GNU Info

(elisp)Truncation

---

Next: The Echo Area Prev: Forcing Redisplay Up: Display

---

Enter node , (file) or (file)node

Truncation
==========

   When a line of text extends beyond the right edge of a window, the
line can either be continued on the next screen line, or truncated to
one screen line.  The additional screen lines used to display a long
text line are called "continuation" lines.  Normally, a `$' in the
rightmost column of the window indicates truncation; a `\' on the
rightmost column indicates a line that "wraps" onto the next line,
which is also called "continuing" the line.  (The display table can
specify alternative indicators; see Note: Display Tables.)

   Note that continuation is different from filling; continuation
happens on the screen only, not in the buffer contents, and it breaks a
line precisely at the right margin, not at a word boundary.  Note:
Filling.

 - User Option: truncate-lines
     This buffer-local variable controls how Emacs displays lines that
     extend beyond the right edge of the window.  The default is `nil',
     which specifies continuation.  If the value is non-`nil', then
     these lines are truncated.

     If the variable `truncate-partial-width-windows' is non-`nil',
     then truncation is always used for side-by-side windows (within one
     frame) regardless of the value of `truncate-lines'.

 - User Option: default-truncate-lines
     This variable is the default value for `truncate-lines', for
     buffers that do not have buffer-local values for it.

 - User Option: truncate-partial-width-windows
     This variable controls display of lines that extend beyond the
     right edge of the window, in side-by-side windows (Note: Splitting
     Windows).  If it is non-`nil', these lines are truncated;
     otherwise, `truncate-lines' says what to do with them.

   When horizontal scrolling (Note: Horizontal Scrolling) is in use in
a window, that forces truncation.

   You can override the glyphs that indicate continuation or truncation
using the display table; see Note: Display Tables.

   If your buffer contains _very_ long lines, and you use continuation
to display them, just thinking about them can make Emacs redisplay
slow.  The column computation and indentation functions also become
slow.  Then you might find it advisable to set `cache-long-line-scans'
to `t'.

 - Variable: cache-long-line-scans
     If this variable is non-`nil', various indentation and motion
     functions, and Emacs redisplay, cache the results of scanning the
     buffer, and consult the cache to avoid rescanning regions of the
     buffer unless they are modified.

     Turning on the cache slows down processing of short lines somewhat.

     This variable is automatically buffer-local in every buffer.