@c This is part of the Emacs manual.
-@c Copyright (C) 1985, 86, 87, 93, 94, 95, 1997, 2000, 2001
-@c Free Software Foundation, Inc.
+@c Copyright (C) 1985, 1986, 1987, 1993, 1994, 1995, 1997, 2000, 2001,
+@c 2002, 2003, 2004, 2005, 2006 Free Software Foundation, Inc.
@c See file emacs.texi for copying conditions.
@node Display, Search, Registers, Top
@chapter Controlling the Display
Since only part of a large buffer fits in the window, Emacs tries to
-show a part that is likely to be interesting. Display-control commands
-allow you to specify which part of the text you want to see, and how to
-display it.
+show a part that is likely to be interesting. Display-control
+commands allow you to specify which part of the text you want to see,
+and how to display it. Many variables also affect the details of
+redisplay. Unless otherwise stated, the variables described in this
+chapter have their effect by customizing redisplay itself; therefore,
+their values only make a difference at the time of redisplay.
@menu
+* Scrolling:: Commands to move text up and down in a window.
+* Auto Scrolling:: Redisplay scrolls text automatically when needed.
+* Horizontal Scrolling:: Moving text left and right in a window.
+* Follow Mode:: Follow mode lets two windows scroll as one.
* Faces:: How to change the display style using faces.
+* Standard Faces:: Emacs' predefined faces.
* Font Lock:: Minor mode for syntactic highlighting using faces.
-* Highlight Changes:: Using colors to show where you changed the buffer.
* Highlight Interactively:: Tell Emacs what text to highlight.
-* Scrolling:: Moving text up and down in a window.
-* Horizontal Scrolling:: Moving text left and right in a window.
* Fringes:: Enabling or disabling window fringes.
+* Displaying Boundaries:: Displaying top and bottom of the buffer.
* Useless Whitespace:: Showing possibly-spurious trailing whitespace.
-* Follow Mode:: Follow mode lets two windows scroll as one.
* Selective Display:: Hiding lines with lots of indentation.
* Optional Mode Line:: Optional mode line display features.
* Text Display:: How text characters are normally displayed.
-* Display Custom:: Information on variables for customizing display.
* Cursor Display:: Features for displaying the cursor.
+* Line Truncation:: Truncating lines to fit the screen width instead
+ of continuing them to multiple screen lines.
+* Display Custom:: Information on variables for customizing display.
@end menu
+@node Scrolling
+@section Scrolling
+
+ If a buffer contains text that is too large to fit entirely within a
+window that is displaying the buffer, Emacs shows a contiguous portion of
+the text. The portion shown always contains point.
+
+@cindex scrolling
+ @dfn{Scrolling} means moving text up or down in the window so that
+different parts of the text are visible. Scrolling ``forward'' or
+``up'' means that text moves up, and new text appears at the bottom.
+Scrolling ``backward'' or ``down'' moves text down, and new text
+appears at the top.
+
+ Scrolling happens automatically if you move point past the bottom or
+top of the window. You can also scroll explicitly with the commands
+in this section.
+
+@table @kbd
+@item C-l
+Clear screen and redisplay, scrolling the selected window to center
+point vertically within it (@code{recenter}).
+@item C-v
+Scroll forward (a windowful or a specified number of lines) (@code{scroll-up}).
+@item @key{NEXT}
+@itemx @key{PAGEDOWN}
+Likewise, scroll forward.
+@item M-v
+Scroll backward (@code{scroll-down}).
+@item @key{PRIOR}
+@itemx @key{PAGEUP}
+Likewise, scroll backward.
+@item @var{arg} C-l
+Scroll so point is on line @var{arg} (@code{recenter}).
+@item C-M-l
+Scroll heuristically to bring useful information onto the screen
+(@code{reposition-window}).
+@end table
+
+@kindex C-l
+@findex recenter
+ The most basic scrolling command is @kbd{C-l} (@code{recenter}) with
+no argument. It scrolls the selected window so that point is halfway
+down from the top of the window. On a text terminal, it also clears
+the screen and redisplays all windows. That is useful in case the
+screen is garbled (@pxref{Screen Garbled}).
+
+@kindex C-v
+@kindex M-v
+@kindex NEXT
+@kindex PRIOR
+@kindex PAGEDOWN
+@kindex PAGEUP
+@findex scroll-up
+@findex scroll-down
+ To read the buffer a windowful at a time, use @kbd{C-v}
+(@code{scroll-up}) with no argument. This scrolls forward by nearly
+the whole window height. The effect is to take the two lines at the
+bottom of the window and put them at the top, followed by nearly a
+whole windowful of lines that were not previously visible. If point
+was in the text that scrolled off the top, it ends up at the new top
+of the window.
+
+@vindex next-screen-context-lines
+ @kbd{M-v} (@code{scroll-down}) with no argument scrolls backward in
+a similar way, also with overlap. The number of lines of overlap that
+the @kbd{C-v} or @kbd{M-v} commands leave is controlled by the
+variable @code{next-screen-context-lines}; by default, it is 2. The
+function keys @key{NEXT} and @key{PRIOR}, or @key{PAGEDOWN} and
+@key{PAGEUP}, are equivalent to @kbd{C-v} and @kbd{M-v}.
+
+ The commands @kbd{C-v} and @kbd{M-v} with a numeric argument scroll
+the text in the selected window up or down a few lines. @kbd{C-v}
+with an argument moves the text and point up, together, that many
+lines; it brings the same number of new lines into view at the bottom
+of the window. @kbd{M-v} with numeric argument scrolls the text
+downward, bringing that many new lines into view at the top of the
+window. @kbd{C-v} with a negative argument is like @kbd{M-v} and vice
+versa.
+
+ The names of scroll commands are based on the direction that the
+text moves in the window. Thus, the command to scroll forward is
+called @code{scroll-up} because it moves the text upward on the
+screen. The keys @key{PAGEDOWN} and @key{PAGEUP} derive their names
+and customary meanings from a different convention that developed
+elsewhere; hence the strange result that @key{PAGEDOWN} runs
+@code{scroll-up}.
+
+@vindex scroll-preserve-screen-position
+ Some users like the full-screen scroll commands to keep point at the
+same screen line. To enable this behavior, set the variable
+@code{scroll-preserve-screen-position} to a non-@code{nil} value. In
+this mode, when these commands would scroll the text around point off
+the screen, or within @code{scroll-margin} lines of the edge, they
+moves point to keep the same vertical position within the window.
+This mode is convenient for browsing through a file by scrolling by
+screenfuls; if you come back to the screen where you started, point
+goes back to the line where it started. However, this mode is
+inconvenient when you move to the next screen in order to move point
+to the text there.
+
+ Another way to do scrolling is with @kbd{C-l} with a numeric argument.
+@kbd{C-l} does not clear the screen when given an argument; it only scrolls
+the selected window. With a positive argument @var{n}, it repositions text
+to put point @var{n} lines down from the top. An argument of zero puts
+point on the very top line. Point does not move with respect to the text;
+rather, the text and point move rigidly on the screen. @kbd{C-l} with a
+negative argument puts point that many lines from the bottom of the window.
+For example, @kbd{C-u - 1 C-l} puts point on the bottom line, and @kbd{C-u
+- 5 C-l} puts it five lines from the bottom. @kbd{C-u C-l} scrolls to put
+point at the center (vertically) of the selected window.
+
+@kindex C-M-l
+@findex reposition-window
+ The @kbd{C-M-l} command (@code{reposition-window}) scrolls the current
+window heuristically in a way designed to get useful information onto
+the screen. For example, in a Lisp file, this command tries to get the
+entire current defun onto the screen if possible.
+
+@node Auto Scrolling
+@section Automatic Scrolling
+
+@vindex scroll-conservatively
+ Redisplay scrolls the buffer automatically when point moves out of
+the visible portion of the text. The purpose of automatic scrolling
+is to make point visible, but you can customize many aspects of how
+this is done.
+
+ Normally, automatic scrolling centers point vertically within the
+window. However, if you set @code{scroll-conservatively} to a small
+number @var{n}, then if you move point just a little off the
+screen---less than @var{n} lines---then Emacs scrolls the text just
+far enough to bring point back on screen. By default,
+@code{scroll-conservatively} is@tie{}0.
+
+@cindex aggressive scrolling
+@vindex scroll-up-aggressively
+@vindex scroll-down-aggressively
+ When the window does scroll by a longer distance, you can control
+how aggressively it scrolls, by setting the variables
+@code{scroll-up-aggressively} and @code{scroll-down-aggressively}.
+The value of @code{scroll-up-aggressively} should be either
+@code{nil}, or a fraction @var{f} between 0 and 1. A fraction
+specifies where on the screen to put point when scrolling upward.
+More precisely, when a window scrolls up because point is above the
+window start, the new start position is chosen to put point @var{f}
+part of the window height from the top. The larger @var{f}, the more
+aggressive the scrolling.
+
+ @code{nil}, which is the default, scrolls to put point at the center.
+So it is equivalent to .5.
+
+ Likewise, @code{scroll-down-aggressively} is used for scrolling
+down. The value, @var{f}, specifies how far point should be placed
+from the bottom of the window; thus, as with
+@code{scroll-up-aggressively}, a larger value is more aggressive.
