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If a window is too small to display all the text in its buffer, it displays only a portion of it. Scrolling commands change which portion of the buffer is displayed.
Scrolling forward or up advances the portion of the buffer displayed in the window; equivalently, it moves the buffer text upwards relative to the window. Scrolling backward or down displays an earlier portion of the buffer, and moves the text downwards relative to the window.
In Emacs, scrolling up or down refers to the direction that the text moves in the window, not the direction that the window moves relative to the text. This terminology was adopted by Emacs before the modern meaning of “scrolling up” and “scrolling down” became widespread. Hence, the strange result that <PageDown> scrolls up in the Emacs sense.
The portion of a buffer displayed in a window always contains point. If you move point past the bottom or top of the window, scrolling occurs automatically to bring it back onscreen (see Auto Scrolling). You can also scroll explicitly with these commands:
scroll-up-command) scrolls forward by nearly the
whole window height. The effect is to take the two lines at the
bottom of the window and put them at the top, followed by lines that
were not previously visible. If point was in the text that scrolled
off the top, it ends up on the window's new topmost line. The
<PageDown> (or <next>) key is equivalent to C-v.
scroll-down-command) scrolls backward in a similar
way. The <PageUp> (or <prior>) key is equivalent to
The number of lines of overlap left by these scroll commands is
controlled by the variable
default value is 2. You can supply the commands with a numeric prefix
argument, n, to scroll by n lines; Emacs attempts to leave
point unchanged, so that the text and point move up or down together.
C-v with a negative argument is like M-v and vice versa.
By default, these commands signal an error (by beeping or flashing
the screen) if no more scrolling is possible, because the window has
reached the beginning or end of the buffer. If you change the
t, these commands
move point to the farthest possible position. If point is already
there, the commands signal an error.
Some users like scroll commands to keep point at the same screen
position, so that scrolling back to the same screen conveniently
returns point to its original position. You can enable this behavior
via the variable
scroll-preserve-screen-position. If the value
t, Emacs adjusts point to keep the cursor at the same screen
position whenever a scroll command moves it off-window, rather than
moving it to the topmost or bottommost line. With any other
nil value, Emacs adjusts point this way even if the scroll
command leaves point in the window. This variable affects all the
scroll commands documented in this section, as well as scrolling with
the mouse wheel (see Mouse Commands); in general, it affects any
command that has a non-
See Property Lists.
Sometimes, particularly when you hold down keys such as C-v
and M-v, activating keyboard auto-repeat, Emacs fails to keep up
with the rapid rate of scrolling requested; the display doesn't update
and Emacs can become unresponsive to input for quite a long time. You
can counter this sluggishness by setting the variable
fast-but-imprecise-scrolling to a non-
nil value. This
instructs the scrolling commands not to fontify (see Font Lock)
any unfontified text they scroll over, instead to assume it has the
default face. This can cause Emacs to scroll to somewhat wrong buffer
positions when the faces in use are not all the same size, even with
single (i.e., without auto-repeat) scrolling operations.
The commands M-x scroll-up and M-x scroll-down behave
except they do not obey
scroll-error-top-bottom. Prior to
Emacs 24, these were the default commands for scrolling up and down.
The commands M-x scroll-up-line and M-x scroll-down-line
scroll the current window by one line at a time. If you intend to use
any of these commands, you might want to give them key bindings
(see Init Rebinding).