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1260 lines
56 KiB
Plaintext
1260 lines
56 KiB
Plaintext
@c This is part of the Emacs manual.
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@c Copyright (C) 1985, 1986, 1987, 1993, 1994, 1995, 1997, 2000, 2001,
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@c 2002, 2003, 2004, 2005, 2006, 2007 Free Software Foundation, Inc.
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@c See file emacs.texi for copying conditions.
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@node Display, Search, Registers, Top
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@chapter Controlling the Display
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Since only part of a large buffer fits in the window, Emacs tries to
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show a part that is likely to be interesting. Display-control
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commands allow you to specify which part of the text you want to see,
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and how to display it. Many variables also affect the details of
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redisplay. Unless otherwise stated, the variables described in this
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chapter have their effect by customizing redisplay itself; therefore,
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their values only make a difference at the time of redisplay.
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@menu
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* Scrolling:: Commands to move text up and down in a window.
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* Auto Scrolling:: Redisplay scrolls text automatically when needed.
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* Horizontal Scrolling:: Moving text left and right in a window.
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* Follow Mode:: Follow mode lets two windows scroll as one.
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* Faces:: How to change the display style using faces.
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* Standard Faces:: Emacs' predefined faces.
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* Font Lock:: Minor mode for syntactic highlighting using faces.
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* Highlight Interactively:: Tell Emacs what text to highlight.
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* Fringes:: Enabling or disabling window fringes.
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* Displaying Boundaries:: Displaying top and bottom of the buffer.
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* Useless Whitespace:: Showing possibly-spurious trailing whitespace.
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* Selective Display:: Hiding lines with lots of indentation.
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* Optional Mode Line:: Optional mode line display features.
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* Text Display:: How text characters are normally displayed.
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* Cursor Display:: Features for displaying the cursor.
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* Line Truncation:: Truncating lines to fit the screen width instead
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of continuing them to multiple screen lines.
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* Display Custom:: Information on variables for customizing display.
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@end menu
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@node Scrolling
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@section Scrolling
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If a buffer contains text that is too large to fit entirely within a
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window that is displaying the buffer, Emacs shows a contiguous portion of
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the text. The portion shown always contains point.
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@cindex scrolling
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@dfn{Scrolling} means moving text up or down in the window so that
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different parts of the text are visible. Scrolling ``forward'' or
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``up'' means that text moves up, and new text appears at the bottom.
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Scrolling ``backward'' or ``down'' moves text down, and new text
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appears at the top.
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Scrolling happens automatically if you move point past the bottom or
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top of the window. You can also scroll explicitly with the commands
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in this section.
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@table @kbd
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@item C-l
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Clear screen and redisplay, scrolling the selected window to center
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point vertically within it (@code{recenter}).
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@item C-v
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Scroll forward (a windowful or a specified number of lines) (@code{scroll-up}).
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@item @key{NEXT}
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@itemx @key{PAGEDOWN}
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Likewise, scroll forward.
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@item M-v
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Scroll backward (@code{scroll-down}).
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@item @key{PRIOR}
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@itemx @key{PAGEUP}
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Likewise, scroll backward.
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@item @var{arg} C-l
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Scroll so point is on line @var{arg} (@code{recenter}).
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@item C-M-l
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Scroll heuristically to bring useful information onto the screen
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(@code{reposition-window}).
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@end table
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@kindex C-l
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@findex recenter
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The most basic scrolling command is @kbd{C-l} (@code{recenter}) with
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no argument. It scrolls the selected window so that point is halfway
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down from the top of the window. On a text terminal, it also clears
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the screen and redisplays all windows. That is useful in case the
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screen is garbled (@pxref{Screen Garbled}).
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@kindex C-v
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@kindex M-v
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@kindex NEXT
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@kindex PRIOR
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@kindex PAGEDOWN
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@kindex PAGEUP
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@findex scroll-up
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@findex scroll-down
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To read the buffer a windowful at a time, use @kbd{C-v}
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(@code{scroll-up}) with no argument. This scrolls forward by nearly
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the whole window height. The effect is to take the two lines at the
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bottom of the window and put them at the top, followed by nearly a
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whole windowful of lines that were not previously visible. If point
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was in the text that scrolled off the top, it ends up at the new top
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of the window.