+
+@vindex scroll-margin
+ The variable @code{scroll-margin} restricts how close point can come
+to the top or bottom of a window. Its value is a number of screen
+lines; if point comes within that many lines of the top or bottom of the
+window, Emacs recenters the window. By default, @code{scroll-margin} is
+0.
+
+@node Horizontal Scrolling
+@section Horizontal Scrolling
+@cindex horizontal scrolling
+
+ @dfn{Horizontal scrolling} means shifting all the lines sideways
+within a window---so that some of the text near the left margin is not
+displayed at all. When the text in a window is scrolled horizontally,
+text lines are truncated rather than continued (@pxref{Line
+Truncation}). Whenever a window shows truncated lines, Emacs
+automatically updates its horizontal scrolling whenever point moves
+off the left or right edge of the screen. You can also use these
+commands to do explicit horizontal scrolling.
+
+@table @kbd
+@item C-x <
+Scroll text in current window to the left (@code{scroll-left}).
+@item C-x >
+Scroll to the right (@code{scroll-right}).
+@end table
+
+@kindex C-x <
+@kindex C-x >
+@findex scroll-left
+@findex scroll-right
+ The command @kbd{C-x <} (@code{scroll-left}) scrolls the selected
+window to the left by @var{n} columns with argument @var{n}. This moves
+part of the beginning of each line off the left edge of the window.
+With no argument, it scrolls by almost the full width of the window (two
+columns less, to be precise).
+
+ @kbd{C-x >} (@code{scroll-right}) scrolls similarly to the right. The
+window cannot be scrolled any farther to the right once it is displayed
+normally (with each line starting at the window's left margin);
+attempting to do so has no effect. This means that you don't have to
+calculate the argument precisely for @w{@kbd{C-x >}}; any sufficiently large
+argument will restore the normal display.
+
+ If you use those commands to scroll a window horizontally, that sets
+a lower bound for automatic horizontal scrolling. Automatic scrolling
+will continue to scroll the window, but never farther to the right
+than the amount you previously set by @code{scroll-left}.
+
+@vindex hscroll-margin
+ The value of the variable @code{hscroll-margin} controls how close
+to the window's edges point is allowed to get before the window will
+be automatically scrolled. It is measured in columns. If the value
+is 5, then moving point within 5 columns of the edge causes horizontal
+scrolling away from that edge.
+
+@vindex hscroll-step
+ The variable @code{hscroll-step} determines how many columns to
+scroll the window when point gets too close to the edge. If it's
+zero, horizontal scrolling centers point horizontally within the
+window. If it's a positive integer, it specifies the number of
+columns to scroll by. If it's a floating-point number, it specifies
+the fraction of the window's width to scroll by. The default is zero.
+
+@vindex auto-hscroll-mode
+ To disable automatic horizontal scrolling, set the variable
+@code{auto-hscroll-mode} to @code{nil}.
+
+@node Follow Mode
+@section Follow Mode
+@cindex Follow mode
+@cindex mode, Follow
+@findex follow-mode
+@cindex windows, synchronizing
+@cindex synchronizing windows
+
+ @dfn{Follow mode} is a minor mode that makes two windows, both
+showing the same buffer, scroll as a single tall ``virtual window.''
+To use Follow mode, go to a frame with just one window, split it into
+two side-by-side windows using @kbd{C-x 3}, and then type @kbd{M-x
+follow-mode}. From then on, you can edit the buffer in either of the
+two windows, or scroll either one; the other window follows it.
+
+ In Follow mode, if you move point outside the portion visible in one
+window and into the portion visible in the other window, that selects
+the other window---again, treating the two as if they were parts of
+one large window.
+
+ To turn off Follow mode, type @kbd{M-x follow-mode} a second time.
+
@node Faces
@section Using Multiple Typefaces
@cindex faces
- Emacs supports using multiple styles of displaying characters. Each
-style is called a @dfn{face}. Each face can specify various @dfn{face
-attributes}, such as the font family, the height, weight and slant of
-the characters, the foreground and background color, and underlining
-or overlining. A face does not have to specify all of these
-attributes; often it inherits many of them from another face.
+ You can specify various styles for displaying text using
+@dfn{faces}. Each face can specify various @dfn{face attributes},
+such as the font family, the height, weight and slant of the
+characters, the foreground and background color, and underlining or
+overlining. A face does not have to specify all of these attributes;
+often it inherits most of them from another face.
- On a window system, all the Emacs face attributes are meaningful.
-On a character terminal, only some of them work. Some character
+ On graphical display, all the Emacs face attributes are meaningful.
+On a text-only terminal, only some of them work. Some text-only
terminals support inverse video, bold, and underline attributes; some
-support colors. Character terminals generally do not support changing
+support colors. Text-only terminals generally do not support changing
the height and width or the font family.
- Features which rely on text in multiple faces (such as Font Lock mode)
-will also work on non-windowed terminals that can display more than one
-face, whether by colors or underlining and emboldening. This includes
-the console on GNU/Linux, an @code{xterm} which supports colors, the
-MS-DOS display (@pxref{MS-DOS}), and the MS-Windows version invoked with
-the @option{-nw} option. Emacs determines automatically whether the
-terminal has this capability.
+ Emacs uses faces automatically for highlighting, through the work of
+Font Lock mode. @xref{Font Lock}, for more information about Font
+Lock mode and syntactic highlighting. You can print out the buffer
+with the highlighting that appears on your screen using the command
+@code{ps-print-buffer-with-faces}. @xref{PostScript}.
You control the appearance of a part of the text in the buffer by
specifying the face or faces to use for it. The style of display used
background colors for the current frame only; see @ref{Frame
Parameters}.)
- Emacs 21 can correctly display variable-width fonts, but Emacs
-commands that calculate width and indentation do not know how to
-calculate variable widths. This can sometimes lead to incorrect
-results when you use variable-width fonts. In particular, indentation
-commands can give inconsistent results, so we recommend you avoid
-variable-width fonts for editing program source code. Filling will
-sometimes make lines too long or too short. We plan to address these
-issues in future Emacs versions.
+ Emacs can correctly display variable-width fonts, but Emacs commands
+that calculate width and indentation do not know how to calculate
+variable widths. This can sometimes lead to incorrect results when
+you use variable-width fonts. In particular, indentation commands can
+give inconsistent results, so we recommend you avoid variable-width
+fonts for editing program source code. Filling will sometimes make
+lines too long or too short. We plan to address these issues in
+future Emacs versions.
+
+@node Standard Faces
+@section Standard Faces
@findex list-faces-display
- To see what faces are currently defined, and what they look like, type
-@kbd{M-x list-faces-display}. It's possible for a given face to look
-different in different frames; this command shows the appearance in the
-frame in which you type it. Here's a list of the standard defined
-faces:
+ To see what faces are currently defined, and what they look like,
+type @kbd{M-x list-faces-display}. It's possible for a given face to
+look different in different frames; this command shows the appearance
+in the frame in which you type it.
+
+ Here are the standard faces for specifying text appearance. You can
+apply them to specific text when you want the effects they produce.
@table @code
@item default
-This face is used for ordinary text that doesn't specify any other face.
-@item mode-line
-This face is used for the mode line of the currently selected window.
-By default, it's drawn with shadows for a ``raised'' effect on window
-systems, and drawn as the inverse of the default face on non-windowed
-terminals. @xref{Display Custom}.
-@item mode-line-inactive
-Like @code{mode-line}, but used for mode lines of the windows other
-than the selected one (if @code{mode-line-in-non-selected-windows} is
-non-@code{nil}). This face inherits from @code{mode-line}, so changes
-in that face affect mode lines in all windows.
-@item header-line
-Similar to @code{mode-line} for a window's header line. Most modes
-don't use the header line, but the Info mode does.
-@item minibuffer-prompt
-This face is used for the prompt strings displayed in the minibuffer.
+This face is used for ordinary text that doesn't specify any face.
+@item bold
+This face uses a bold variant of the default 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
+This face uses an italic variant of the default font, if it has one.
+@item bold-italic
+This face uses a bold italic variant of the default font, if it has one.
+@item underline
+This face underlines text.
+@item fixed-pitch
+This face forces use of a particular fixed-width font.
+@item variable-pitch
+This face forces use of a particular variable-width font. It's
+reasonable to customize this face to use a different variable-width font,
+if you like, but you should not make it a fixed-width font.
+@item shadow
+This face is used for making the text less noticeable than the surrounding
+ordinary text. Usually this can be achieved by using shades of gray in
+contrast with either black or white default foreground color.
+@end table
+
+ Here's an incomplete list of faces used to highlight parts of the
+text temporarily for specific purposes. (Many other modes define
+their own faces for this purpose.)
+
+@table @code
@item highlight
This face is used for highlighting portions of text, in various modes.
For example, mouse-sensitive text is highlighted using this face.
@item isearch
-This face is used for highlighting Isearch matches.
-@item isearch-lazy-highlight-face
-This face is used for lazy highlighting of Isearch matches other than
-the current one.
+This face is used for highlighting the current Isearch match.
+@item query-replace
+This face is used for highlighting the current Query Replace match.
+@item lazy-highlight
+This face is used for lazy highlighting of Isearch and Query Replace
+matches other than the current one.
@item region
This face is used for displaying a selected region (when Transient Mark
mode is enabled---see below).
