Display a mode-line frame counter for animated images

* lisp/image.el (image-current-frame): New variable.
(image-animate-timeout): Set image-current-frame.

* lisp/image-mode.el (image-mode): For animated images,
display a frame counter via mode-line-process.

3 files changed, 18 insertions, 2 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 09645ec4741..b932054261d 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,5 +1,10 @@
 2013-02-16  Glenn Morris  <rgm@gnu.org>
 
+        * image.el (image-current-frame): New variable.
+        (image-animate-timeout): Set image-current-frame.
+        * image-mode.el (image-mode): For animated images,
+        display a frame counter via mode-line-process.
+
         * font-lock.el (lisp-font-lock-keywords-1): Add defvar-local.
 
 2013-02-15  Stefan Monnier  <monnier@iro.umontreal.ca>
diff --git a/lisp/image-mode.el b/lisp/image-mode.el
index 196336717db..fcbea945714 100644
--- a/lisp/image-mode.el
+++ b/lisp/image-mode.el
@@ -409,11 +409,18 @@ to toggle between display as an image and display as text."
         (run-mode-hooks 'image-mode-hook)
         (let ((image (image-get-display-property))
               (msg1 (substitute-command-keys
-                     "Type \\[image-toggle-display] to view the image as ")))
+                     "Type \\[image-toggle-display] to view the image as "))
+              animated)
           (cond
            ((null image)
             (message "%s" (concat msg1 "an image.")))
-           ((image-animated-p image)
+           ((setq animated (image-animated-p image))
+            (setq image-current-frame (or (plist-get (cdr image) :index) 0)
+                  mode-line-process
+                  `(:eval (propertize (format " [%s/%s]"
+                                              (1+ image-current-frame)
+                                              ,(car animated))
+                                      'help-echo "Frame number")))
             (message "%s"
                      (concat msg1 "text, or "
                              (substitute-command-keys
diff --git a/lisp/image.el b/lisp/image.el
index 73b25f6da67..e0521ad065a 100644
--- a/lisp/image.el
+++ b/lisp/image.el
@@ -657,6 +657,9 @@ number, play until that number of seconds has elapsed."
         (setq timer nil)))
     timer))
 
+(defvar-local image-current-frame nil
+  "The frame index of the current animated image.")
+
 ;; FIXME? The delay may not be the same for different sub-images,
 ;; hence we need to call image-animated-p to return it.
 ;; But it also returns count, so why do we bother passing that as an
@@ -672,6 +675,7 @@ LIMIT determines when to stop.  If t, loop forever.  If nil, stop
  after LIMIT seconds have elapsed.
 The minimum delay between successive frames is 0.01s."
   (plist-put (cdr image) :index n)
+  (setq image-current-frame n)
   (force-window-update)
   (setq n (1+ n))
   (let* ((time (float-time))