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(Refresh Screen, Forcing Redisplay):

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Clarify the text and move items around.
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Richard M. Stallman 2007-11-24 15:40:39 +00:00
parent 75a79fb387
commit 20c63e44d1
2 changed files with 54 additions and 31 deletions
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lispref/ChangeLog
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@ -1,3 +1,8 @@
2007-11-24 Richard Stallman <rms@gnu.org>
* display.texi (Refresh Screen, Forcing Redisplay):
Clarify the text and move items around.
2007-11-15 Martin Rudalics <rudalics@gmx.at>
* vol1.texi (Top): Remove Frame-Local Variables from Node Listing.

80
lispref/display.texi
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@ -55,21 +55,10 @@ This function clears and redisplays frame @var{frame}.
This function clears and redisplays all visible frames.
@end deffn
This function calls for redisplay of certain windows, the next time
redisplay is done, but does not clear them first.
@defun force-window-update &optional object
This function forces some or all windows to be updated on next redisplay.
If @var{object} is a window, it forces redisplay of that window. If
@var{object} is a buffer or buffer name, it forces redisplay of all
windows displaying that buffer. If @var{object} is @code{nil} (or
omitted), it forces redisplay of all windows.
@end defun
Processing user input takes absolute priority over redisplay. If you
call these functions when input is available, they do nothing
immediately, but a full redisplay does happen eventually---after all the
input has been processed.
In Emacs, processing user input takes priority over redisplay. If
you call these functions when input is available, they don't redisplay
immediately, but the requested redisplay does happen
eventually---after all the input has been processed.
Normally, suspending and resuming Emacs also refreshes the screen.
Some terminal emulators record separate contents for display-oriented
@ -89,11 +78,56 @@ to redraw, @code{nil} means redrawing is needed. The default is @code{nil}.
@section Forcing Redisplay
@cindex forcing redisplay
Emacs normally tries to redisplay the screen whenever it waits for
input. With this function you can request an immediate attempt to
redisplay, in the middle of Lisp code, without actually waiting for
input.
@defun redisplay &optional force
This function tries immediately to redisplay, provided there are no
pending input events. It is equivalent to @code{(sit-for 0)}.
If the optional argument @var{force} is non-@code{nil}, it does all
pending redisplay work even if input is available, with no
pre-emption.
The function returns @code{t} if it actually tried to redisplay, and
@code{nil} otherwise. A value of @code{t} does not mean that
redisplay proceeded to completion; it could have been pre-empted by
newly arriving terminal input.
@end defun
@code{redisplay} with no argument tries immediately to redisplay,
but has no effect on the usual rules for what parts of the screen to
redisplay. By contrast, the following function adds certain windows
to the pending redisplay work (as if their contents had completely
changed), but doesn't immediately try to do any redisplay work.
@defun force-window-update &optional object
This function forces some or all windows to be updated on next
redisplay. If @var{object} is a window, it requires eventual
redisplay of that window. If @var{object} is a buffer or buffer name,
it requires eventual redisplay of all windows displaying that buffer.
If @var{object} is @code{nil} (or omitted), it requires eventual
redisplay of all windows.
@end defun
@code{force-window-update} does not do a redisplay immediately.
(Emacs will do that when it waits for input.) Rather, its effect is
to put more work on the queue to be done by redisplay whenever there
is a chance.
Emacs redisplay normally stops if input arrives, and does not happen
at all if input is available before it starts. Most of the time, this
is exactly what you want. However, you can prevent preemption by
binding @code{redisplay-dont-pause} to a non-@code{nil} value.
@defvar redisplay-dont-pause
If this variable is non-@code{nil}, pending input does not
prevent or halt redisplay; redisplay occurs, and finishes,
regardless of whether input is available.
@end defvar
@defvar redisplay-preemption-period
This variable specifies how many seconds Emacs waits between checks
for new input during redisplay. (The default is 0.1 seconds.) If
@ -107,22 +141,6 @@ This variable is only obeyed on graphical terminals. For
text terminals, see @ref{Terminal Output}.
@end defvar
@defvar redisplay-dont-pause
If this variable is non-@code{nil}, pending input does not
prevent or halt redisplay; redisplay occurs, and finishes,
regardless of whether input is available.
@end defvar
@defun redisplay &optional force
This function performs an immediate redisplay provided there are no
pending input events. This is equivalent to @code{(sit-for 0)}.
If the optional argument @var{force} is non-@code{nil}, it forces an
immediate and complete redisplay even if input is available.
Returns @code{t} if redisplay was performed, or @code{nil} otherwise.
@end defun
@node Truncation
@section Truncation
@cindex line wrapping