@item secondary-selection
This face is used for displaying a secondary X selection (@pxref{Secondary
Selection}).
-@item bold
-This face uses a bold variant of the default font, if it has one.
-@item italic
-This face uses an italic variant of the default font, if it has one.
-@item bold-italic
-This face uses a bold italic variant of the default font, if it has one.
-@item underline
-This face underlines text.
-@item fixed-pitch
-The basic fixed-pitch face.
+@item trailing-whitespace
+The face for highlighting excess spaces and tabs at the end of a line
+when @code{show-trailing-whitespace} is non-@code{nil}; see
+@ref{Useless Whitespace}.
+@item nobreak-space
+The face for displaying the character ``nobreak space.''
+@item escape-glyph
+The face for highlighting the @samp{\} or @samp{^} that indicates
+a control character. It's also used when @samp{\} indicates a
+nobreak space or nobreak (soft) hyphen.
+@end table
+
+@cindex @code{region} face
+ When Transient Mark mode is enabled, the text of the region is
+highlighted when the mark is active. This uses the face named
+@code{region}; you can control the style of highlighting by changing the
+style of this face (@pxref{Face Customization}). @xref{Transient Mark},
+for more information about Transient Mark mode and activation and
+deactivation of the mark.
+
+ These faces control the appearance of parts of the Emacs frame.
+They exist as faces to provide a consistent way to customize the
+appearance of these parts of the frame.
+
+@table @code
+@item mode-line
+@itemx modeline
+This face is used for the mode line of the currently selected window,
+and for menu bars when toolkit menus are not used. By default, it's
+drawn with shadows for a ``raised'' effect on graphical displays, and
+drawn as the inverse of the default face on non-windowed terminals.
+@code{modeline} is an alias for the @code{mode-line} face, for
+compatibility with old Emacs versions.
+@item mode-line-inactive
+Like @code{mode-line}, but used for mode lines of the windows other
+than the selected one (if @code{mode-line-in-non-selected-windows} is
+non-@code{nil}). This face inherits from @code{mode-line}, so changes
+in that face affect mode lines in all windows.
+@item mode-line-highlight
+Like @code{highlight}, but used for portions of text on mode lines.
+@item mode-line-buffer-id
+This face is used for buffer identification parts in the mode line.
+@item header-line
+Similar to @code{mode-line} for a window's header line, which appears
+at the top of a window just as the mode line appears at the bottom.
+Most windows do not have a header line---only some special modes, such
+Info mode, create one.
+@item vertical-border
+This face is used for the vertical divider between windows.
+By default this face inherits from the @code{mode-line-inactive} face
+on character terminals. On graphical displays the foreground color of
+this face is used for the vertical line between windows without
+scrollbars.
+@item minibuffer-prompt
+@cindex @code{minibuffer-prompt} face
+@vindex minibuffer-prompt-properties
+This face is used for the prompt strings displayed in the minibuffer.
+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. (This variable takes
+effect when you enter the minibuffer.)
@item fringe
-@cindex fringe
+@cindex @code{fringe} face
The face for the fringes to the left and right of windows on graphic
displays. (The fringes are the narrow portions of the Emacs frame
between the text area and the window's right and left borders.)
+@xref{Fringes}.
@item scroll-bar
This face determines the visual appearance of the scroll bar.
+@xref{Scroll Bars}.
@item border
This face determines the color of the frame border.
@item cursor
@item mouse
This face determines the color of the mouse pointer.
@item tool-bar
-This is the basic tool-bar face. No text appears in the tool bar, but the
-colors of this face affect the appearance of tool bar icons.
+This face determines the color of tool bar icons. @xref{Tool Bars}.
@item tooltip
-This face is used for tooltips.
+This face is used for tooltips. @xref{Tooltips}.
@item menu
-This face determines the colors and font of Emacs's menus. Setting the
-font of LessTif/Motif menus is currently not supported; attempts to set
-the font are ignored in this case.
-@item trailing-whitespace
-The face for highlighting trailing whitespace when
-@code{show-trailing-whitespace} is non-nil; see @ref{Trailing Whitespace}.
-@item variable-pitch
-The basic variable-pitch face.
+@cindex menu bar appearance
+@cindex @code{menu} face, no effect if customized
+@cindex customization of @code{menu} face
+This face determines the colors and font of Emacs's menus. @xref{Menu
+Bars}. Setting the font of LessTif/Motif menus is currently not
+supported; attempts to set the font are ignored in this case.
+Likewise, attempts to customize this face in Emacs built with GTK and
+in the MS-Windows/Mac ports are ignored by the respective GUI toolkits;
+you need to use system-wide styles and options to change the
+appearance of the menus.
@end table
-@cindex @code{region} face
- When Transient Mark mode is enabled, the text of the region is
-highlighted when the mark is active. This uses the face named
-@code{region}; you can control the style of highlighting by changing the
-style of this face (@pxref{Face Customization}). @xref{Transient Mark},
-for more information about Transient Mark mode and activation and
-deactivation of the mark.
-
- One easy way to use faces is to turn on Font Lock mode. This minor
-mode, which is always local to a particular buffer, arranges to
-choose faces according to the syntax of the text you are editing. It
-can recognize comments and strings in most languages; in several
-languages, it can also recognize and properly highlight various other
-important constructs. @xref{Font Lock}, for more information about
-Font Lock mode and syntactic highlighting.
-
- You can print out the buffer with the highlighting that appears
-on your screen using the command @code{ps-print-buffer-with-faces}.
-@xref{PostScript}.
-
@node Font Lock
@section Font Lock mode
@cindex Font Lock mode
@cindex mode, Font Lock
@cindex syntax highlighting and coloring
- Font Lock mode is a minor mode, always local to a particular
-buffer, which highlights (or ``fontifies'') using various faces
-according to the syntax of the text you are editing. It can
-recognize comments and strings in most languages; in several
-languages, it can also recognize and properly highlight various other
-important constructs---for example, names of functions being defined
-or reserved keywords.
+ Font Lock mode is a minor mode, always local to a particular buffer,
+which highlights (or ``fontifies'') the buffer contents according to
+the syntax of the text you are editing. It can recognize comments and
+strings in most languages; in several languages, it can also recognize
+and properly highlight various other important constructs---for
+example, names of functions being defined or reserved keywords.
+Some special modes, such as Occur mode and Info mode, have completely
+specialized ways of assigning fonts for Font Lock mode.
@findex font-lock-mode
-@findex turn-on-font-lock
- The command @kbd{M-x font-lock-mode} turns Font Lock mode on or off
-according to the argument, and toggles the mode when it has no argument.
-The function @code{turn-on-font-lock} unconditionally enables Font Lock
-mode. This is useful in mode-hook functions. For example, to enable
-Font Lock mode whenever you edit a C file, you can do this:
-
-@example
-(add-hook 'c-mode-hook 'turn-on-font-lock)
-@end example
+ Font Lock mode is turned on by default in all modes which support it.
+You can toggle font-lock for each buffer with the command @kbd{M-x
+font-lock-mode}. Using a positive argument unconditionally turns Font
+Lock mode on, and a negative or zero argument turns it off.
@findex global-font-lock-mode
@vindex global-font-lock-mode
- To turn on Font Lock mode automatically in all modes which support
-it, customize the user option @code{global-font-lock-mode} or use the
-function @code{global-font-lock-mode} in your @file{.emacs} file, like
-this:
+ If you do not wish Font Lock mode to be turned on by default,
+customize the variable @code{global-font-lock-mode} using the Customize
+interface (@pxref{Easy Customization}), or use the function
+@code{global-font-lock-mode} in your @file{.emacs} file, like this:
@example
-(global-font-lock-mode 1)
+(global-font-lock-mode 0)
@end example
- Font Lock mode uses several specifically named faces to do its job,
-including @code{font-lock-string-face}, @code{font-lock-comment-face},
-and others. The easiest way to find them all is to use completion
-on the face name in @code{set-face-foreground}.
+@noindent
+This variable, like all the variables that control Font Lock mode,
+take effect whenever fontification is done; that is, potentially at
+any time.
- To change the colors or the fonts used by Font Lock mode to fontify
-different parts of text, just change these faces. There are
-two ways to do it:
+@findex turn-on-font-lock
+ If you have disabled Global Font Lock mode, you can still enable Font
+Lock for specific major modes by adding the function
+@code{turn-on-font-lock} to the mode hooks (@pxref{Hooks}). For
+example, to enable Font Lock mode for editing C files, you can do this:
-@itemize @bullet
-@item
-Invoke @kbd{M-x set-face-foreground} or @kbd{M-x set-face-background}
-to change the colors of a particular face used by Font Lock.
-@xref{Faces}. The command @kbd{M-x list-faces-display} displays all
-the faces currently known to Emacs, including those used by Font Lock.
+@example
+(add-hook 'c-mode-hook 'turn-on-font-lock)
+@end example
-@item
-Customize the faces interactively with @kbd{M-x customize-face}, as
-described in @ref{Face Customization}.
-@end itemize
+ Font Lock mode uses several specifically named faces to do its job,
+including @code{font-lock-string-face}, @code{font-lock-comment-face},
+and others. The easiest way to find them all is to use @kbd{M-x
+customize-group @key{RET} font-lock-faces @key{RET}}. You can then
+use that customization buffer to customize the appearance of these
+faces. @xref{Face Customization}.