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@vindex next-screen-context-lines
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@kbd{M-v} (@code{scroll-down}) with no argument scrolls backward in
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a similar way, also with overlap. The number of lines of overlap that
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the @kbd{C-v} or @kbd{M-v} commands leave is controlled by the
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variable @code{next-screen-context-lines}; by default, it is 2. The
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function keys @key{NEXT} and @key{PRIOR}, or @key{PAGEDOWN} and
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@key{PAGEUP}, are equivalent to @kbd{C-v} and @kbd{M-v}.
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The commands @kbd{C-v} and @kbd{M-v} with a numeric argument scroll
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the text in the selected window up or down a few lines. @kbd{C-v}
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with an argument moves the text and point up, together, that many
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lines; it brings the same number of new lines into view at the bottom
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of the window. @kbd{M-v} with numeric argument scrolls the text
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downward, bringing that many new lines into view at the top of the
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window. @kbd{C-v} with a negative argument is like @kbd{M-v} and vice
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versa.
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The names of scroll commands are based on the direction that the
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text moves in the window. Thus, the command to scroll forward is
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called @code{scroll-up} because it moves the text upward on the
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screen. The keys @key{PAGEDOWN} and @key{PAGEUP} derive their names
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and customary meanings from a different convention that developed
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elsewhere; hence the strange result that @key{PAGEDOWN} runs
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@code{scroll-up}.
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@vindex scroll-preserve-screen-position
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Some users like the full-screen scroll commands to keep point at the
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same screen line. To enable this behavior, set the variable
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@code{scroll-preserve-screen-position} to a non-@code{nil} value. In
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this mode, when these commands would scroll the text around point off
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the screen, or within @code{scroll-margin} lines of the edge, they
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move point to keep the same vertical position within the window.
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This mode is convenient for browsing through a file by scrolling by
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screenfuls; if you come back to the screen where you started, point
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goes back to the line where it started. However, this mode is
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inconvenient when you move to the next screen in order to move point
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to the text there.
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Another way to do scrolling is with @kbd{C-l} with a numeric argument.
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@kbd{C-l} does not clear the screen when given an argument; it only scrolls
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the selected window. With a positive argument @var{n}, it repositions text
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to put point @var{n} lines down from the top. An argument of zero puts
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point on the very top line. Point does not move with respect to the text;
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rather, the text and point move rigidly on the screen. @kbd{C-l} with a
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negative argument puts point that many lines from the bottom of the window.
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For example, @kbd{C-u - 1 C-l} puts point on the bottom line, and @kbd{C-u
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- 5 C-l} puts it five lines from the bottom. @kbd{C-u C-l} scrolls to put
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point at the center (vertically) of the selected window.
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@kindex C-M-l
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@findex reposition-window
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The @kbd{C-M-l} command (@code{reposition-window}) scrolls the current
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window heuristically in a way designed to get useful information onto
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the screen. For example, in a Lisp file, this command tries to get the
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entire current defun onto the screen if possible.
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@node Auto Scrolling
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@section Automatic Scrolling
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@vindex scroll-conservatively
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Redisplay scrolls the buffer automatically when point moves out of
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the visible portion of the text. The purpose of automatic scrolling
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is to make point visible, but you can customize many aspects of how
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this is done.
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Normally, automatic scrolling centers point vertically within the
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window. However, if you set @code{scroll-conservatively} to a small
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number @var{n}, then if you move point just a little off the
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screen---less than @var{n} lines---then Emacs scrolls the text just
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far enough to bring point back on screen. By default,
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@code{scroll-conservatively} is@tie{}0.
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@cindex aggressive scrolling
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@vindex scroll-up-aggressively
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@vindex scroll-down-aggressively
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When the window does scroll by a longer distance, you can control
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how aggressively it scrolls, by setting the variables
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@code{scroll-up-aggressively} and @code{scroll-down-aggressively}.
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The value of @code{scroll-up-aggressively} should be either
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@code{nil}, or a fraction @var{f} between 0 and 1. A fraction
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specifies where on the screen to put point when scrolling upward.
