[PATCH 3/3] emacs: show: add invisibility button action

[Mark Walters <markwalters1009@gmail.com>]

This adds a button action to show hidden parts. In this version "t"
toggles the visibility of a part. In addition "RET" on a non-shown
part shows it.

The button is used to hide parts when appropriate (eg text/html in
multipart/alternative).
---
 emacs/notmuch-show.el |   36 +++++++++++++++++++++++++++++++++++-
 1 files changed, 35 insertions(+), 1 deletions(-)

diff --git a/emacs/notmuch-show.el b/emacs/notmuch-show.el
index 3215ebc..a4daff8 100644
--- a/emacs/notmuch-show.el
+++ b/emacs/notmuch-show.el
@@ -478,6 +478,7 @@ message at DEPTH in the current thread."
     (define-key map "v" 'notmuch-show-part-button-view)
     (define-key map "o" 'notmuch-show-part-button-interactively-view)
     (define-key map "|" 'notmuch-show-part-button-pipe)
+    (define-key map "t" 'notmuch-show-toggle-invisible-part-action)
     map)
   "Submap for button commands")
 (fset 'notmuch-show-part-button-map notmuch-show-part-button-map)
@@ -555,6 +556,31 @@ message at DEPTH in the current thread."
     (let ((handle (mm-make-handle (current-buffer) (list content-type))))
       (mm-pipe-part handle))))
 
+;; This is taken from notmuch-wash: maybe it should be unified?
+(defun notmuch-show-toggle-invisible-part-action (&optional button no-redisplay)
+  (interactive)
+  (let* ((button (or button (button-at (point))))
+	 (overlay (button-get button 'overlay))
+	 (invis-spec (button-get button 'invisibility-spec))
+	 (show (invisible-p invis-spec)))
+    (when overlay
+      (if show
+	  (remove-from-invisibility-spec invis-spec)
+	(add-to-invisibility-spec invis-spec))
+      (let* ((new-start (button-start button))
+	     (button-label (button-get button :base-label))
+	     (old-point (point))
+	     (inhibit-read-only t))
+	(goto-char new-start)
+	(insert "[ " button-label (if show " ]" " (not shown) ]"))
+	(let ((old-end (button-end button)))
+	  (move-overlay button new-start (point))
+	  (delete-region (point) old-end))
+	(goto-char (min old-point (1- (button-end button)))))
+      (unless no-redisplay
+	(force-window-update)
+	(redisplay t)))))
+
 (defun notmuch-show-multipart/*-to-list (part)
   (mapcar (lambda (inner-part) (plist-get inner-part :content-type))
 	  (plist-get part :content)))
@@ -867,6 +893,11 @@ message at DEPTH in the current thread."
 
 	(button-put button 'invisibility-spec invis-spec)
 	(button-put button 'overlay overlay))
+
+      ;; We toggle the button for hidden parts as that gets the
+      ;; button label right.
+      (when not-shown
+	(notmuch-show-toggle-invisible-part-action button t))
       (goto-char (point-max)))))
 
 (defun notmuch-show-insert-bodypart (msg part depth &optional not-shown)
@@ -1996,7 +2027,10 @@ the user (see `notmuch-show-stash-mlarchive-link-alist')."
 
 (defun notmuch-show-part-button-default (&optional button)
   (interactive)
-  (notmuch-show-part-button-internal button notmuch-show-part-button-default-action))
+  (let ((button (or button (button-at (point)))))
+    (if (invisible-p (button-get button 'invisibility-spec))
+	(notmuch-show-toggle-invisible-part-action button)
+      (notmuch-show-part-button-internal button notmuch-show-part-button-default-action))))
 
 (defun notmuch-show-part-button-save (&optional button)
   (interactive)
-- 
1.7.9.1