- To get the full benefit of Font Lock mode, you need to choose a
-default font which has bold, italic, and bold-italic variants; or else
-you need to have a color or gray-scale screen.
+ You can also customize these faces using @kbd{M-x
+set-face-foreground} or @kbd{M-x set-face-background}. @xref{Faces}.
@vindex font-lock-maximum-decoration
The variable @code{font-lock-maximum-decoration} specifies the
@vindex font-lock-maximum-size
Fontification can be too slow for large buffers, so you can suppress
-it. The variable @code{font-lock-maximum-size} specifies a buffer size,
-beyond which buffer fontification is suppressed.
+it for buffers above a certain size. The variable
+@code{font-lock-maximum-size} specifies a buffer size, beyond which
+buffer fontification is suppressed.
@c @w is used below to prevent a bad page-break.
@vindex font-lock-beginning-of-syntax-function
@cindex brace in column zero and fontification
Comment and string fontification (or ``syntactic'' fontification)
relies on analysis of the syntactic structure of the buffer text. For
-the sake of speed, some modes, including C mode and Lisp mode,
-rely on a special convention: an open-parenthesis or open-brace in the
-leftmost column always defines the @w{beginning} of a defun, and is
-thus always outside any string or comment. (@xref{Left Margin
-Paren}.) If you don't follow this convention, Font Lock mode can
-misfontify the text that follows an open-parenthesis or open-brace in
-the leftmost column that is inside a string or comment.
+the sake of speed, some modes, including Lisp mode, rely on a special
+convention: an open-parenthesis or open-brace in the leftmost column
+always defines the @w{beginning} of a defun, and is thus always
+outside any string or comment. (@xref{Left Margin Paren}.) If you
+don't follow this convention, Font Lock mode can misfontify the text
+that follows an open-parenthesis or open-brace in the leftmost column
+that is inside a string or comment.
@cindex slow display during scrolling
The variable @code{font-lock-beginning-of-syntax-function} (always
buffer-local) specifies how Font Lock mode can find a position
-guaranteed to be outside any comment or string. In modes which use the
-leftmost column parenthesis convention, the default value of the variable
-is @code{beginning-of-defun}---that tells Font Lock mode to use the
-convention. If you set this variable to @code{nil}, Font Lock no longer
-relies on the convention. This avoids incorrect results, but the price
-is that, in some cases, fontification for a changed text must rescan
-buffer text from the beginning of the buffer. This can considerably
-slow down redisplay while scrolling, particularly if you are close to
-the end of a large buffer.
-
-@findex font-lock-add-keywords
- Font Lock highlighting patterns already exist for many modes, but you
-may want to fontify additional patterns. You can use the function
-@code{font-lock-add-keywords}, to add your own highlighting patterns for
-a particular mode. For example, to highlight @samp{FIXME:} words in C
-comments, use this:
-
-@example
-(font-lock-add-keywords
- 'c-mode
- '(("\\<\\(FIXME\\):" 1 font-lock-warning-face t)))
-@end example
-
-@findex font-lock-remove-keywords
- To remove keywords from the font-lock highlighting patterns, use the
-function @code{font-lock-remove-keywords}.
-
-@cindex just-in-time (JIT) font-lock
-@cindex background syntax highlighting
- Fontifying large buffers can take a long time. To avoid large
-delays when a file is visited, Emacs fontifies only the visible
-portion of a buffer. As you scroll through the buffer, each portion
-that becomes visible is fontified as soon as it is displayed. The
-parts of the buffer that are not displayed are fontified
-``stealthily'', in the background, i.e.@: when Emacs is idle. You can
-control this background fontification, called @dfn{Just-In-Time}, or
-@dfn{JIT} Font Lock, by customizing various options in the
-customization group @samp{jit-lock}. @xref{Specific Customization}.
-
-@node Highlight Changes
-@section Highlight Changes Mode
-
-@findex highlight-changes-mode
- Use @kbd{M-x highlight-changes-mode} to enable a minor mode
-that uses faces (colors, typically) to indicate which parts of
-the buffer were changed most recently.
-
-@node Highlight Interactively
-@section Interactive Highlighting by Matching
-@cindex highlighting by matching
-@cindex interactive highlighting
-
- It is sometimes useful to highlight the strings that match a certain
-regular expression. For example, you might wish to see all the
-references to a certain variable in a program source file, or highlight
-certain parts in a voluminous output of some program, or make certain
-cliches stand out in an article.
-
-@findex hi-lock-mode
- Use the @kbd{M-x hi-lock-mode} command to turn on a minor mode that
-allows you to specify regular expressions of the text to be
-highlighted. Hi-lock mode works like Font Lock (@pxref{Font Lock}),
-except that it lets you specify explicitly what parts of text to
-highlight. You control Hi-lock mode with these commands:
-
-@table @kbd
-@item C-x w h @var{regexp} @key{RET} @var{face} @key{RET}
-@kindex C-x w h
-@findex highlight-regexp
-Highlight text that matches
-@var{regexp} using face @var{face} (@code{highlight-regexp}).
-By using this command more than once, you can highlight various
-parts of the text in different ways.
-
-@item C-x w r @var{regexp} @key{RET}
-@kindex C-x w r
-@findex unhighlight-regexp
-Unhighlight @var{regexp} (@code{unhighlight-regexp}). You must enter
-one of the regular expressions currently specified for highlighting.
-(You can use completion, or choose from a menu, to enter one of them
-conveniently.)
-
-@item C-x w l @var{regexp} @key{RET} @var{face} @key{RET}
-@kindex C-x w l
-@findex highlight-lines-matching-regexp
-@cindex lines, highlighting
-@cindex highlighting lines of text
-Highlight entire lines containing a match for @var{regexp}, using face
-@var{face} (@code{highlight-lines-matching-regexp}).
-
-@item C-x w b
-@kindex C-x w b
-@findex hi-lock-write-interactive-patterns
-Insert all the current highlighting regexp/face pairs into the buffer
-at point, with comment delimiters to prevent them from changing your
-program. This key binding runs the
-@code{hi-lock-write-interactive-patterns} command.
-
-These patterns will be read the next time you visit the file while
-Hi-lock mode is enabled, or whenever you use the @kbd{M-x
-hi-lock-find-patterns} command.
-
-@item C-x w i
-@kindex C-x w i
-@findex hi-lock-find-patterns
-@vindex hi-lock-exclude-modes
-Re-read regexp/face pairs in the current buffer
-(@code{hi-lock-write-interactive-patterns}). The list of pairs is
-found no matter where in the buffer it may be.
-
-This command does nothing if the major mode is a member of the list
-@code{hi-lock-exclude-modes}.
-@end table
-
-@node Scrolling
-@section Scrolling
-
- If a buffer contains text that is too large to fit entirely within a
-window that is displaying the buffer, Emacs shows a contiguous portion of
-the text. The portion shown always contains point.
-
-@cindex scrolling
- @dfn{Scrolling} means moving text up or down in the window so that
-different parts of the text are visible. Scrolling forward means that text
-moves up, and new text appears at the bottom. Scrolling backward moves
-text down and new text appears at the top.
-
- Scrolling happens automatically if you move point past the bottom or top
-of the window. You can also explicitly request scrolling with the commands
-in this section.
-
-@table @kbd
-@item C-l
-Clear screen and redisplay, scrolling the selected window to center
-point vertically within it (@code{recenter}).
-@item C-v
-Scroll forward (a windowful or a specified number of lines) (@code{scroll-up}).
-@item @key{NEXT}
-@itemx @key{PAGEDOWN}
-Likewise, scroll forward.
-@item M-v
-Scroll backward (@code{scroll-down}).
-@item @key{PRIOR}
-@itemx @key{PAGEUP}
-Likewise, scroll backward.
-@item @var{arg} C-l
-Scroll so point is on line @var{arg} (@code{recenter}).
-@item C-M-l
-Scroll heuristically to bring useful information onto the screen
-(@code{reposition-window}).
-@end table
-
-@kindex C-l
-@findex recenter
- The most basic scrolling command is @kbd{C-l} (@code{recenter}) with
-no argument. It clears the entire screen and redisplays all windows.
-In addition, it scrolls the selected window so that point is halfway
-down from the top of the window.
-
-@kindex C-v
-@kindex M-v
-@kindex NEXT
-@kindex PRIOR
-@kindex PAGEDOWN
-@kindex PAGEUP
-@findex scroll-up
-@findex scroll-down
-@vindex next-screen-context-lines
- To read the buffer a windowful at a time, use @kbd{C-v}
-(@code{scroll-up}) with no argument. This scrolls forward by nearly
-the whole window height. The effect is to take the two lines at the
-bottom of the window and put them at the top, followed by nearly a
-whole windowful of lines that were not previously visible. If point
-was in the text that scrolled off the top, it ends up at the new top
-of the window.
-
- @kbd{M-v} (@code{scroll-down}) with no argument scrolls backward in
-a similar way, also with overlap. The number of lines of overlap
-across a @kbd{C-v} or @kbd{M-v} is controlled by the variable
-@code{next-screen-context-lines}; by default, it is 2. The function
-keys @key{NEXT} and @key{PRIOR}, or @key{PAGEDOWN} and @key{PAGEUP},
-are equivalent to @kbd{C-v} and @kbd{M-v}.