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More precisely, when a window scrolls up because point is above the
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window start, the new start position is chosen to put point @var{f}
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part of the window height from the top. The larger @var{f}, the more
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aggressive the scrolling.
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@code{nil}, which is the default, scrolls to put point at the center.
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So it is equivalent to .5.
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Likewise, @code{scroll-down-aggressively} is used for scrolling
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down. The value, @var{f}, specifies how far point should be placed
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from the bottom of the window; thus, as with
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@code{scroll-up-aggressively}, a larger value is more aggressive.
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@vindex scroll-margin
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The variable @code{scroll-margin} restricts how close point can come
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to the top or bottom of a window. Its value is a number of screen
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lines; if point comes within that many lines of the top or bottom of the
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window, Emacs recenters the window. By default, @code{scroll-margin} is
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0.
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@node Horizontal Scrolling
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@section Horizontal Scrolling
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@cindex horizontal scrolling
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@dfn{Horizontal scrolling} means shifting all the lines sideways
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within a window---so that some of the text near the left margin is not
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displayed at all. When the text in a window is scrolled horizontally,
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text lines are truncated rather than continued (@pxref{Line
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Truncation}). Whenever a window shows truncated lines, Emacs
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automatically updates its horizontal scrolling whenever point moves
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off the left or right edge of the screen. You can also use these
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commands to do explicit horizontal scrolling.
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@table @kbd
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@item C-x <
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Scroll text in current window to the left (@code{scroll-left}).
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@item C-x >
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Scroll to the right (@code{scroll-right}).
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@end table
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@kindex C-x <
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@kindex C-x >
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@findex scroll-left
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@findex scroll-right
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The command @kbd{C-x <} (@code{scroll-left}) scrolls the selected
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window to the left by @var{n} columns with argument @var{n}. This moves
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part of the beginning of each line off the left edge of the window.
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With no argument, it scrolls by almost the full width of the window (two
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columns less, to be precise).
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@kbd{C-x >} (@code{scroll-right}) scrolls similarly to the right. The
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window cannot be scrolled any farther to the right once it is displayed
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normally (with each line starting at the window's left margin);
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attempting to do so has no effect. This means that you don't have to
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calculate the argument precisely for @w{@kbd{C-x >}}; any sufficiently large
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argument will restore the normal display.
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If you use those commands to scroll a window horizontally, that sets
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a lower bound for automatic horizontal scrolling. Automatic scrolling
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will continue to scroll the window, but never farther to the right
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than the amount you previously set by @code{scroll-left}.
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@vindex hscroll-margin
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The value of the variable @code{hscroll-margin} controls how close
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to the window's edges point is allowed to get before the window will
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be automatically scrolled. It is measured in columns. If the value
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is 5, then moving point within 5 columns of the edge causes horizontal
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scrolling away from that edge.
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@vindex hscroll-step
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The variable @code{hscroll-step} determines how many columns to
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scroll the window when point gets too close to the edge. If it's
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zero, horizontal scrolling centers point horizontally within the
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window. If it's a positive integer, it specifies the number of
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columns to scroll by. If it's a floating-point number, it specifies
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the fraction of the window's width to scroll by. The default is zero.
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@vindex auto-hscroll-mode
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To disable automatic horizontal scrolling, set the variable
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@code{auto-hscroll-mode} to @code{nil}.
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@node Follow Mode
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@section Follow Mode
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@cindex Follow mode
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@cindex mode, Follow
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@findex follow-mode
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@cindex windows, synchronizing
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@cindex synchronizing windows
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@dfn{Follow mode} is a minor mode that makes two windows, both
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showing the same buffer, scroll as a single tall ``virtual window.''
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To use Follow mode, go to a frame with just one window, split it into
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two side-by-side windows using @kbd{C-x 3}, and then type @kbd{M-x
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follow-mode}. From then on, you can edit the buffer in either of the
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two windows, or scroll either one; the other window follows it.
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In Follow mode, if you move point outside the portion visible in one
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window and into the portion visible in the other window, that selects
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the other window---again, treating the two as if they were parts of
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one large window.
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To turn off Follow mode, type @kbd{M-x follow-mode} a second time.
