end defun
-@defun face-id face
-This function returns the face id number of face @var{face}.
+@defun button-at pos
+@tindex button-at
+Return the button at position @var{pos} in the current buffer, or @code{nil}.
@end defun
-@tindex face-documentation
-@defun face-documentation face
-This function returns the documentation string of face @var{face}, or
-@code{nil} if none was specified for it.
+@defun button-type-put type prop val
+@tindex button-type-put
+Set the button-type @var{type}'s @var{prop} property to @var{val}.
@end defun
-@defun face-equal face1 face2 &optional frame
-This returns @code{t} if the faces @var{face1} and @var{face2} have the
-same attributes for display.
+@defun button-type-get type prop
+@tindex button-type-get
+Get the property of button-type @var{type} named @var{prop}.
@end defun
-@defun face-differs-from-default-p face &optional frame
-This returns @code{t} if the face @var{face} displays differently from
-the default face. A face is considered to be ``the same'' as the normal
-face if each attribute is either the same as that of the default face or
-@code{nil} (meaning to inherit from the default).
+@defun button-type-subtype-p type supertype
+@tindex button-type-subtype-p
+Return @code{t} if button-type @var{type} is a subtype of @var{supertype}.
@end defun
-@defvar region-face
-This variable's value specifies the face id to use to display characters
-in the region when it is active (in Transient Mark mode only). The face
-thus specified takes precedence over all faces that come from text
-properties and overlays, for characters in the region. @xref{The Mark},
-for more information about Transient Mark mode.
+@node Button Buffer Commands
+@subsection Button Buffer Commands
+@cindex button buffer commands
+
+These are commands and functions for locating and operating on
+buttons in an Emacs buffer.
+
+@code{push-button} is the command that a user uses to actually `push'
+a button, and is bound by default in the button itself to @key{RET}
+and to @key{mouse-2} using a region-specific keymap. Commands
+that are useful outside the buttons itself, such as
+@code{forward-button} and @code{backward-button} are additionally
+available in the keymap stored in @code{button-buffer-map}; a mode
+which uses buttons may want to use @code{button-buffer-map} as a
+parent keymap for its keymap.
+
+If the button has a non-@code{nil} @code{follow-link} property, and
+@var{mouse-1-click-follows-link} is set, a quick @key{Mouse-1} click
+will also activate the @code{push-button} command.
+@xref{Links and Mouse-1}.
+
+@deffn Command push-button &optional pos use-mouse-action
+@tindex push-button
+Perform the action specified by a button at location @var{pos}.
+@var{pos} may be either a buffer position or a mouse-event. If
+@var{use-mouse-action} is non-@code{nil}, or @var{pos} is a
+mouse-event (@pxref{Mouse Events}), try to invoke the button's
+@code{mouse-action} property instead of @code{action}; if the button
+has no @code{mouse-action} property, use @code{action} as normal.
+@var{pos} defaults to point, except when @code{push-button} is invoked
+interactively as the result of a mouse-event, in which case, the mouse
+event's position is used. If there's no button at @var{pos}, do
+nothing and return @code{nil}, otherwise return @code{t}.
+@end deffn
-Normally, the value is the id number of the face named @code{region}.
-@end defvar
+@deffn Command forward-button n &optional wrap display-message
+@tindex forward-button
+Move to the @var{n}th next button, or @var{n}th previous button if
+@var{n} is negative. If @var{n} is zero, move to the start of any
+button at point. If @var{wrap} is non-@code{nil}, moving past either
+end of the buffer continues from the other end. If
+@var{display-message} is non-@code{nil}, the button's help-echo string
+is displayed. Any button with a non-@code{nil} @code{skip} property
+is skipped over. Returns the button found.
+@end deffn
+
+@deffn Command backward-button n &optional wrap display-message
+@tindex backward-button
+Move to the @var{n}th previous button, or @var{n}th next button if
+@var{n} is negative. If @var{n} is zero, move to the start of any
+button at point. If @var{wrap} is non-@code{nil}, moving past either
+end of the buffer continues from the other end. If
+@var{display-message} is non-@code{nil}, the button's help-echo string
+is displayed. Any button with a non-@code{nil} @code{skip} property
+is skipped over. Returns the button found.
+@end deffn
+
+@defun next-button pos &optional count-current
+@tindex next-button
+Return the next button after position @var{pos} in the current buffer.
