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(Faces, Font Lock, Highlight Changes)

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(Highlight Interactively, Trailing Whitespace): Moved here from
frames.texi.
(Faces): Changes for new face implementation.
(Font Lock): Remove dscription of M-g M-g since it isn't necessary
with jit-lock being the default.
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Gerd Moellmann 2001-03-05 19:59:46 +00:00
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367
man/display.texi
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@ -1,5 +1,6 @@
@c This is part of the Emacs manual.
@c Copyright (C) 1985, 86, 87, 93, 94, 95, 1997, 2000 Free Software Foundation, Inc.
@c Copyright (C) 1985, 86, 87, 93, 94, 95, 1997, 2000, 2001
@c Free Software Foundation, Inc.
@c See file emacs.texi for copying conditions.
@node Display, Search, Registers, Top
@chapter Controlling the Display
@ -10,6 +11,11 @@ allow you to specify which part of the text you want to see, and how to
display it.
@menu
* Faces:: How to change the display style using 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.
* Trailing Whitespace:: Showing possibly-spurious trailing whitespace.
* Scrolling:: Moving text up and down in a window.
* Horizontal Scrolling:: Moving text left and right in a window.
* Follow Mode:: Follow mode lets two windows scroll as one.
@ -20,6 +26,365 @@ display it.
* Cursor Display:: Features for displaying the cursor.
@end menu
@node Faces
@section Using Multiple Typefaces
@cindex faces
When using Emacs with a window system, you can set up multiple
styles of displaying characters. Some of the aspects of style that
you can control are the type font, the foreground color, the
background color, and whether or not to underline text, and in which
color.
Features which rely on text in multiple faces (such as Font Lock
mode) will also work on non-windowed terminals (including
MS-DOS@pxref{MS-DOS}), that can display more than one face, whether by
colors or underlining and emboldening. This includes the console on
GNU/Linux. Emacs determines automatically whether the terminal has
this capability.
The way you control display style is by defining named @dfn{faces}.
Each face can specify various attributes, like the type font's height,
weight and slant, foreground and background color, and underlining,
but it does not have to specify all of them. By specifying the face
or faces to use for a given part of the text in the buffer, you
control how that text appears.
The style of display used for a given character in the text is
determined by combining several faces. Any aspect of the display
style that isn't specified by overlays or text properties comes from a
default face which inherits its settings from the frame itself.
Enriched mode, the mode for editing formatted text, includes several
commands and menus for specifying faces. @xref{Format Faces}, for how
to specify the font for text in the buffer. @xref{Format Colors}, for
how to specify the foreground and background color.
To alter the appearance of a face, use the customization buffer.
@xref{Face Customization}. You can also use X resources to specify
attributes of particular faces (@pxref{Resources X}).
@cindex face colors, setting
@findex set-face-foreground
@findex set-face-background
Alternatively, you can change the foreground and background colors
of a specific face with @kbd{M-x set-face-foreground} and @kbd{M-x
set-face-background}. These commands prompt in the minibuffer for a
face name and a color name, with completion, and then set that face to
use the specified color.
@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 standardly defined
faces:
@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 mode lines. 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 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 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.
@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 fringe
@cindex fringe
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 frame's border.)
@item scroll-bar
This face determines the visual appearance of the scroll bar.
@item border
This face determines the color of the frame border.
@item cursor
This face determines the color of the 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.
@item tooltip
This face is used for 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.
@item variable-pitch
The basic variable-pitch face.
@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.
@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
@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:
@example
(global-font-lock-mode 1)
@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}.
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:
@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.
@item
Customize the faces interactively with @kbd{M-x customize-face}, as
described in @ref{Face Customization}.
@end itemize
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.
@vindex font-lock-maximum-decoration
The variable @code{font-lock-maximum-decoration} specifies the
preferred level of fontification, for modes that provide multiple
levels. Level 1 is the least amount of fontification; some modes
support levels as high as 3. The normal default is ``as high as
possible.'' You can specify an integer, which applies to all modes, or
you can specify different numbers for particular major modes; for
example, to use level 1 for C/C++ modes, and the default level
otherwise, use this:
@example
(setq font-lock-maximum-decoration
'((c-mode . 1) (c++-mode . 1)))
@end example
@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.
@c @w is used below to prevent a bad page-break.
@vindex font-lock-beginning-of-syntax-function
Comment and string fontification (or ``syntactic'' fontification)
relies on analysis of the syntactic structure of the buffer text. For
the purposes of speed, some modes including C mode and Lisp mode rely on
a special convention: an open-parenthesis in the leftmost column always
defines the @w{beginning} of a defun, and is thus always outside any string
or comment. (@xref{Defuns}.) If you don't follow this convention,
then Font Lock mode can misfontify the text after an open-parenthesis in
the leftmost column that is inside a string or comment.
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.
@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
@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 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 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 Trailing Whitespace
@section Trailing Whitespace
@cindex trailing whitespace
@cindex whitespace, trailing
@vindex show-trailing-whitespace
It is easy to leave unnecessary spaces at the end of a line without
realizing it. In most cases, this @dfn{trailing whitespace} has no
effect, but there are special circumstances where it matters.
You can make trailing whitespace visible on the screen by setting
the variable @code{show-trailing-whitespace} to @code{t}. Then Emacs
displays trailing whitespace in the face @code{trailing-whitespace}.
Trailing whitespace is defined as spaces or tabs at the end of a
line. But trailing whitespace is not displayed specially if point is
at the end of the line containing the whitespace. (Doing that looks
ugly while you are typing in new text, and the location of point is
enough in that case to show you that the spaces are present.)
@vindex indicate-empty-lines
@vindex default-indicate-empty-lines
@cindex empty lines
Emacs can indicate empty lines at the end of the buffer with a
special bitmap on 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.
@node Scrolling
@section Scrolling