-
- The commands @kbd{C-v} and @kbd{M-v} with a numeric argument scroll
-the text in the selected window up or down a few lines. @kbd{C-v}
-with an argument moves the text and point up, together, that many
-lines; it brings the same number of new lines into view at the bottom
-of the window. @kbd{M-v} with numeric argument scrolls the text
-downward, bringing that many new lines into view at the top of the
-window. @kbd{C-v} with a negative argument is like @kbd{M-v} and vice
-versa.
-
- The names of scroll commands are based on the direction that the
-text moves in the window. Thus, the command to scroll forward is
-called @code{scroll-up} because it moves the text upward on the
-screen. The keys @key{PAGEDOWN} and @key{PAGEUP} derive their names
-and customary meanings from a different convention that developed
-elsewhere; hence the strange result that @key{PAGEDOWN} runs
-@code{scroll-up}.
-
-@vindex scroll-preserve-screen-position
- Some users like the full-screen scroll commands to keep point at the
-same screen line. To enable this behavior, set the variable
-@code{scroll-preserve-screen-position} to a non-@code{nil} value. This
-mode is convenient for browsing through a file by scrolling by
-screenfuls; if you come back to the screen where you started, point goes
-back to the line where it started. However, this mode is inconvenient
-when you move to the next screen in order to move point to the text
-there.
-
- Another way to do scrolling is with @kbd{C-l} with a numeric argument.
-@kbd{C-l} does not clear the screen when given an argument; it only scrolls
-the selected window. With a positive argument @var{n}, it repositions text
-to put point @var{n} lines down from the top. An argument of zero puts
-point on the very top line. Point does not move with respect to the text;
-rather, the text and point move rigidly on the screen. @kbd{C-l} with a
-negative argument puts point that many lines from the bottom of the window.
-For example, @kbd{C-u - 1 C-l} puts point on the bottom line, and @kbd{C-u
-- 5 C-l} puts it five lines from the bottom. @kbd{C-u C-l} scrolls to put
-point at the center (vertically) of the selected window.
-
-@kindex C-M-l
-@findex reposition-window
- The @kbd{C-M-l} command (@code{reposition-window}) scrolls the current
-window heuristically in a way designed to get useful information onto
-the screen. For example, in a Lisp file, this command tries to get the
-entire current defun onto the screen if possible.
-
-@vindex scroll-conservatively
- Scrolling happens automatically when point moves out of the visible
-portion of the text. Normally, automatic scrolling centers point
-vertically within the window. However, if you set
-@code{scroll-conservatively} to a small number @var{n}, then if you
-move point just a little off the screen---less than @var{n}
-lines---then Emacs scrolls the text just far enough to bring point
-back on screen. By default, @code{scroll-conservatively} is 0.
+guaranteed to be outside any comment or string. In modes which use the
+leftmost column parenthesis convention, the default value of the variable
+is @code{beginning-of-defun}---that tells Font Lock mode to use the
+convention. If you set this variable to @code{nil}, Font Lock no longer
+relies on the convention. This avoids incorrect results, but the price
+is that, in some cases, fontification for a changed text must rescan
+buffer text from the beginning of the buffer. This can considerably
+slow down redisplay while scrolling, particularly if you are close to
+the end of a large buffer.
-@cindex aggressive scrolling
-@vindex scroll-up-aggressively
-@vindex scroll-down-aggressively
- When the window does scroll by a longer distance, you can control
-how aggressively it scrolls, by setting the variables
-@code{scroll-up-aggressively} and @code{scroll-down-aggressively}.
-The value of @code{scroll-up-aggressively} should be either
-@code{nil}, or a fraction @var{f} between 0 and 1. A fraction
-specifies where on the screen to put point when scrolling upward.
-More precisely, when a window scrolls up because point is above the
-window start, the new start position is chosen to put point @var{f}
-part of the window height from the top. The larger @var{f}, the more
-aggressive the scrolling.
+@findex font-lock-add-keywords
+ Font Lock highlighting patterns already exist for many modes, but you
+may want to fontify additional patterns. You can use the function
+@code{font-lock-add-keywords}, to add your own highlighting patterns for
+a particular mode. For example, to highlight @samp{FIXME:} words in C
+comments, use this:
- @code{nil}, which is the default, scrolls to put point at the center.
-So it is equivalent to .5.
+@example
+(font-lock-add-keywords
+ 'c-mode
+ '(("\\<\\(FIXME\\):" 1 font-lock-warning-face t)))
+@end example
- Likewise, @code{scroll-down-aggressively} is used for scrolling
-down. The value, @var{f}, specifies how far point should be placed
-from the bottom of the window; thus, as with
-@code{scroll-up-aggressively}, a larger value is more aggressive.
+@findex font-lock-remove-keywords
+ To remove keywords from the font-lock highlighting patterns, use the
+function @code{font-lock-remove-keywords}. @xref{Search-based
+Fontification,,, elisp, The Emacs Lisp Reference Manual}, for
+documentation of the format of this list.
-@vindex scroll-margin
- The variable @code{scroll-margin} restricts how close point can come
-to the top or bottom of a window. Its value is a number of screen
-lines; if point comes within that many lines of the top or bottom of the
-window, Emacs recenters the window. By default, @code{scroll-margin} is
-0.
+@cindex just-in-time (JIT) font-lock
+@cindex background syntax highlighting
+ Fontifying large buffers can take a long time. To avoid large
+delays when a file is visited, Emacs fontifies only the visible
+portion of a buffer. As you scroll through the buffer, each portion
+that becomes visible is fontified as soon as it is displayed. The
+parts of the buffer that are not displayed are fontified
+``stealthily,'' in the background, i.e.@: when Emacs is idle. You can
+control this background fontification, also called @dfn{Just-In-Time}
+(or @dfn{JIT}) Lock, by customizing variables in the customization
+group @samp{jit-lock}. @xref{Specific Customization}.
-@node Horizontal Scrolling
-@section Horizontal Scrolling
-@cindex horizontal scrolling
+@node Highlight Interactively
+@section Interactive Highlighting
+@cindex highlighting by matching
+@cindex interactive highlighting
+@cindex Highlight Changes mode
- @dfn{Horizontal scrolling} means shifting all the lines sideways
-within a window---so that some of the text near the left margin is not
-displayed at all. Emacs does this automatically in any window that
-uses line truncation rather than continuation: whenever point moves
-off the left or right edge of the screen, Emacs scrolls the buffer
-horizontally to make point visible.
-
- When a window has been scrolled horizontally, text lines are truncated
-rather than continued (@pxref{Continuation Lines}), with a @samp{$}
-appearing in the first column when there is text truncated to the left,
-and in the last column when there is text truncated to the right.
+@findex highlight-changes-mode
+ Use @kbd{M-x highlight-changes-mode} to enable (or disable)
+Highlight Changes mode, a minor mode that uses faces (colors,
+typically) to indicate which parts of the buffer were changed most
+recently.
- You can use these commands to do explicit horizontal scrolling.
+@cindex Hi Lock mode
+@findex hi-lock-mode
+ Hi Lock mode is another minor mode, which highlights text that
+matches your specified regular expressions. For example, you might
+wish to see all the references to a certain variable in a program
+source file, highlight certain parts in a voluminous output of some
+program, or make certain names stand out in an article. Use the
+@kbd{M-x hi-lock-mode} command to enable (or disable) Hi Lock mode.
+To enable Hi Lock mode for all buffers, use @kbd{M-x
+global-hi-lock-mode} or place @code{(global-hi-lock-mode 1)} in your
+@file{.emacs} file.
+
+ Hi Lock mode works like Font Lock mode (@pxref{Font Lock}), except
+that you specify explicitly the regular expressions to highlight. You
+control them with these commands:
@table @kbd
-@item C-x <
-Scroll text in current window to the left (@code{scroll-left}).
-@item C-x >
-Scroll to the right (@code{scroll-right}).
-@end table
+@item C-x w h @var{regexp} @key{RET} @var{face} @key{RET}
+@kindex C-x w h
+@findex highlight-regexp
+Highlight text that matches @var{regexp} using face @var{face}
+(@code{highlight-regexp}). The highlighting will remain as long as
+the buffer is loaded. For example, to highlight all occurrences of
+the word ``whim'' using the default face (a yellow background)
+@kbd{C-x w h whim @key{RET} @key{RET}}. Any face can be used for
+highlighting, Hi Lock provides several of its own and these are
+pre-loaded into a history list. While being prompted for a face use
+@kbd{M-p} and @kbd{M-n} to cycle through them.
+
+You can use this command multiple times, specifying various regular
+expressions to highlight in different ways.
-@kindex C-x <
-@kindex C-x >
-@findex scroll-left
-@findex scroll-right
- The command @kbd{C-x <} (@code{scroll-left}) scrolls the selected
-window to the left by @var{n} columns with argument @var{n}. This moves
-part of the beginning of each line off the left edge of the window.
-With no argument, it scrolls by almost the full width of the window (two
-columns less, to be precise).
+@item C-x w r @var{regexp} @key{RET}
+@kindex C-x w r
+@findex unhighlight-regexp
+Unhighlight @var{regexp} (@code{unhighlight-regexp}).