+If @var{count-current} is non-@code{nil}, count any button at
+@var{pos} in the search, instead of starting at the next button.
+@end defun
+
+@defun previous-button pos &optional count-current
+@tindex previous-button
+Return the @var{n}th button before position @var{pos} in the current
+buffer. If @var{count-current} is non-@code{nil}, count any button at
+@var{pos} in the search, instead of starting at the next button.
+@end defun
@node Blinking
@section Blinking Parentheses
This section describes the mechanism by which Emacs shows a matching
open parenthesis when the user inserts a close parenthesis.
-@vindex blink-paren-hook
@defvar blink-paren-function
The value of this variable should be a function (of no arguments) to
be called whenever a character with close parenthesis syntax is inserted.
The value of @code{blink-paren-function} may be @code{nil}, in which
case nothing is done.
-
-@quotation
-@strong{Please note:} This variable was named @code{blink-paren-hook} in
-older Emacs versions, but since it is not called with the standard
-convention for hooks, it was renamed to @code{blink-paren-function} in
-version 19.
-@end quotation
@end defvar
-@defvar blink-matching-paren
+@defopt blink-matching-paren
If this variable is @code{nil}, then @code{blink-matching-open} does
nothing.
-@end defvar
+@end defopt
-@defvar blink-matching-paren-distance
+@defopt blink-matching-paren-distance
This variable specifies the maximum distance to scan for a matching
parenthesis before giving up.
-@end defvar
+@end defopt
-@defvar blink-matching-paren-delay
+@defopt blink-matching-delay
This variable specifies the number of seconds for the cursor to remain
at the matching parenthesis. A fraction of a second often gives
good results, but the default is 1, which works on all systems.
-@end defvar
+@end defopt
-@defun blink-matching-open
+@deffn Command blink-matching-open
This function is the default value of @code{blink-paren-function}. It
assumes that point follows a character with close parenthesis syntax and
moves the cursor momentarily to the matching opening character. If that
(blink-matching-open)))
@end group
@end smallexample
-@end defun
+@end deffn
@node Inverse Video
@section Inverse Video
default is @code{nil}.
@end defopt
-@defopt mode-line-inverse-video
-This variable controls the use of inverse video for mode lines. If it
-is non-@code{nil}, then mode lines are displayed in inverse video.
-Otherwise, mode lines are displayed normally, just like text. The
-default is @code{t}.
-
-For X window frames, this displays mode lines using the face named
-@code{modeline}, which is normally the inverse of the default face
-unless you change it.
-@end defopt
-
@node Usual Display
@section Usual Display Conventions
All other codes in the range 0 through 31, and code 127, display in one
of two ways according to the value of @code{ctl-arrow}. If it is
non-@code{nil}, these codes map to sequences of two glyphs, where the
-first glyph is the @sc{ASCII} code for @samp{^}. (A display table can
+first glyph is the @acronym{ASCII} code for @samp{^}. (A display table can
specify a glyph to use instead of @samp{^}.) Otherwise, these codes map
just like the codes in the range 128 to 255.
+On MS-DOS terminals, Emacs arranges by default for the character code
+127 to be mapped to the glyph code 127, which normally displays as an
+empty polygon. This glyph is used to display non-@acronym{ASCII} characters
+that the MS-DOS terminal doesn't support. @xref{MS-DOS and MULE,,,
+emacs, The GNU Emacs Manual}.
+
@item
Character codes 128 through 255 map to sequences of four glyphs, where
-the first glyph is the @sc{ASCII} code for @samp{\}, and the others are
-digit characters representing the code in octal. (A display table can
-specify a glyph to use instead of @samp{\}.)
+the first glyph is the @acronym{ASCII} code for @samp{\}, and the others are
+digit characters representing the character code in octal. (A display
+table can specify a glyph to use instead of @samp{\}.)
+
+@item
+Multibyte character codes above 256 are displayed as themselves, or as a
+question mark or empty box if the terminal cannot display that
+character.
@end itemize
The usual display conventions apply even when there is a display
table, for any character whose entry in the active display table is
@code{nil}. Thus, when you set up a display table, you need only
-specify the characters for which you want unusual behavior.
+specify the characters for which you want special behavior.