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@node Faces
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@section Using Multiple Typefaces
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@cindex faces
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You can specify various styles for displaying text using
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@dfn{faces}. Each face can specify various @dfn{face attributes},
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such as the font family, the height, weight and slant of the
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characters, the foreground and background color, and underlining or
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overlining. A face does not have to specify all of these attributes;
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often it inherits most of them from another face.
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On graphical display, all the Emacs face attributes are meaningful.
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On a text-only terminal, only some of them work. Some text-only
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terminals support inverse video, bold, and underline attributes; some
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support colors. Text-only terminals generally do not support changing
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the height and width or the font family.
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Emacs uses faces automatically for highlighting, through the work of
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Font Lock mode. @xref{Font Lock}, for more information about Font
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Lock mode and syntactic highlighting. You can print out the buffer
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with the highlighting that appears on your screen using the command
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@code{ps-print-buffer-with-faces}. @xref{PostScript}.
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You control the appearance of a part of the text in the buffer by
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specifying the face or faces to use for it. The style of display used
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for any given character is determined by combining the attributes of
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all the applicable faces specified for that character. Any attribute
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that isn't specified by these faces is taken from the @code{default} face,
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whose attributes reflect the default settings of the frame itself.
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Enriched mode, the mode for editing formatted text, includes several
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commands and menus for specifying faces for text in the buffer.
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@xref{Format Faces}, for how to specify the font for text in the
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buffer. @xref{Format Colors}, for how to specify the foreground and
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background color.
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@cindex face colors, setting
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@findex set-face-foreground
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@findex set-face-background
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To alter the appearance of a face, use the customization buffer.
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@xref{Face Customization}. You can also use X resources to specify
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attributes of particular faces (@pxref{Resources}). Alternatively,
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you can change the foreground and background colors of a specific face
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with @kbd{M-x set-face-foreground} and @kbd{M-x set-face-background}.
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These commands prompt in the minibuffer for a face name and a color
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name, with completion, and then set that face to use the specified
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color. Changing the colors of the @code{default} face also changes
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the foreground and background colors on all frames, both existing and
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those to be created in the future. (You can also set foreground and
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background colors for the current frame only; see @ref{Frame
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Parameters}.)
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If you want to alter the appearance of all Emacs frames, you need to
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customize the frame parameters in the variable
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@code{default-frame-alist}; see @ref{Creating Frames,
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default-frame-alist}.
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Emacs can correctly display variable-width fonts, but Emacs commands
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that calculate width and indentation do not know how to calculate
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variable widths. This can sometimes lead to incorrect results when
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you use variable-width fonts. In particular, indentation commands can
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give inconsistent results, so we recommend you avoid variable-width
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fonts for editing program source code. Filling will sometimes make
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lines too long or too short. We plan to address these issues in
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future Emacs versions.
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@node Standard Faces
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@section Standard Faces
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@findex list-faces-display
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To see what faces are currently defined, and what they look like,
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type @kbd{M-x list-faces-display}. It's possible for a given face to
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look different in different frames; this command shows the appearance
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in the frame in which you type it. With a prefix argument, this
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prompts for a regular expression, and displays only faces with names
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matching that regular expression.
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Here are the standard faces for specifying text appearance. You can
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apply them to specific text when you want the effects they produce.
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@table @code
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@item default
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This face is used for ordinary text that doesn't specify any face.
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@item bold
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This face uses a bold variant of the default font, if it has one.
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It's up to you to choose a default font that has a bold variant,
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if you want to use one.
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@item italic
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This face uses an italic variant of the default font, if it has one.
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@item bold-italic
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This face uses a bold italic variant of the default font, if it has one.
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@item underline
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This face underlines text.
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@item fixed-pitch
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This face forces use of a particular fixed-width font.
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@item variable-pitch
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This face forces use of a particular variable-width font. It's
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reasonable to customize this face to use a different variable-width font,
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if you like, but you should not make it a fixed-width font.
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@item shadow
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This face is used for making the text less noticeable than the surrounding
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ordinary text. Usually this can be achieved by using shades of gray in
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contrast with either black or white default foreground color.