- @kbd{C-x >} (@code{scroll-right}) scrolls similarly to the right. The
-window cannot be scrolled any farther to the right once it is displayed
-normally (with each line starting at the window's left margin);
-attempting to do so has no effect. This means that you don't have to
-calculate the argument precisely for @w{@kbd{C-x >}}; any sufficiently large
-argument will restore the normal display.
+If you invoke this from the menu, you select the expression to
+unhighlight from a list. If you invoke this from the keyboard, you
+use the minibuffer. It will show the most recently added regular
+expression; use @kbd{M-p} to show the next older expression and
+@kbd{M-n} to select the next newer expression. (You can also type the
+expression by hand, with completion.) When the expression you want to
+unhighlight appears in the minibuffer, press @kbd{@key{RET}} to exit
+the minibuffer and unhighlight it.
- If you scroll a window horizontally by hand, that sets a lower bound
-for automatic horizontal scrolling. Automatic scrolling will continue
-to scroll the window, but never farther to the right than the amount
-you previously set by @code{scroll-left}.
+@item C-x w l @var{regexp} @key{RET} @var{face} @key{RET}
+@kindex C-x w l
+@findex highlight-lines-matching-regexp
+@cindex lines, highlighting
+@cindex highlighting lines of text
+Highlight entire lines containing a match for @var{regexp}, using face
+@var{face} (@code{highlight-lines-matching-regexp}).
-@vindex hscroll-margin
- The value of the variable @code{hscroll-margin} controls how close
-to the window's edges point is allowed to get before the window will
-be automatically scrolled. It is measured in columns. If the value
-is 5, then moving point within 5 columns of the edge causes horizontal
-scrolling away from that edge.
+@item C-x w b
+@kindex C-x w b
+@findex hi-lock-write-interactive-patterns
+Insert all the current highlighting regexp/face pairs into the buffer
+at point, with comment delimiters to prevent them from changing your
+program. (This key binding runs the
+@code{hi-lock-write-interactive-patterns} command.)
-@vindex hscroll-step
- The variable @code{hscroll-step} determines how many columns to
-scroll the window when point gets too close to the edge. If it's
-zero, horizontal scrolling centers point horizontally within the
-window. If it's a positive integer, it specifies the number of
-columns to scroll by. If it's a floating-point number, it specifies
-the fraction of the window's width to scroll by. The default is zero.
+These patterns will be read the next time you visit the file while
+Hi Lock mode is enabled, or whenever you use the @kbd{M-x
+hi-lock-find-patterns} command.
-@vindex auto-hscroll-mode
- To disable automatic horizontal scrolling, set the variable
-@code{auto-hscroll-mode} to @code{nil}.
+@item C-x w i
+@kindex C-x w i
+@findex hi-lock-find-patterns
+@vindex hi-lock-exclude-modes
+Re-read regexp/face pairs in the current buffer
+(@code{hi-lock-write-interactive-patterns}). Users familiar with Font
+Lock keywords might interactively enter patterns
+(@code{highlight-regexp}), write them into the file
+(@code{hi-lock-write-interactive-patterns}), edit them, perhaps
+including different faces for different parenthesized parts of the
+match, and finally use this command
+(@code{hi-lock-write-interactive-patterns}) to have Hi Lock highlight
+them.
+
+This command does nothing if the current major mode's symbol is a member
+of the list @code{hi-lock-exclude-modes}.
+@end table
@node Fringes
@section Window Fringes
The right fringe shows a curving arrow for each screen line except the
last, indicating that ``this is not the real end.''
- The fringes indicate line truncation with short horizontale arrows
+ The fringes indicate line truncation with short horizontal arrows
meaning ``there's more text on this line which is scrolled
-horizontally out of view.'' They also indicate other things such as
-empty lines, or where a program you are debugging is executing
-(@pxref{Debuggers}).
+horizontally out of view;'' clicking the mouse on one of the arrows
+scrolls the display horizontally in the direction of the arrow. The
+fringes can also indicate other things, such as empty lines, or where a
+program you are debugging is executing (@pxref{Debuggers}).
@findex set-fringe-style
@findex fringe-mode
@kbd{M-x fringe-mode}. To enable and disable the fringes
for the selected frame, use @kbd{M-x set-fringe-style}.
+@node Displaying Boundaries
+@section Displaying Boundaries
+
+@vindex indicate-buffer-boundaries
+ On a graphical display, Emacs can indicate the buffer boundaries in
+the fringes. It indicates the first line and the last line with
+angle images in the fringes. This can be combined with up and down
+arrow images which say whether it is possible to scroll the window up
+and down.
+
+ The buffer-local variable @code{indicate-buffer-boundaries} controls
+how the buffer boundaries and window scrolling is indicated in the
+fringes. If the value is @code{left} or @code{right}, both angle and
+arrow bitmaps are displayed in the left or right fringe, respectively.
+
+ If value is an alist, each element @code{(@var{indicator} .
+@var{position})} specifies the position of one of the indicators.
+The @var{indicator} must be one of @code{top}, @code{bottom},
+@code{up}, @code{down}, or @code{t} which specifies the default
+position for the indicators not present in the alist.
+The @var{position} is one of @code{left}, @code{right}, or @code{nil}
+which specifies not to show this indicator.
+
+ For example, @code{((top . left) (t . right))} places the top angle
+bitmap in left fringe, the bottom angle bitmap in right fringe, and
+both arrow bitmaps in right fringe. To show just the angle bitmaps in
+the left fringe, but no arrow bitmaps, use @code{((top . left)
+(bottom . left))}.
+
+@vindex default-indicate-buffer-boundaries
+ The value of the variable @code{default-indicate-buffer-boundaries}
+is the default value for @code{indicate-buffer-boundaries} in buffers
+that do not override it.
+
@node Useless Whitespace
@section Useless Whitespace
It is easy to leave unnecessary spaces at the end of a line, or
empty lines at the end of a file, without realizing it. In most
cases, this @dfn{trailing whitespace} has no effect, but there are
-special circumstances where it matters.
+special circumstances where it matters. It can also be a nuisance
+that the line has ``changed,'' when the change is just spaces added or
+removed at the end.
You can make trailing whitespace at the end of a line visible on the
screen by setting the buffer-local variable
@vindex indicate-empty-lines
@vindex default-indicate-empty-lines
-@cindex empty lines
-@cindex fringes, and empty line indication
- Emacs can indicate empty lines at the end of the buffer with a
-special bitmap in the left fringe of the window. To enable this
-feature, set the buffer-local variable @code{indicate-empty-lines} to
-a non-@code{nil} value. The default value of this variable is
-controlled by the variable @code{default-indicate-empty-lines}; by
-setting that variable, you can enable or disable this feature for all
-new buffers. (This feature currently doesn't work on character
-terminals.)
-
-@node Follow Mode
-@section Follow Mode
-@cindex Follow mode
-@cindex mode, Follow
-@findex follow-mode
-@cindex windows, synchronizing
-@cindex synchronizing windows
-
- @dfn{Follow mode} is a minor mode that makes two windows showing the
-same buffer scroll as one tall ``virtual window.'' To use Follow mode,
-go to a frame with just one window, split it into two side-by-side
-windows using @kbd{C-x 3}, and then type @kbd{M-x follow-mode}. From
-then on, you can edit the buffer in either of the two windows, or scroll
-either one; the other window follows it.
-
- In Follow mode, if you move point outside the portion visible in one
-window and into the portion visible in the other window, that selects
-the other window---again, treating the two as if they were parts of
-one large window.
-
- To turn off Follow mode, type @kbd{M-x follow-mode} a second time.
+@cindex unused lines
+@cindex fringes, and unused line indication
+ Emacs can indicate unused lines at the end of the window with a
+small image in the left fringe (@pxref{Fringes}). The image appears
+for window lines that do not correspond to any buffer text. Blank
+lines at the end of the buffer then stand out because they do not have
+this image in the fringe.
+
+ To enable this feature, set the buffer-local variable
+@code{indicate-empty-lines} to a non-@code{nil} value. The default
+value of this variable is controlled by the variable
+@code{default-indicate-empty-lines}; by setting that variable, you
+can enable or disable this feature for all new buffers. (This feature
+currently doesn't work on text-only terminals.)
@node Selective Display
@section Selective Display
of columns (you specify how many columns). You can use this to get an
overview of a part of a program.
- To hide lines, type @kbd{C-x $} (@code{set-selective-display}) with a
-numeric argument @var{n}. Then lines with at least @var{n} columns of
-indentation disappear from the screen. The only indication of their
-presence is that three dots (@samp{@dots{}}) appear at the end of each
-visible line that is followed by one or more hidden ones.
+ To hide lines in the current buffer, type @kbd{C-x $}
+(@code{set-selective-display}) with a numeric argument @var{n}. Then
+lines with at least @var{n} columns of indentation disappear from the
+screen. The only indication of their presence is that three dots
+(@samp{@dots{}}) appear at the end of each visible line that is
+followed by one or more hidden ones.
The commands @kbd{C-n} and @kbd{C-p} move across the hidden lines as
if they were not there.
precedes hidden lines. Then there is no visible indication of the
hidden lines. This variable becomes local automatically when set.
+ See also @ref{Outline Mode} for another way to hide part of
+the text in a buffer.
