Implement display-time wrap/line-prefix feature

Revision: emacs@sv.gnu.org/emacs--devo--0--patch-1305

3 files changed, 51 insertions, 0 deletions

diff --git a/doc/lispref/ChangeLog b/doc/lispref/ChangeLog
index e4fa5529ac4..17b3b61f73e 100644
--- a/doc/lispref/ChangeLog
+++ b/doc/lispref/ChangeLog
@@ -1,3 +1,8 @@
+2008-07-01  Miles Bader  <miles@gnu.org>
+
+        * text.texi (Special Properties):
+        * display.texi (Truncation): Add wrap-prefix and line-prefix.
+
 2008-06-28  Johan Bockgård  <bojohan@gnu.org>
 
         * display.texi (Other Image Types): Fix copy/paste error; say
diff --git a/doc/lispref/display.texi b/doc/lispref/display.texi
index b09227d3f6c..e7cb51072cc 100644
--- a/doc/lispref/display.texi
+++ b/doc/lispref/display.texi
@@ -191,6 +191,29 @@ If it is non-@code{nil}, these lines are truncated; otherwise,
   When horizontal scrolling (@pxref{Horizontal Scrolling}) is in use in
 a window, that forces truncation.
 
+@defvar wrap-prefix
+If this buffer-local variable is non-@code{nil}, the prefix it defines
+will be added at display-time to the beginning of every continuation
+line due to text wrapping (so if lines are truncated, the wrap-prefix
+is never used).  It may be a string, an image, or a stretch-glyph such
+as used by the `display' text-property.  @xref{Display Property}.
+
+A wrap-prefix may also be specified for regions of text using the
+@code{wrap-prefix} text-property (which takes precedence over the
+value of the @code{wrap-prefix} variable).  @xref{Special Properties}.
+@end defvar
+
+@defvar line-prefix
+If this buffer-local variable is non-@code{nil}, the prefix it defines
+will be added at display-time to the beginning of every
+non-continuation line It may be a string, an image, or a stretch-glyph
+such as used by the `display' text-property.  @xref{Display Property}.
+
+A line-prefix may also be specified for regions of text using the
+@code{line-prefix} text-property (which takes precedence over the
+value of the @code{line-prefix} variable).  @xref{Special Properties}.
+@end defvar
+
   If your buffer contains @emph{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
diff --git a/doc/lispref/text.texi b/doc/lispref/text.texi
index b1a8653def5..ac2fb090722 100644
--- a/doc/lispref/text.texi
+++ b/doc/lispref/text.texi
@@ -3167,6 +3167,29 @@ A newline can have a @code{line-height} text or overlay property that
 controls the total height of the display line ending in that newline.
 @xref{Line Height}.
 
+@item wrap-prefix
+If text has a @code{wrap-prefix} property, the prefix it defines will
+be added at display-time to the beginning of every continuation line
+due to text wrapping (so if lines are truncated, the wrap-prefix is
+never used).  It may be a string, an image, or a stretch-glyph such as
+used by the @code{display} text-property.  @xref{Display Property}.
+
+A wrap-prefix may also be specified for an entire buffer using the
+@code{wrap-prefix} buffer-local variable (however, a
+@code{wrap-prefix} text-property takes precedence over the value of
+the @code{wrap-prefix} variable).  @xref{Truncation}.
+
+@item line-prefix
+If text has a @code{line-prefix} property, the prefix it defines will
+be added at display-time to the beginning of every non-continuation
+line.  It may be a string, an image, or a stretch-glyph such as used
+by the @code{display} text-property.  @xref{Display Property}.
+
+A line-prefix may also be specified for an entire buffer using the
+@code{line-prefix} buffer-local variable (however, a
+@code{line-prefix} text-property takes precedence over the value of
+the @code{line-prefix} variable).  @xref{Truncation}.
+
 @item modification-hooks
 @cindex change hooks for a character
 @cindex hooks for changing a character