+
+ These display rules apply to carriage return (character code 13), when
+it appears in the buffer. But that character may not appear in the
+buffer where you expect it, if it was eliminated as part of end-of-line
+conversion (@pxref{Coding System Basics}).
These variables affect the way certain characters are displayed on the
screen. Since they change the number of columns the characters occupy,
@defopt tab-width
The value of this variable is the spacing between tab stops used for
-displaying tab characters in Emacs buffers. The default is 8. Note
-that this feature is completely independent of the user-settable tab
-stops used by the command @code{tab-to-tab-stop}. @xref{Indent Tabs}.
+displaying tab characters in Emacs buffers. The value is in units of
+columns, and the default is 8. Note that this feature is completely
+independent of the user-settable tab stops used by the command
+@code{tab-to-tab-stop}. @xref{Indent Tabs}.
@end defopt
+@defopt indicate-empty-lines
+@tindex indicate-empty-lines
+@cindex fringes, and empty line indication
+When this is non-@code{nil}, Emacs displays a special glyph in the
+fringe of each empty line at the end of the buffer, on terminals that
+support it (window systems). @xref{Fringes}.
+@end defopt
+
+@defvar indicate-buffer-boundaries
+This buffer-local variable controls how the buffer boundaries and
+window scrolling are indicated in the window fringes.
+
+Emacs can indicate the buffer boundaries---that is, the first and last
+line in the buffer---with angle icons when they appear on the screen.
+In addition, Emacs can display an up-arrow in the fringe to show
+that there is text above the screen, and a down-arrow to show
+there is text below the screen.
+
+There are four kinds of basic values:
+
+@table @asis
+@item @code{nil}
+Don't display the icons.
+@item @code{left}
+Display them in the left fringe.
+@item @code{right}
+Display them in the right fringe.
+@item @var{anything-else}
+Display the icon at the top of the window top in the left fringe, and other
+in the right fringe.
+@end table
+
+If value is a cons @code{(@var{angles} . @var{arrows})}, @var{angles}
+controls the angle icons, and @var{arrows} controls the arrows. Both
+@var{angles} and @var{arrows} work according to the table above.
+Thus, @code{(t . right)} places the top angle icon in the left
+fringe, the bottom angle icon in the right fringe, and both arrows in
+the right fringe.
+@end defvar
+
+@defvar default-indicate-buffer-boundaries
+The value of this variable is the default value for
+@code{indicate-buffer-boundaries} in buffers that do not override it.
+@end defvar
+
@node Display Tables
@section Display Tables
@cindex display table
-You can use the @dfn{display table} feature to control how all 256
-possible character codes display on the screen. This is useful for
-displaying European languages that have letters not in the @sc{ASCII}
-character set.
+You can use the @dfn{display table} feature to control how all possible
+character codes display on the screen. This is useful for displaying
+European languages that have letters not in the @acronym{ASCII} character
+set.
The display table maps each character code into a sequence of
-@dfn{glyphs}, each glyph being an image that takes up one character
+@dfn{glyphs}, each glyph being a graphic that takes up one character
position on the screen. You can also define how to display each glyph
on your terminal, using the @dfn{glyph table}.
@code{force-mode-line-update} (@pxref{Mode Line Format}).
@menu
-* Display Table Format:: What a display table consists of.
-* Active Display Table:: How Emacs selects a display table to use.
-* Glyphs:: How to define a glyph, and what glyphs mean.
+* Display Table Format:: What a display table consists of.
+* Active Display Table:: How Emacs selects a display table to use.
+* Glyphs:: How to define a glyph, and what glyphs mean.
@end menu
@node Display Table Format
@subsection Display Table Format
- A display table is actually char-table with subtype @code{display-table}.
+ A display table is actually a char-table (@pxref{Char-Tables}) with
+@code{display-table} as its subtype.
@defun make-display-table
This creates and returns a display table. The table initially has
characters, the whole buffer will be displayed as one long ``line.''
The display table also has six ``extra slots'' which serve special
-purposes. Here is a table of their meanings; @code{nil} means to use
-the default stated below.
+purposes. Here is a table of their meanings; @code{nil} in any slot
+means to use the default for that slot, as stated below.
@table @asis
@item 0
The glyph for the end of a truncated screen line (the default for this
-is @samp{$}). @xref{Glyphs}.