+
@node Optional Mode Line
@section Optional Mode Line Features
+@cindex buffer size display
+@cindex display of buffer size
+@findex size-indication-mode
+ The buffer percentage @var{pos} indicates the percentage of the
+buffer above the top of the window. You can additionally display the
+size of the buffer by typing @kbd{M-x size-indication-mode} to turn on
+Size Indication mode. The size will be displayed immediately
+following the buffer percentage like this:
+
+@example
+@var{POS} of @var{SIZE}
+@end example
+
+@noindent
+Here @var{SIZE} is the human readable representation of the number of
+characters in the buffer, which means that @samp{k} for 10^3, @samp{M}
+for 10^6, @samp{G} for 10^9, etc., are used to abbreviate.
+
+@cindex narrowing, and buffer size display
+ If you have narrowed the buffer (@pxref{Narrowing}), the size of the
+accessible part of the buffer is shown.
+
@cindex line number display
@cindex display of line number
@findex line-number-mode
The current line number of point appears in the mode line when Line
Number mode is enabled. Use the command @kbd{M-x line-number-mode} to
turn this mode on and off; normally it is on. The line number appears
-before the buffer percentage @var{pos}, with the letter @samp{L} to
+after the buffer percentage @var{pos}, with the letter @samp{L} to
indicate what it is. @xref{Minor Modes}, for more information about
minor modes and about how to use this command.
@cindex narrowing, and line number display
If you have narrowed the buffer (@pxref{Narrowing}), the displayed
line number is relative to the accessible portion of the buffer.
+Thus, it isn't suitable as an argument to @code{goto-line}. (Use
+@code{what-line} command to see the line number relative to the whole
+file.)
@vindex line-number-display-limit
If the buffer is very large (larger than the value of
3D-style highlighting, like that of a button when it is not being
pressed. If you don't like this effect, you can disable the 3D
highlighting of the mode line, by customizing the attributes of the
-@code{mode-line} face in your @file{.emacs} init file, like this:
-
-@example
-(set-face-attribute 'mode-line nil :box nil)
-@end example
-
-@noindent
-Alternatively, you can turn off the box attribute in your
-@file{.Xdefaults} file:
-
-@example
-Emacs.mode-line.AttributeBox: off
-@end example
+@code{mode-line} face. @xref{Face Customization}.
@cindex non-selected windows, mode line appearance
By default, the mode line of nonselected windows is displayed in a
@code{mode-line-in-non-selected-windows} to @code{nil}; then all mode
lines are displayed in the @code{mode-line} face.
+@vindex eol-mnemonic-unix
+@vindex eol-mnemonic-dos
+@vindex eol-mnemonic-mac
+@vindex eol-mnemonic-undecided
+ You can customize the mode line display for each of the end-of-line
+formats by setting each of the variables @code{eol-mnemonic-unix},
+@code{eol-mnemonic-dos}, @code{eol-mnemonic-mac}, and
+@code{eol-mnemonic-undecided} to the strings you prefer.
+
@node Text Display
@section How Text Is Displayed
@cindex characters (in text)
- ASCII printing characters (octal codes 040 through 0176) in Emacs
+ @acronym{ASCII} printing characters (octal codes 040 through 0176) in Emacs
buffers are displayed with their graphics, as are non-ASCII multibyte
printing characters (octal codes above 0400).
- Some ASCII control characters are displayed in special ways. The
+ Some @acronym{ASCII} control characters are displayed in special ways. The
newline character (octal code 012) is displayed by starting a new line.
The tab character (octal code 011) is displayed by moving to the next
tab stop column (normally every 8 columns).
- Other ASCII control characters are normally displayed as a caret
+ Other @acronym{ASCII} control characters are normally displayed as a caret
(@samp{^}) followed by the non-control version of the character; thus,
-control-A is displayed as @samp{^A}.
-
- Non-ASCII characters 0200 through 0237 (octal) are displayed with
-octal escape sequences; thus, character code 0230 (octal) is displayed
-as @samp{\230}. The display of character codes 0240 through 0377
-(octal) may be either as escape sequences or as graphics. They do not
-normally occur in multibyte buffers, but if they do, they are displayed
-as Latin-1 graphics. In unibyte mode, if you enable European display
-they are displayed using their graphics (assuming your terminal supports
-them), otherwise as escape sequences. @xref{Single-Byte Character
-Support}.
+control-A is displayed as @samp{^A}. The caret appears in face
+@code{escape-glyph}.
-@node Display Custom
-@section Customization of Display
-
- This section contains information for customization only. Beginning
-users should skip it.
-
-@vindex mode-line-inverse-video
- The variable @code{mode-line-inverse-video} is an obsolete way of
-controlling whether the mode line is displayed in inverse video; the
-preferred way of doing this is to change the @code{mode-line} face.
-@xref{Mode Line}. However, if @code{mode-line-inverse-video} has a
-value of @code{nil}, then the @code{mode-line} face will be ignored,
-and mode-lines will be drawn using the default text face.
-@xref{Faces}.
-
-@vindex inverse-video
- If the variable @code{inverse-video} is non-@code{nil}, Emacs attempts
-to invert all the lines of the display from what they normally are.
-
-@vindex visible-bell
- If the variable @code{visible-bell} is non-@code{nil}, Emacs attempts
-to make the whole screen blink when it would normally make an audible bell
-sound. This variable has no effect if your terminal does not have a way
-to make the screen blink.@refill
-
-@vindex no-redraw-on-reenter
- When you reenter Emacs after suspending, Emacs normally clears the
-screen and redraws the entire display. On some terminals with more than
-one page of memory, it is possible to arrange the termcap entry so that
-the @samp{ti} and @samp{te} strings (output to the terminal when Emacs
-is entered and exited, respectively) switch between pages of memory so
-as to use one page for Emacs and another page for other output. Then
-you might want to set the variable @code{no-redraw-on-reenter}
-non-@code{nil}; this tells Emacs to assume, when resumed, that the
-screen page it is using still contains what Emacs last wrote there.
-
-@vindex echo-keystrokes
- The variable @code{echo-keystrokes} controls the echoing of multi-character
-keys; its value is the number of seconds of pause required to cause echoing
-to start, or zero meaning don't echo at all. @xref{Echo Area}.
+ Non-@acronym{ASCII} characters 0200 through 0237 (octal) are
+displayed with octal escape sequences; thus, character code 0230
+(octal) is displayed as @samp{\230}. The backslash appears in face
+@code{escape-glyph}.
@vindex ctl-arrow
- If the variable @code{ctl-arrow} is @code{nil}, all control characters in
+ If the variable @code{ctl-arrow} is @code{nil}, control characters in
the buffer are displayed with octal escape sequences, except for newline
and tab. Altering the value of @code{ctl-arrow} makes it local to the
current buffer; until that time, the default value is in effect. The
-default is initially @code{t}. @xref{Display Tables,, Display Tables,
-elisp, The Emacs Lisp Reference Manual}.
+default is initially @code{t}.
+
+ The display of character codes 0240 through 0377 (octal) may be
+either as escape sequences or as graphics. They do not normally occur
+in multibyte buffers, but if they do, they are displayed as Latin-1
+graphics. In unibyte mode, if you enable European display they are
+displayed using their graphics (assuming your terminal supports them),
+otherwise as escape sequences. @xref{Unibyte Mode}.
+
+@vindex nobreak-char-display
+@cindex no-break space, display
+@cindex no-break hyphen, display
+@cindex soft hyphen, display
+ Some character sets define ``no-break'' versions of the space and
+hyphen characters, which are used where a line should not be broken.
+Emacs normally displays these characters with special faces
+(respectively, @code{nobreak-space} and @code{escape-glyph}) to
+distinguish them from ordinary spaces and hyphens. You can turn off
+this feature by setting the variable @code{nobreak-char-display} to
+@code{nil}. If you set the variable to any other value, that means to
+prefix these characters with an escape character.
@vindex tab-width
+@vindex default-tab-width
Normally, a tab character in the buffer is displayed as whitespace which
extends to the next display tab stop position, and display tab stops come
at intervals equal to eight spaces. The number of spaces per tab is
controlled by the variable @code{tab-width}, which is made local by
-changing it, just like @code{ctl-arrow}. Note that how the tab character
+changing it. Note that how the tab character
in the buffer is displayed has nothing to do with the definition of
@key{TAB} as a command. The variable @code{tab-width} must have an
-integer value between 1 and 1000, inclusive.
-
-@c @vindex truncate-lines @c No index entry here, because we have one
-@c in the continuation section.
- If the variable @code{truncate-lines} is non-@code{nil}, then each
-line of text gets just one screen line for display; if the text line is
-too long, display shows only the part that fits. If
-@code{truncate-lines} is @code{nil}, then long text lines display as
-more than one screen line, enough to show the whole text of the line.
-@xref{Continuation Lines}. Altering the value of @code{truncate-lines}
-makes it local to the current buffer; until that time, the default value
-is in effect. The default is initially @code{nil}.
-
-@c @vindex truncate-partial-width-windows @c Idx entry is in Split Windows.
- If the variable @code{truncate-partial-width-windows} is
-non-@code{nil}, it forces truncation rather than continuation in any
-window less than the full width of the screen or frame, regardless of
-the value of @code{truncate-lines}. For information about side-by-side
-windows, see @ref{Split Window}. See also @ref{Display,, Display,
-elisp, The Emacs Lisp Reference Manual}.
