(xemacs.info)Scrolling


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11.1 Scrolling
==============

If a buffer contains text that is too large to fit entirely within the
window that is displaying the buffer, XEmacs shows a contiguous section
of the text.  The section shown always contains point.

   "Scrolling" means moving text up or down in the window so that
different parts of the text are visible.  Scrolling forward means that
text moves up, and new text appears at the bottom.  Scrolling backward
moves text down and new text appears at the top.

   Scrolling happens automatically if you move point past the bottom or
top of the window.  You can also explicitly request scrolling with the
commands in this section.

`C-l'
     Clear frame and redisplay, scrolling the selected window to center
     point vertically within it (`recenter').

`C-v'
`pgdn'
`next'
     Scroll forward (a windowful or a specified number of lines)
     (`scroll-up').

`M-v'
`pgup'
`prior'
     Scroll backward (`scroll-down').

`ARG C-l'
     Scroll so point is on line ARG (`recenter').

   The most basic scrolling command is `C-l' (`recenter') with no
argument.  It clears the entire frame and redisplays all windows.  In
addition, it scrolls the selected window so that point is halfway down
from the top of the window.

   The scrolling commands `C-v' and `M-v' let you move all the text in
the window up or down a few lines.  `C-v' (`scroll-up') with an
argument shows you that many more lines at the bottom of the window,
moving the text and point up together as `C-l' might.  `C-v' with a
negative argument shows you more lines at the top of the window.
`Meta-v' (`scroll-down') is like `C-v', but moves in the opposite
direction.

   To read the buffer a windowful at a time, use `C-v' with no
argument.  `C-v' takes the last two lines at the bottom of the window
and puts them at the top, followed by nearly a whole windowful of lines
not previously visible.  Point moves to the new top of the window if it
was in the text scrolled off the top.  `M-v' with no argument moves
backward with similar overlap.  The number of lines of overlap across a
`C-v' or `M-v' is controlled by the variable
`next-screen-context-lines'; by default, it is two.

   Another way to scroll is using `C-l' with a numeric argument.  `C-l'
does not clear the frame when given an argument; it only scrolls the
selected window.  With a positive argument N, `C-l' repositions text to
put point N lines down from the top.  An argument of zero puts point on
the very top line.  Point does not move with respect to the text;
rather, the text and point move rigidly on the frame.  `C-l' with a
negative argument puts point that many lines from the bottom of the
window.  For example, `C-u - 1 C-l' puts point on the bottom line, and
`C-u - 5 C-l' puts it five lines from the bottom.  Just `C-u' as
argument, as in `C-u C-l', scrolls point to the center of the frame.

   Scrolling happens automatically if point has moved out of the visible
portion of the text when it is time to display.  Usually scrolling is
done  to put point vertically centered within the window.  However, if
the variable `scroll-step' has a non-zero value, an attempt is made to
scroll the buffer by that many lines; if that is enough to bring point
back into visibility, that is what happens.

   Scrolling happens automatically if point has moved out of the visible
portion of the text when it is time to display.  Usually scrolling is
done  to put point vertically centered within the window.  However, if
the variable `scroll-step' has a non-zero value, an attempt is made to
scroll the buffer by that many lines; if that is enough to bring point
back into visibility, that is what happens.

   If you set `scroll-step' to a small value because you want to use
arrow keys to scroll the screen without recentering, the redisplay
preemption will likely make XEmacs keep recentering the screen when
scrolling fast, regardless of `scroll-step'.  To prevent this, set
`scroll-conservatively' to a small value, which will have the result of
overriding the redisplay preemption.


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