+is @samp{$}). @xref{Glyphs}. On graphical terminals, Emacs uses
+arrows in the fringes to indicate truncation, so the display table has
+no effect.
+
@item 1
The glyph for the end of a continued line (the default is @samp{\}).
+On graphical terminals, Emacs uses curved arrows in the fringes to
+indicate continuation, so the display table has no effect.
+
@item 2
The glyph for indicating a character displayed as an octal character
code (the default is @samp{\}).
+
@item 3
The glyph for indicating a control character (the default is @samp{^}).
+
@item 4
A vector of glyphs for indicating the presence of invisible lines (the
default is @samp{...}). @xref{Selective Display}.
+
@item 5
The glyph used to draw the border between side-by-side windows (the
-default is @samp{|}). @xref{Splitting Windows}.
+default is @samp{|}). @xref{Splitting Windows}. This takes effect only
+when there are no scroll bars; if scroll bars are supported and in use,
+a scroll bar separates the two windows.
@end table
For example, here is how to construct a display table that mimics the
(aset disptab 127 (vector ?^ ??)))
@end example
-@tindex display-table-slot
@defun display-table-slot display-table slot
This function returns the value of the extra slot @var{slot} of
@var{display-table}. The argument @var{slot} may be a number from 0 to
@code{selective-display}, and @code{vertical-border}.
@end defun
-@tindex set-display-table-slot
@defun set-display-table-slot display-table slot value
This function stores @var{value} in the extra slot @var{slot} of
@var{display-table}. The argument @var{slot} may be a number from 0 to
@code{selective-display}, and @code{vertical-border}.
@end defun
+@defun describe-display-table display-table
+@tindex describe-display-table
+This function displays a description of the display table
+@var{display-table} in a help buffer.
+@end defun
+
+@deffn Command describe-current-display-table
+@tindex describe-current-display-table
+This command displays a description of the current display table in a
+help buffer.
+@end deffn
+
@node Active Display Table
@subsection Active Display Table
@cindex active display table
table if any. The display table chosen is called the @dfn{active}
display table.
-@defun window-display-table window
+@defun window-display-table &optional window
This function returns @var{window}'s display table, or @code{nil}
-if @var{window} does not have an assigned display table.
+if @var{window} does not have an assigned display table. The default
+for @var{window} is the selected window.
@end defun
@defun set-window-display-table window table
@end defun
@defvar buffer-display-table
-This variable is automatically local in all buffers; its value in a
-particular buffer is the display table for that buffer, or @code{nil} if
-the buffer does not have an assigned display table.
+This variable is automatically buffer-local in all buffers; its value in
+a particular buffer specifies the display table for that buffer. If it
+is @code{nil}, that means the buffer does not have an assigned display
+table.
@end defvar
@defvar standard-display-table
display conventions for all character codes in that window. @xref{Usual
Display}.
+A number of functions for changing the standard display table
+are defined in the library @file{disp-table}.
+
@node Glyphs
@subsection Glyphs
@cindex glyph
A @dfn{glyph} is a generalization of a character; it stands for an
image that takes up a single character position on the screen. Glyphs
-are represented in Lisp as integers, just as characters are.
+are represented in Lisp as integers, just as characters are. Normally
+Emacs finds glyphs in the display table (@pxref{Display Tables}).
+
+ A glyph can be @dfn{simple} or it can be defined by the @dfn{glyph
+table}. A simple glyph is just a way of specifying a character and a
+face to output it in. The glyph code for a simple glyph, mod 524288,
+is the character to output, and the glyph code divided by 524288
+specifies the face number (@pxref{Face Functions}) to use while
+outputting it. (524288 is
+@ifnottex
+2**19.)
+@end ifnottex
+@tex
+$2^{19}$.)
+@end tex
+@xref{Faces}.
-@cindex glyph table
- The meaning of each integer, as a glyph, is defined by the glyph
-table, which is the value of the variable @code{glyph-table}.
+ On character terminals, you can set up a @dfn{glyph table} to define
+the meaning of glyph codes. The glyph codes is the value of the
+variable @code{glyph-table}.
@defvar glyph-table
The value of this variable is the current glyph table. It should be a
-vector; the @var{g}th element defines glyph code @var{g}. If the value
-is @code{nil} instead of a vector, then all glyphs are simple (see
-below).
+vector; the @var{g}th element defines glyph code @var{g}.