-
-@vindex baud-rate
- The variable @code{baud-rate} holds the output speed of the
-terminal, as far as Emacs knows. Setting this variable does not
-change the speed of actual data transmission, but the value is used
-for calculations. On terminals, it affects padding, and decisions
-about whether to scroll part of the screen or redraw it instead.
-It also affects the behavior of incremental search.
-
- On window-systems, @code{baud-rate} is only used to determine how
-frequently to look for pending input during display updating. A
-higher value of @code{baud-rate} means that check for pending input
-will be done less frequently.
+integer value between 1 and 1000, inclusive. The variable
+@code{default-tab-width} controls the default value of this variable
+for buffers where you have not set it locally.
You can customize the way any particular character code is displayed
by means of a display table. @xref{Display Tables,, Display Tables,
elisp, The Emacs Lisp Reference Manual}.
-@cindex hourglass pointer display
-@vindex hourglass-delay
- On a window system, Emacs can optionally display the mouse pointer
-in a special shape to say that Emacs is busy. To turn this feature on
-or off, customize the group @code{cursor}. You can also control the
-amount of time Emacs must remain busy before the busy indicator is
-displayed, by setting the variable @code{hourglass-delay}.
-
-@findex tty-suppress-bold-inverse-default-colors
- On some text-only terminals, bold face and inverse video together
-result in text that is hard to read. Call the function
-@code{tty-suppress-bold-inverse-default-colors} with a non-@code{nil}
-argument to suppress the effect of bold-face in this case.
-
@node Cursor Display
@section Displaying the Cursor
@findex blink-cursor-mode
+@vindex blink-cursor-alist
@cindex cursor, locating visually
@cindex cursor, blinking
You can customize the cursor's color, and whether it blinks, using
the @code{cursor} Custom group (@pxref{Easy Customization}). On
-graphical terminals, the command @kbd{M-x blink-cursor-mode} enables
+a graphical display, the command @kbd{M-x blink-cursor-mode} enables
or disables the blinking of the cursor. (On text terminals, the
terminal itself blinks the cursor, and Emacs has no control over it.)
+You can control how the cursor appears when it blinks off by setting
+the variable @code{blink-cursor-alist}.
+
+@vindex visible-cursor
+ Some text terminals offer two different cursors: the normal cursor
+and the very visible cursor, where the latter may be e.g. bigger or
+blinking. By default Emacs uses the very visible cursor, and switches
+to it when you start or resume Emacs. If the variable
+@code{visible-cursor} is @code{nil} when Emacs starts or resumes, it
+doesn't switch, so it uses the normal cursor.
@cindex cursor in non-selected windows
@vindex cursor-in-non-selected-windows
Normally, the cursor appears in non-selected windows in the ``off''
state, with the same appearance as when the blinking cursor blinks
-``off''. For a box cursor, this is a hollow box; for a bar cursor,
+``off.'' For a box cursor, this is a hollow box; for a bar cursor,
this is a thinner bar. To turn off cursors in non-selected windows,
-customize the option @code{cursor-in-non-selected-windows} and assign
+customize the variable @code{cursor-in-non-selected-windows} and assign
it a @code{nil} value.
@vindex x-stretch-cursor
@cindex wide block cursor
- On graphical terminals, Emacs can optionally draw the block cursor
+ On graphical displays, Emacs can optionally draw the block cursor
as wide as the character under the cursor---for example, if the cursor
is on a tab character, it would cover the full width occupied by that
tab character. To enable this feature, set the variable
@findex hl-line-mode
@findex global-hl-line-mode
@cindex highlight current line
- If you find it hard to see the cursor, you might like HL Line mode,
-a minor mode that highlights the line containing point. Use @kbd{M-x
+ To make the cursor even more visible, you can use HL Line mode, a
+minor mode that highlights the line containing point. Use @kbd{M-x
hl-line-mode} to enable or disable it in the current buffer. @kbd{M-x
global-hl-line-mode} enables or disables the same mode globally.
+
+@node Line Truncation
+@section Truncation of Lines
+
+@cindex truncation
+@cindex line truncation, and fringes
+ As an alternative to continuation, Emacs can display long lines by
+@dfn{truncation}. This means that all the characters that do not fit
+in the width of the screen or window do not appear at all. On
+graphical displays, a small straight arrow in the fringe indicates
+truncation at either end of the line. On text-only terminals, @samp{$}
+appears in the first column when there is text truncated to the left,
+and in the last column when there is text truncated to the right.
+
+@vindex truncate-lines
+@findex toggle-truncate-lines
+ Horizontal scrolling automatically causes line truncation
+(@pxref{Horizontal Scrolling}). You can explicitly enable line
+truncation for a particular buffer with the command @kbd{M-x
+toggle-truncate-lines}. This works by locally changing the variable
+@code{truncate-lines}. If that variable is non-@code{nil}, long lines
+are truncated; if it is @code{nil}, they are continued onto multiple
+screen lines. Setting the variable @code{truncate-lines} in any way
+makes it local to the current buffer; until that time, the default
+value is in effect. The default value is normally @code{nil}.
+
+@c @vindex truncate-partial-width-windows @c Idx entry is in Split Windows.
+ If the variable @code{truncate-partial-width-windows} is
+non-@code{nil}, it forces truncation rather than continuation in any
+window less than the full width of the screen or frame, regardless of
+the value of @code{truncate-lines}. For information about side-by-side
+windows, see @ref{Split Window}. See also @ref{Display,, Display,
+elisp, The Emacs Lisp Reference Manual}.
+
+@vindex overflow-newline-into-fringe
+ If the variable @code{overflow-newline-into-fringe} is
+non-@code{nil} on a graphical display, then Emacs does not continue or
+truncate a line which is exactly as wide as the window. Instead, the
+newline overflows into the right fringe, and the cursor appears in the
+fringe when positioned on that newline.
+
+@node Display Custom
+@section Customization of Display
+
+ This section describes variables (@pxref{Variables}) that you can
+change to customize how Emacs displays. Beginning users can skip
+it.
+@c the reason for that pxref is because an xref early in the
+@c ``echo area'' section leads here.
+
+@vindex inverse-video
+ If the variable @code{inverse-video} is non-@code{nil}, Emacs attempts
+to invert all the lines of the display from what they normally are.
+
+@vindex visible-bell
+ If the variable @code{visible-bell} is non-@code{nil}, Emacs attempts
+to make the whole screen blink when it would normally make an audible bell
+sound. This variable has no effect if your terminal does not have a way
+to make the screen blink.
+
+@vindex echo-keystrokes
+ The variable @code{echo-keystrokes} controls the echoing of multi-character
+keys; its value is the number of seconds of pause required to cause echoing
+to start, or zero, meaning don't echo at all. The value takes effect when
+there is someting to echo. @xref{Echo Area}.
+
+@vindex baud-rate
+ The variable @anchor{baud-rate}@code{baud-rate} holds the output
+speed of the terminal, as far as Emacs knows. Setting this variable
+does not change the speed of actual data transmission, but the value
+is used for calculations. On text-only terminals, it affects padding,
+and decisions about whether to scroll part of the screen or redraw it
+instead. It also affects the behavior of incremental search.
+
+ On graphical displays, @code{baud-rate} is only used to determine
+how frequently to look for pending input during display updating. A
+higher value of @code{baud-rate} means that check for pending input
+will be done less frequently.
+
+@cindex hourglass pointer display
+@vindex hourglass-delay
+ On graphical display, Emacs can optionally display the mouse pointer
+in a special shape to say that Emacs is busy. To turn this feature on
+or off, customize the group @code{cursor}. You can also control the
+amount of time Emacs must remain busy before the busy indicator is
+displayed, by setting the variable @code{hourglass-delay}.
+
+@vindex overline-margin
+ On graphical display, this variables specifies the vertical position
+of an overline above the text, including the height of the overline
+itself (1 pixel). The default value is 2 pixels.
+
+@vindex x-underline-at-descent-line
+ On graphical display, Emacs normally draws an underline at the
+baseline level of the font. If @code{x-underline-at-descent-line} is
+non-@code{nil}, Emacs draws the underline at the same height as the
+font's descent line.
+
+@findex tty-suppress-bold-inverse-default-colors
+ On some text-only terminals, bold face and inverse video together
+result in text that is hard to read. Call the function
+@code{tty-suppress-bold-inverse-default-colors} with a non-@code{nil}
+argument to suppress the effect of bold-face in this case.
+
+@vindex no-redraw-on-reenter
+ On a text-only terminal, when you reenter Emacs after suspending, Emacs
+normally clears the screen and redraws the entire display. On some
+terminals with more than one page of memory, it is possible to arrange
+the termcap entry so that the @samp{ti} and @samp{te} strings (output
+to the terminal when Emacs is entered and exited, respectively) switch
+between pages of memory so as to use one page for Emacs and another
+page for other output. On such terminals, you might want to set the variable
+@code{no-redraw-on-reenter} non-@code{nil}; this tells Emacs to
+assume, when resumed, that the screen page it is using still contains
+what Emacs last wrote there.
+
+@ignore
+ arch-tag: 2219f910-2ff0-4521-b059-1bd231a536c4
+@end ignore