Animated image API.

http://lists.gnu.org/archive/html/emacs-devel/2010-03/msg00211.html

* image.el (image-animate-max-time): New defcustom.
(image-animated-types): New defconst.
(create-animated-image, image-animate-timer)
(image-animate-start, image-animate-stop, image-animate-timeout)
(image-animated-p): New functions.

* image-mode.el (image-toggle-display-image):
Replace `create-image' with `create-animated-image'.

3 files changed, 119 insertions, 1 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 8ac8d5ed450..cf3be1586e5 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,17 @@
+2010-03-07  Kim F. Storm  <storm@cua.dk>
+
+        Animated image API.
+        http://lists.gnu.org/archive/html/emacs-devel/2010-03/msg00211.html
+
+        * image.el (image-animate-max-time): New defcustom.
+        (image-animated-types): New defconst.
+        (create-animated-image, image-animate-timer)
+        (image-animate-start, image-animate-stop, image-animate-timeout)
+        (image-animated-p): New functions.
+
+        * image-mode.el (image-toggle-display-image):
+        Replace `create-image' with `create-animated-image'.
+
 2010-01-27  Stephen Berman  <stephen.berman@gmx.net>
 
         * calendar/diary-lib.el (diary-unhide-everything): Handle narrowed
diff --git a/lisp/image-mode.el b/lisp/image-mode.el
index f3cdc05da16..1d999b50007 100644
--- a/lisp/image-mode.el
+++ b/lisp/image-mode.el
@@ -464,7 +464,7 @@ was inserted."
                             (buffer-substring-no-properties (point-min) (point-max)))
                          filename))
          (type (image-type file-or-data nil data-p))
-         (image (create-image file-or-data type data-p))
+         (image (create-animated-image file-or-data type data-p))
          (props
           `(display ,image
                     intangible ,image
diff --git a/lisp/image.el b/lisp/image.el
index 944c6135e23..e5dfe1a3996 100644
--- a/lisp/image.el
+++ b/lisp/image.el
@@ -584,7 +584,111 @@ Example:
   (declare (doc-string 3))
   `(defvar ,symbol (find-image ',specs) ,doc))
 
+
+;;; Animated image API
 
+(defcustom image-animate-max-time 30
+  "Time in seconds to animate images."
+  :type 'integer
+  :version "22.1"
+  :group 'image)
+
+(defconst image-animated-types '(gif)
+  "List of supported animated image types.")
+
+;;;###autoload
+(defun create-animated-image (file-or-data &optional type data-p &rest props)
+  "Create an animated image.
+FILE-OR-DATA is an image file name or image data.
+Optional TYPE is a symbol describing the image type.  If TYPE is omitted
+or nil, try to determine the image type from its first few bytes
+of image data.  If that doesn't work, and FILE-OR-DATA is a file name,
+use its file extension as image type.
+Optional DATA-P non-nil means FILE-OR-DATA is a string containing image data.
+Optional PROPS are additional image attributes to assign to the image,
+like, e.g. `:mask MASK'.
+Value is the image created, or nil if images of type TYPE are not supported.
+
+Images should not be larger than specified by `max-image-size'."
+  (setq type (image-type file-or-data type data-p))
+  (when (image-type-available-p type)
+    (let* ((animate (memq type image-animated-types))
+           (image
+            (append (list 'image :type type (if data-p :data :file) file-or-data)
+                    (if animate '(:index 0 :mask heuristic))
+                    props)))
+      (if animate
+          (image-animate-start image))
+      image)))
+
+(defun image-animate-timer (image)
+  "Return the animation timer for image IMAGE."
+  ;; See cancel-function-timers
+  (let ((tail timer-list) timer)
+    (while tail
+      (setq timer (car tail)
+            tail (cdr tail))
+      (if (and (eq (aref timer 5) #'image-animate-timeout)
+               (consp (aref timer 6))
+               (eq (car (aref timer 6)) image))
+          (setq tail nil)
+        (setq timer nil)))
+    timer))
+
+(defun image-animate-start (image &optional max-time)
+  "Start animation of image IMAGE.
+Optional second arg MAX-TIME is number of seconds to animate image,
+or t to animate infinitely."
+  (let ((anim (image-animated-p image))
+        timer tmo)
+    (when anim
+      (if (setq timer (image-animate-timer image))
+          (setcar (nthcdr 3 (aref timer 6)) max-time)
+        (setq tmo (* (cdr anim) 0.01))
+        (setq max-time (or max-time image-animate-max-time))
+        (run-with-timer tmo nil #'image-animate-timeout
+                        image 1 (car anim)
+                        (if (numberp max-time)
+                            (- max-time tmo)
+                          max-time))))))
+
+(defun image-animate-stop (image)
+  "Stop animation of image."
+  (let ((timer (image-animate-timer image)))
+    (when timer
+      (cancel-timer timer))))
+
+(defun image-animate-timeout (image ino count time-left)
+  (if (>= ino count)
+      (setq ino 0))
+  (plist-put (cdr image) :index ino)
+  (force-window-update)
+  (let ((anim (image-animated-p image)) tmo)
+    (when anim
+      (setq tmo (* (cdr anim) 0.01))
+      (unless (and (= ino 0) (numberp time-left) (< time-left tmo))
+        (run-with-timer tmo nil #'image-animate-timeout
+                        image (1+ ino) count
+                        (if (numberp time-left)
+                            (- time-left tmo)
+                          time-left))))))
+
+(defun image-animated-p (image)
+  "Return non-nil if image is animated.
+Actually, return value is a cons (IMAGES . DELAY) where IMAGES
+is the number of sub-images in the animated image, and DELAY
+is the delay in 100ths of a second until the next sub-image
+shall be displayed."
+  (cond
+   ((eq (plist-get (cdr image) :type) 'gif)
+    (let* ((extdata (image-extension-data image))
+           (images (plist-get extdata 'count))
+           (anim (plist-get extdata #xF9)))
+      (and (integerp images) (> images 1)
+           (stringp anim) (>= (length anim) 4)
+           (cons images (+ (aref anim 1) (* (aref anim 2) 256))))))))
+
+
 (provide 'image)
 
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