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Textual scrolling means moving the text up or down through a window.
It works by changing the value of the window's display-start location. It
may also change the value of window-point to keep point on the
screen.
Textual scrolling was formerly called “vertical scrolling,” but we changed its name to distinguish it from the new vertical fractional scrolling feature (voir la section Vertical Fractional Scrolling).
In the commands scroll-up and scroll-down, the directions
“up” and “down” refer to the motion of the text in the buffer at which
you are looking through the window. Imagine that the text is written on a
long roll of paper and that the scrolling commands move the paper up and
down. Thus, if you are looking at text in the middle of a buffer and
repeatedly call scroll-down, you will eventually see the beginning of
the buffer.
Some people have urged that the opposite convention be used: they imagine that the window moves over text that remains in place. Then “down” commands would take you to the end of the buffer. This view is more consistent with the actual relationship between windows and the text in the buffer, but it is less like what the user sees. The position of a window on the terminal does not move, and short scrolling commands clearly move the text up or down on the screen. We have chosen names that fit the user's point of view.
The textual scrolling functions (aside from scroll-other-window) have
unpredictable results if the current buffer is different from the buffer
that is displayed in the selected window. Voir la section The Current Buffer.
If the window contains a row which is taller than the height of the window
(for example in the presence of a large image), the scroll functions will
adjust the window vscroll to scroll the partially visible row. To disable
this feature, Lisp code may bind the variable `auto-window-vscroll' to
nil (voir la section Vertical Fractional Scrolling).
This function scrolls the text in the selected window upward count lines. If count is negative, scrolling is actually downward.
If count is nil (or omitted), then the length of scroll is
next-screen-context-lines lines less than the usable height of the
window (not counting its mode line).
scroll-up returns nil, unless it gets an error because it
can't scroll any further.
This function scrolls the text in the selected window downward count lines. If count is negative, scrolling is actually upward.
If count is omitted or nil, then the length of the scroll is
next-screen-context-lines lines less than the usable height of the
window (not counting its mode line).
scroll-down returns nil, unless it gets an error because it
can't scroll any further.
This function scrolls the text in another window upward count lines.
Negative values of count, or nil, are handled as in
scroll-up.
You can specify which buffer to scroll by setting the variable
other-window-scroll-buffer to a buffer. If that buffer isn't already
displayed, scroll-other-window displays it in some window.
When the selected window is the minibuffer, the next window is normally the
one at the top left corner. You can specify a different window to scroll,
when the minibuffer is selected, by setting the variable
minibuffer-scroll-window. This variable has no effect when any other
window is selected. When it is non-nil and the minibuffer is
selected, it takes precedence over other-window-scroll-buffer.
Voir Definition of minibuffer-scroll-window.
When the minibuffer is active, it is the next window if the selected window
is the one at the bottom right corner. In this case,
scroll-other-window attempts to scroll the minibuffer. If the
minibuffer contains just one line, it has nowhere to scroll to, so the line
reappears after the echo area momentarily displays the message
‘Beginning of buffer’.
If this variable is non-nil, it tells scroll-other-window
which buffer to scroll.
This option specifies the size of the scroll margin—a minimum number of lines between point and the top or bottom of a window. Whenever point gets within this many lines of the top or bottom of the window, redisplay scrolls the text automatically (if possible) to move point out of the margin, closer to the center of the window.
This variable controls how scrolling is done automatically when point moves
off the screen (or into the scroll margin). If the value is a positive
integer n, then redisplay scrolls the text up to n lines in
either direction, if that will bring point back into proper view. This
action is called conservative scrolling. Otherwise, scrolling happens
in the usual way, under the control of other variables such as
scroll-up-aggressively and scroll-down-aggressively.
The default value is zero, which means that conservative scrolling never happens.
The value of this variable should be either nil or a fraction f
between 0 and 1. If it is a fraction, that specifies where on the screen to
put point when scrolling down. More precisely, when a window scrolls down
because point is above the window start, the new start position is chosen to
put point f part of the window height from the top. The larger
f, the more aggressive the scrolling.
A value of nil is equivalent to .5, since its effect is to center
point. This variable automatically becomes buffer-local when set in any
fashion.
Likewise, for scrolling up. The value, f, specifies how far point
should be placed from the bottom of the window; thus, as with
scroll-up-aggressively, a larger value scrolls more aggressively.
This variable is an older variant of scroll-conservatively. The
difference is that it if its value is n, that permits scrolling only
by precisely n lines, not a smaller number. This feature does not
work with scroll-margin. The default value is zero.
If this option is t, scrolling which would move the current point
position out of the window chooses the new position of point so that the
vertical position of the cursor is unchanged, if possible.
If it is non-nil and not t, then the scrolling functions
always preserve the vertical position of point, if possible.
The value of this variable is the number of lines of continuity to retain
when scrolling by full screens. For example, scroll-up with an
argument of nil scrolls so that this many lines at the bottom of the
window appear instead at the top. The default value is 2.
This function scrolls the text in the selected window so that point is displayed at a specified vertical position within the window. It does not “move point” with respect to the text.
If count is a nonnegative number, that puts the line containing point
count lines down from the top of the window. If count is a
negative number, then it counts upward from the bottom of the window, so
that -1 stands for the last usable line in the window. If
count is a non-nil list, then it stands for the line in the
middle of the window.
If count is nil, recenter puts the line containing point
in the middle of the window, then clears and redisplays the entire selected
frame.
When recenter is called interactively, count is the raw prefix
argument. Thus, typing C-u as the prefix sets the count to a
non-nil list, while typing C-u 4 sets count to 4, which
positions the current line four lines from the top.
With an argument of zero, recenter positions the current line at the
top of the window. This action is so handy that some people make a separate
key binding to do this. For example,
(defun line-to-top-of-window () "Scroll current line to top of window. Replaces three keystroke sequence C-u 0 C-l." (interactive) (recenter 0)) (global-set-key [kp-multiply] 'line-to-top-of-window) |
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Ce document a été généré par Eric Reinbold le 13 Octobre 2007 en utilisant texi2html 1.78.