From a434024c4e452b4f2495921832b00e801568939e Mon Sep 17 00:00:00 2001
From: Jose A Ortega Ruiz <jao@gnu.org>
Date: Wed, 28 Sep 2022 03:02:57 +0100
Subject: [PATCH] docview: new customization options for imenu

* doc/emacs/misc.texi (DocView Navigation):
* lisp/doc-view.el (doc-view-imenu-title-format, doc-view-imenu-flatten):
(doc-view--imenu-subtree): customizable format for imenu entry titles,
and flag to disable nested submenus.
* lisp/doc-view.el (doc-view--pdf-outline): clean up whitespace
markers '\r' and '\t' in imenu item titles.
---
 doc/emacs/misc.texi |  9 +++++++--
 lisp/doc-view.el    | 29 +++++++++++++++++++++++++----
 2 files changed, 32 insertions(+), 6 deletions(-)

diff --git a/doc/emacs/misc.texi b/doc/emacs/misc.texi
index 04f7f2e921..cef2580f3b 100644
--- a/doc/emacs/misc.texi
+++ b/doc/emacs/misc.texi
@@ -585,11 +585,16 @@ DocView Navigation
 @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.
+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-flatten}.
 
 @node DocView Searching
 @subsection DocView Searching
diff --git a/lisp/doc-view.el b/lisp/doc-view.el
index fa583df12b..9e3bb6e46c 100644
--- a/lisp/doc-view.el
+++ b/lisp/doc-view.el
@@ -219,6 +219,23 @@ doc-view-imenu-enabled
   :type 'boolean
   :version "29.1")
 
+(defcustom doc-view-imenu-title-format "%t (%p)"
+  "Format string for document section titles in imenu.
+
+The special markers '%t' and '%p' are replaced by the section
+title and page number in this format string, which uses
+`format-spec'.
+
+For instance, setting this variable to \"%t\" will produce items
+showing only titles and no page number."
+  :type 'string
+  :version "29.1")
+
+(defcustom doc-view-imenu-flatten nil
+  "Whether to generate a flat list of sections instead of a nested tree."
+  :type 'boolean
+  :version "29.1")
+
 (defcustom doc-view-svg-background "white"
   "Background color for svg images.
 See `doc-view-mupdf-use-svg'."
@@ -1898,7 +1915,8 @@ doc-view--pdf-outline
       (goto-char (point-min))
       (while (re-search-forward doc-view--outline-rx nil t)
         (push `((level . ,(length (match-string 1)))
-                (title . ,(match-string 2))
+                (title . ,(replace-regexp-in-string "\\\\[rt]" " "
+                                                    (match-string 2)))
                 (page . ,(string-to-number (match-string 3))))
               outline)))
     (nreverse outline)))
@@ -1911,11 +1929,14 @@ doc-view--imenu-subtree
 level.  Returns that imenu alist together with any other pending outline
 entries at an upper level."
   (let ((level (alist-get 'level (car outline)))
+        (nested (not doc-view-imenu-flatten))
         (index nil))
-    (while (and (car outline) (<= level (alist-get 'level (car outline))))
+    (while (and (car outline)
+                (or nested (<= level (alist-get 'level (car outline)))))
       (let-alist (car outline)
-        (let ((title (format "%s (%s)" .title .page)))
-          (if (> .level level)
+        (let ((title (format-spec doc-view-imenu-title-format
+                                  `((?t . ,.title) (?p . ,.page)))))
+          (if (and nested (> .level level))
               (let ((sub (doc-view--imenu-subtree outline act))
                     (fst (car index)))
                 (setq index (cdr index))
-- 
2.37.2