* Truncation:: Folding or wrapping long text lines.
* The Echo Area:: Where messages are displayed.
* Warnings:: Displaying warning messages for the user.
+* Progress:: Informing user about progress of a long operation.
* 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 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.
+* Fringe Bitmaps:: Displaying bitmaps in the window fringes.
+* Customizing Bitmaps:: Specifying your own bitmaps to use in the 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.
that warning is not logged.
@end defopt
+@node Progress
+@section 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:
+
+@example
+(let ((progress-reporter
+ (make-progress-reporter "Collecting some mana for Emacs..."
+ 0 500)))
+ (dotimes (k 500)
+ (sit-for 0.01)
+ (progress-reporter-update progress-reporter k))
+ (progress-reporter-done progress-reporter))
+@end example
+
+@defun make-progress-reporter message min-value max-value &optional current-value min-change min-time
+This function creates a progress reporter---the 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.
+
+The @var{message} will be displayed 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 print the message of @var{reporter} followed by
+progress percentage determined by @var{value}. If percentage is zero,
+then it is not printed at all.
+
+@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
+
+@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
+
@node Invisible Text
@section Invisible Text
@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}
@item evaporate
@kindex evaporate @r{(overlay property)}
If this property is non-@code{nil}, the overlay is deleted automatically
-if it becomes empty (i.e., if its length becomes zero). However,
-if the overlay is @emph{already} empty, @code{evaporate} does not
-delete it.
+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 (and overlays)
@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 heigh 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 (@code{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} propery, 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
* 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.
-* Merging Faces:: How Emacs combines the faces specified for a character.
+* 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.
@item fringe
@kindex fringe @r{(face name)}
-This face controls the colors of window fringes, the thin areas on
+This face controls the default colors of window fringes, the thin areas on
either side that are used to display continuation and truncation glyphs.
@item minibuffer-prompt
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{Merging Faces}.
+are merged to specify how to display the text. @xref{Displaying Faces}.
In Emacs 21, any attribute in a face can have the value
@code{unspecified}. This means the face doesn't specify that attribute.
the terminal supports the feature.
@item :foreground
-Foreground color, a string.
+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.
+Background color, a string, like the foreground color.
@item :inverse-video
Whether or not characters should be displayed in inverse video. The
This function returns the @code{:inverse-video} attribute of face @var{face}.
@end defun
-@node Merging Faces
-@subsection Merging Faces for Display
+@node Displaying Faces
+@subsection Displaying Faces
Here are the ways to specify which faces to use for display of text:
@defvar fringes-outside-margins
If the value is non-@code{nil}, the frames appear outside
-the display margins.
+the display margins.
@end defvar
@defvar left-fringe-width
@var{right-width} @var{frames-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
+@section 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.
+
+ These are the 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
+@section 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.
+
+The face you use here should be derived from @code{fringe}, and should
+specify only the foreground color.
+@end defun
+
@node Scroll Bars
@section Scroll Bars
@code{scroll-bar-width} specifies how wide they are (@code{nil}
meaning the default). @xref{Window Frame Parameters}.
-You can also control this for individual windows. Call the function
+@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
-Set width and type of scroll bars of window @var{window}.
-If @var{window} is @code{nil}, the selected window is used.
+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 whatever is specified for width 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.
+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.
+implemented, it has no effect. If @var{window} is @code{nil}, the
+selected window is used.
@end defun
@defun window-scroll-bars &optional window
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
+
+@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
@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.
@table @code
@item :width @var{width}
-Specifies that the space width should be @var{width} times the normal
-character width. @var{width} can be an integer or floating point
-number.
+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
character, multiplied by @var{factor}.
@item :align-to @var{hpos}
-Specifies that the space should be wide enough to reach @var{hpos}. The
-value @var{hpos} is measured in units of the normal character width. It
-may be an integer or a floating point number.
+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 other properties:
+also specify the height of the space, with these properties:
@table @code
@item :height @var{height}
-Specifies the height of the space, as @var{height},
-measured in terms of the normal line 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}
-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 value of @var{ascent} must be a non-negative number no
-greater than 100.
+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{:height} 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:
+
+@example
+@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
+ @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 example
+
+ 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
+multiplying 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 (image . @var{image-props})
This is in fact 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}
@code{display} property, this feature is available starting in Emacs 21.
Emacs can display a number of different image formats; some of them
-are supported only if particular support libraries are installed on your
-machine. The supported image formats include XBM, XPM (needing the
+are supported only if particular support libraries are installed on
+your machine. In some environments, Emacs allows loading 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 (needing the
libraries @code{libXpm} version 3.4k and @code{libz}), GIF (needing
@code{libungif} 4.1.0), Postscript, PBM, JPEG (needing the
@code{libjpeg} library version v6a), TIFF (needing @code{libtiff} v3.4),
@defvar image-types
This variable contains a list of those image type symbols that are
-supported in the current configuration.
+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.
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
property yourself, but it is easier to use the functions in this
section.
-@defun insert-image image &optional string area
+@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{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 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 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
* 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.
-* Manipulating Button Types::
+* Manipulating Button Types::
@end menu
@node Button Properties
@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.
+in the variable @code{button-map}, which defines @key{RET},
+@key{mouse-1} (if @var{mouse-1-click-follows-link} is set),
+and @key{mouse-2} to invoke the button.
@item type
@kindex type @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{Enabling Mouse-1 to Follow Links}.
@item button
@kindex button @r{(button property)}
All buttons have a non-@code{nil} @code{button} property, which may be useful
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}
+a button, and is bound by default in the button itself to @key{RET},
+to @key{mouse-1} (if @var{mouse-1-click-follows-link} is set),
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
buffers that do not override it. @xref{Default Value}.
@end defvar
+@defopt tab-width
+The value of this variable is the spacing between tab stops used for
+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
support it (window systems). @xref{Fringes}.
@end defopt
-@defopt tab-width
-The value of this variable is the spacing between tab stops used for
-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
+@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
@item 1
The glyph for the end of a continued line (the default is @samp{\}).
Newer Emacs versions, on some platforms, display curved arrows to
-indicate truncation---the display table has no effect in these
+indicate continuation---the display table has no effect in these
situations.
@item 2
The glyph for indicating a character displayed as an octal character