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@end table
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Here's an incomplete list of faces used to highlight parts of the
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text temporarily for specific purposes. (Many other modes define
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their own faces for this purpose.)
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@table @code
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@item highlight
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This face is used for highlighting portions of text, in various modes.
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For example, mouse-sensitive text is highlighted using this face.
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@item isearch
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This face is used for highlighting the current Isearch match.
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@item query-replace
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This face is used for highlighting the current Query Replace match.
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@item lazy-highlight
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This face is used for lazy highlighting of Isearch and Query Replace
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matches other than the current one.
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@item region
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This face is used for displaying a selected region (when Transient Mark
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mode is enabled---see below).
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@item secondary-selection
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This face is used for displaying a secondary X selection (@pxref{Secondary
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Selection}).
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@item trailing-whitespace
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The face for highlighting excess spaces and tabs at the end of a line
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when @code{show-trailing-whitespace} is non-@code{nil}; see
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@ref{Useless Whitespace}.
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@item nobreak-space
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The face for displaying the character ``nobreak space.''
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@item escape-glyph
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The face for highlighting the @samp{\} or @samp{^} that indicates
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a control character. It's also used when @samp{\} indicates a
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nobreak space or nobreak (soft) hyphen.
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@end table
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@cindex @code{region} face
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When Transient Mark mode is enabled, the text of the region is
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highlighted when the mark is active. This uses the face named
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@code{region}; you can control the style of highlighting by changing the
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style of this face (@pxref{Face Customization}). @xref{Transient Mark},
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for more information about Transient Mark mode and activation and
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deactivation of the mark.
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These faces control the appearance of parts of the Emacs frame.
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They exist as faces to provide a consistent way to customize the
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appearance of these parts of the frame.
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@table @code
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@item mode-line
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@itemx modeline
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This face is used for the mode line of the currently selected window,
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and for menu bars when toolkit menus are not used. By default, it's
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drawn with shadows for a ``raised'' effect on graphical displays, and
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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 @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
|
|
This face determines the color of the cursor.
|
|
@item mouse
|
|
This face determines the color of the mouse pointer.
|
|
@item tool-bar
|
|
This face determines the color of tool bar icons. @xref{Tool Bars}.
|
|
@item tooltip
|
|
This face is used for tooltips. @xref{Tooltips}.
|
|
@item menu
|
|
@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
|
|
|
|
@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'') 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
|
|
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
|
|
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 0)
|
|
@end example
|
|
|
|
@noindent
|
|
This variable, like all the variables that control Font Lock mode,
|
|
take effect whenever fontification is done; that is, potentially at
|
|
any time.
|
|
|
|
@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:
|
|
|
|
@example
|
|
(add-hook 'c-mode-hook 'turn-on-font-lock)
|
|
@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 @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}.
|
|
|
|
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
|
|
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 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 incorrect fontification
|
|
@cindex parenthesis in column zero and fontification
|
|
@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 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}. @xref{Search-based
|
|
Fontification,,, elisp, The Emacs Lisp Reference Manual}, for
|
|
documentation of the format of this list.
|
|
|
|
@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 Highlight Interactively
|
|
@section Interactive Highlighting
|
|
@cindex highlighting by matching
|
|
@cindex interactive highlighting
|
|
@cindex Highlight Changes mode
|
|
|
|
@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.
|
|
|
|
@cindex Hi Lock mode
|
|
@findex hi-lock-mode
|
|
Hi Lock mode highlights text that matches regular expressions you
|
|
specify. 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 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.
|
|
|
|
@item C-x w r @var{regexp} @key{RET}
|
|
@kindex C-x w r
|
|
@findex unhighlight-regexp
|
|
Unhighlight @var{regexp} (@code{unhighlight-regexp}).
|
|
|
|
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.
|
|
|
|
@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 are extracted from the comments, if appropriate, if you
|
|
invoke @kbd{M-x hi-lock-find-patterns}, or if you visit the file while
|
|
Hi Lock mode is enabled (since that runs @code{hi-lock-find-patterns}).