+
+If a glyph code is greater than or equal to the length of the glyph
+table, that code is automatically simple. If the value of
+@code{glyph-table} is @code{nil} instead of a vector, then all glyphs
+are simple. The glyph table is not used on graphical displays, only
+on character terminals. On graphical displays, all glyphs are simple.
@end defvar
Here are the possible types of elements in the glyph table:
-@table @var
-@item string
+@table @asis
+@item @var{string}
Send the characters in @var{string} to the terminal to output
this glyph. This alternative is available on character terminals,
-but not under X.
+but not under a window system.
-@item integer
-Define this glyph code as an alias for code @var{integer}. You can use
-an alias to specify a face code for the glyph; see below.
+@item @var{integer}
+Define this glyph code as an alias for glyph code @var{integer}. You
+can use an alias to specify a face code for the glyph and use a small
+number as its code.
@item @code{nil}
-This glyph is simple. On an ordinary terminal, the glyph code mod 524288
-is the character to output. With X, the glyph code mod 524288 is the
-character to output, and the glyph code divided by 524288 specifies the
-@dfn{face id number} to use while outputting it. (524288 is
-@ifinfo
-2**19.
-@end ifinfo
-@tex
-$2^{19}$.
-@end tex
-@xref{Faces}.
+This glyph is simple.
@end table
- If a glyph code is greater than or equal to the length of the glyph
-table, that code is automatically simple.
+@defun create-glyph string
+@tindex create-glyph
+This function returns a newly-allocated glyph code which is set up to
+display by sending @var{string} to the terminal.
+@end defun
@node Beeping
@section Beeping
careful not to use just beeping when signaling an error is more
appropriate. (@xref{Errors}.)
-@defun ding &optional dont-terminate
+@defun ding &optional do-not-terminate
@cindex keyboard macro termination
This function beeps, or flashes the screen (see @code{visible-bell} below).
It also terminates any keyboard macro currently executing unless
-@var{dont-terminate} is non-@code{nil}.
+@var{do-not-terminate} is non-@code{nil}.
@end defun
-@defun beep &optional dont-terminate
+@defun beep &optional do-not-terminate
This is a synonym for @code{ding}.
@end defun
-@defvar visible-bell
+@defopt visible-bell
This variable determines whether Emacs should flash the screen to
represent a bell. Non-@code{nil} means yes, @code{nil} means no. This
-is effective under X windows, and on a character-only terminal provided
-the terminal's Termcap entry defines the visible bell capability
-(@samp{vb}).
-@end defvar
+is effective on a window system, and on a character-only terminal
+provided the terminal's Termcap entry defines the visible bell
+capability (@samp{vb}).
+@end defopt
-@tindex ring-bell-function
@defvar ring-bell-function
If this is non-@code{nil}, it specifies how Emacs should ``ring the
-bell.'' Its value should bea function of no arguments.
+bell.'' Its value should be a function of no arguments. If this is
+non-@code{nil}, it takes precedence over the @code{visible-bell}
+variable.
@end defvar
@node Window Systems
concerned; the individual Emacs windows are not known to X at all.
@defvar window-system
-@cindex X Window System
This variable tells Lisp programs what window system Emacs is running
-under. Its value should be a symbol such as @code{x} (if Emacs is
-running under X) or @code{nil} (if Emacs is running on an ordinary
-terminal).
+under. The possible values are
+
+@table @code
+@item x
+@cindex X Window System
+Emacs is displaying using X.
+@item pc
+Emacs is displaying using MS-DOS.
+@item w32
+Emacs is displaying using Windows.
+@item mac
+Emacs is displaying using a Macintosh.
+@item nil
+Emacs is using a character-based terminal.
+@end table
@end defvar
@defvar window-setup-hook
This variable is a normal hook which Emacs runs after handling the
initialization files. Emacs runs this hook after it has completed
-loading your @file{.emacs} file, the default initialization file (if
-any), and the terminal-specific Lisp code, and runring the hook
+loading your init file, the default initialization file (if
+any), and the terminal-specific Lisp code, and running the hook
@code{term-setup-hook}.
This hook is used for internal purposes: setting up communication with
the window system, and creating the initial window. Users should not
interfere with it.
@end defvar
+
+@ignore
+ arch-tag: ffdf5714-7ecf-415b-9023-fbc6b409c2c6
+@end ignore