Add imenu index function for DjVu files in doc-view

* lisp/doc-view.el (doc-view-pdfdraw-program): Prefer mutool
over other names.
(doc-view-imenu-enabled): Tweak the default value to check for
'djvused', and make it obsolete.
(doc-view--djvu-outline, doc-view--parse-djvu-outline): Add new
functions to return imenu index for a Djvu file.
(doc-view--outline): Add new function to create the imenu index
depending on the file type.
(doc-view--outline): Document new possible variable value.
(doc-view-imenu-index): Use the above function instead.
(doc-view-imenu-setup): Try to create the imenu index
unconditionally.
* doc/emacs/misc.texi (DocView Navigation): Mention index
creation using 'djvused' too.
* etc/NEWS: Announce the change.  (Bug#73530)

1 files changed, 9 insertions, 9 deletions

diff --git a/doc/emacs/misc.texi b/doc/emacs/misc.texi
index b074eb034b2..7b11a829b0b 100644
--- a/doc/emacs/misc.texi
+++ b/doc/emacs/misc.texi
@@ -581,17 +581,17 @@ you instead want the image to be re-rendered at the new size, set
 default size for DocView, customize the variable
 @code{doc-view-resolution}.
 
-@vindex doc-view-imenu-enabled
 @vindex doc-view-imenu-flatten
 @vindex doc-view-imenu-format
-  When the @command{mutool} program is available, DocView will use it
-to generate entries for an outline menu, making it accessible via the
-@code{imenu} facility (@pxref{Imenu}).  To disable this functionality
-even when @command{mutool} can be found on your system, customize the
-variable @code{doc-view-imenu-enabled} to the @code{nil} value.  You
-can further customize how @code{imenu} items are formatted and
-displayed using the variables @code{doc-view-imenu-format} and
-@code{doc-view-imenu-flatten}.
+@vindex doc-view-djvused-program
+  DocView can generate an outline menu for PDF and DjVu documents using
+the @command{mutool} and the @command{djvused} programs respectively
+when they are available.  This is made accessible via the @code{imenu}
+facility (@pxref{Imenu}).  You can customize how @code{imenu} items are
+formatted and displayed using the variables @code{doc-view-imenu-format}
+and @code{doc-view-imenu-flatten}.  The filename of the
+@command{djvused} program can be customized by changing the
+@code{doc-view-djvused-program} user option.
 
 @cindex registers, in DocView mode
 @findex doc-view-page-to-register