|
|
|
|
@item C-x w i
|
|
@kindex C-x w i
|
|
@findex hi-lock-find-patterns
|
|
Extract regexp/face pairs from comments in the current buffer
|
|
(@code{hi-lock-find-patterns}). Thus, you can enter patterns
|
|
interactively with @code{highlight-regexp}, store them into the file
|
|
with @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-find-patterns}) to
|
|
have Hi Lock highlight the edited patterns.
|
|
|
|
@vindex hi-lock-file-patterns-policy
|
|
The variable @code{hi-lock-file-patterns-policy} controls whether Hi
|
|
Lock mode should automatically extract and highlight patterns found in
|
|
a file when it is visited. Its value can be @code{nil} (never
|
|
highlight), @code{t} (highlight the patterns), @code{ask} (query the
|
|
user), or a function. If it is a function,
|
|
@code{hi-lock-find-patterns} calls it with the patterns as argument;
|
|
if the function returns non-@code{nil}, the patterns are used. The
|
|
default is @code{nil}. Note that patterns are always highlighted if
|
|
you call @code{hi-lock-find-patterns} directly, regardless of the
|
|
value of this variable.
|
|
|
|
@vindex hi-lock-exclude-modes
|
|
Also, @code{hi-lock-find-patterns} 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
|
|
@cindex fringes
|
|
|
|
On a graphical display, each Emacs window normally has narrow
|
|
@dfn{fringes} on the left and right edges. The fringes display
|
|
indications about the text in the window.
|
|
|
|
The most common use of the fringes is to indicate a continuation
|
|
line, when one line of text is split into multiple lines on the
|
|
screen. The left fringe shows a curving arrow for each screen line
|
|
except the first, indicating that ``this is not the real beginning.''
|
|
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 horizontal arrows
|
|
meaning ``there's more text on this line which is scrolled
|
|
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
|
|
You can enable and disable the fringes for all frames using
|
|
@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
|
|
|
|
@cindex trailing whitespace
|
|
@cindex whitespace, trailing
|
|
@vindex show-trailing-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. 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
|
|
@code{show-trailing-whitespace} to @code{t}. Then Emacs displays
|
|
trailing whitespace in the face @code{trailing-whitespace}.
|
|
|
|
This feature does not apply when point is at the end of the line
|
|
containing the whitespace. Strictly speaking, that is ``trailing
|
|
whitespace'' nonetheless, but displaying it specially in that case
|
|
looks ugly while you are typing in new text. In this special case,
|
|
the location of point is enough to show you that the spaces are
|
|
present.
|
|
|
|
@findex delete-trailing-whitespace
|
|
To delete all trailing whitespace within the current buffer's
|
|
accessible portion (@pxref{Narrowing}), type @kbd{M-x
|
|
delete-trailing-whitespace @key{RET}}. (This command does not remove
|
|
the form-feed characters.)
|
|
|
|
@vindex indicate-empty-lines
|
|
@vindex default-indicate-empty-lines
|
|
@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
|
|
@cindex selective display
|
|
@findex set-selective-display
|
|
@kindex C-x $
|
|
|
|
Emacs has the ability to hide lines indented more than a certain number
|
|
of columns (you specify how many columns). You can use this to get an
|
|
overview of a part of a program.
|
|
|
|
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.
|
|
|
|
The hidden lines are still present in the buffer, and most editing
|
|
commands see them as usual, so you may find point in the middle of the
|
|
hidden text. When this happens, the cursor appears at the end of the
|
|
previous line, after the three dots. If point is at the end of the
|
|
visible line, before the newline that ends it, the cursor appears before
|
|
the three dots.
|
|
|
|
To make all lines visible again, type @kbd{C-x $} with no argument.
|
|
|
|
@vindex selective-display-ellipses
|
|
If you set the variable @code{selective-display-ellipses} to
|
|
@code{nil}, the three dots do not appear at the end of a line that
|
|
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
|
|
after the buffer percentage @var{pos}, with the letter @samp{L} to
|
|
indicate what it is.
|
|
|
|
@cindex Column Number mode
|
|
@cindex mode, Column Number
|
|
@findex column-number-mode
|
|
Similarly, you can display the current column number by turning on
|
|
Column number mode with @kbd{M-x column-number-mode}. The column
|
|
number is indicated by the letter @samp{C}. However, when both of
|
|
these modes are enabled, the line and column numbers are displayed in
|
|
parentheses, the line number first, rather than with @samp{L} and
|
|
@samp{C}. For example: @samp{(561,2)}. @xref{Minor Modes}, for more
|
|
information about minor modes and about how to use these commands.
|
|
|
|
@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
|
|
@code{line-number-display-limit}), then the line number doesn't appear.
|
|
Emacs doesn't compute the line number when the buffer is large, because
|
|
that would be too slow. Set it to @code{nil} to remove the limit.
|
|
|
|
@vindex line-number-display-limit-width
|
|
Line-number computation can also be slow if the lines in the buffer
|
|
are too long. For this reason, Emacs normally doesn't display line
|
|
numbers if the average width, in characters, of lines near point is
|
|
larger than the value of the variable
|
|
@code{line-number-display-limit-width}. The default value is 200
|
|
characters.
|
|
|
|
@findex display-time
|
|
@cindex time (on mode line)
|
|
Emacs can optionally display the time and system load in all mode
|
|
lines. To enable this feature, type @kbd{M-x display-time} or customize
|
|
the option @code{display-time-mode}. The information added to the mode
|
|
line usually appears after the buffer name, before the mode names and
|
|
their parentheses. It looks like this:
|
|
|
|
@example
|
|
@var{hh}:@var{mm}pm @var{l.ll}
|
|
@end example
|
|
|
|
@noindent
|
|
@vindex display-time-24hr-format
|
|
Here @var{hh} and @var{mm} are the hour and minute, followed always by
|
|
@samp{am} or @samp{pm}. @var{l.ll} is the average number of running
|
|
processes in the whole system recently. (Some fields may be missing if
|
|
your operating system cannot support them.) If you prefer time display
|
|
in 24-hour format, set the variable @code{display-time-24hr-format}
|
|
to @code{t}.
|
|
|
|
@cindex mail (on mode line)
|
|
@vindex display-time-use-mail-icon
|
|
@vindex display-time-mail-face
|
|
@vindex display-time-mail-file
|
|
@vindex display-time-mail-directory
|
|
The word @samp{Mail} appears after the load level if there is mail
|
|
for you that you have not read yet. On a graphical display you can use
|
|
an icon instead of @samp{Mail} by customizing
|
|
@code{display-time-use-mail-icon}; this may save some space on the mode
|
|
line. You can customize @code{display-time-mail-face} to make the mail
|
|
indicator prominent. Use @code{display-time-mail-file} to specify
|
|
the mail file to check, or set @code{display-time-mail-directory}
|
|
to specify the directory to check for incoming mail (any nonempty regular
|
|
file in the directory is considered as ``newly arrived mail'').
|
|
|
|
@cindex mode line, 3D appearance
|
|
@cindex attributes of mode line, changing
|
|
@cindex non-integral number of lines in a window
|
|
By default, the mode line is drawn on graphics displays with
|
|
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. @xref{Face Customization}.
|
|
|
|
@cindex non-selected windows, mode line appearance
|
|
By default, the mode line of nonselected windows is displayed in a
|
|
different face, called @code{mode-line-inactive}. Only the selected
|
|
window is displayed in the @code{mode-line} face. This helps show
|
|
which window is selected. When the minibuffer is selected, since
|
|
it has no mode line, the window from which you activated the minibuffer
|
|
has its mode line displayed using @code{mode-line}; as a result,
|
|
ordinary entry to the minibuffer does not change any mode lines.
|
|
|
|
@vindex mode-line-in-non-selected-windows
|
|
You can disable use of @code{mode-line-inactive} by setting variable
|
|
@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)
|
|
|
|
@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 @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 @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}. The caret appears in face
|
|
@code{escape-glyph}.
|
|
|
|
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}, 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}.
|
|
|
|
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. 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. 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}.
|
|
|
|
@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
|
|
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,
|
|
this is a thinner bar. To turn off cursors in non-selected windows,
|
|
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 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
|
|
@code{x-stretch-cursor} to a non-@code{nil} value.
|
|
|
|
@findex hl-line-mode
|
|
@findex global-hl-line-mode
|
|
@cindex highlight current line
|
|
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
|