2 files changed, 29 insertions, 4 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index b24eae7b4e8..be65508a115 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,10 @@
+2011-01-05  Tassilo Horn  <tassilo@member.fsf.org>
+
+        * doc-view.el (doc-view-image-width): New variable.
+        (doc-view-enlarge, doc-view-insert-image): Prefer imagemagick
+        backend for PNG images, and do dynamic rescaling instead of
+        reconverting the whole doc.
+
 2011-01-05  Glenn Morris  <rgm@gnu.org>
 
         * emacs-lisp/rx.el (rx-repeat): Replace CL function.
diff --git a/lisp/doc-view.el b/lisp/doc-view.el
index 801cddd1620..7ec8b3954e0 100644
--- a/lisp/doc-view.el
+++ b/lisp/doc-view.el
@@ -168,6 +168,12 @@ Higher values result in larger images."
   :type 'number
   :group 'doc-view)
 
+(defcustom doc-view-image-width 850
+  "Default image width.
+Has only an effect if imagemagick support is compiled into emacs."
+  :type 'number
+  :group 'doc-view)
+
 (defcustom doc-view-dvipdfm-program (executable-find "dvipdfm")
   "Program to convert DVI files to PDF.
 
@@ -641,9 +647,17 @@ OpenDocument format)."
 (defun doc-view-enlarge (factor)
   "Enlarge the document."
   (interactive (list doc-view-shrink-factor))
-  (set (make-local-variable 'doc-view-resolution)
-       (* factor doc-view-resolution))
-  (doc-view-reconvert-doc))
+  (if (eq (plist-get (cdr (doc-view-current-image)) :type)
+          'imagemagick)
+      ;; ImageMagick supports on-the-fly-rescaling
+      (progn
+        (set (make-local-variable 'doc-view-image-width)
+             (ceiling (* factor doc-view-image-width)))
+        (doc-view-insert-image (plist-get (cdr (doc-view-current-image)) :file)
+                               :width doc-view-resolution))
+    (set (make-local-variable 'doc-view-resolution)
+         (ceiling (* factor doc-view-resolution)))
+    (doc-view-reconvert-doc)))
 
 (defun doc-view-shrink (factor)
   "Shrink the document."
@@ -949,7 +963,11 @@ ARGS is a list of image descriptors."
     (setq doc-view-pending-cache-flush nil))
   (let ((ol (doc-view-current-overlay))
         (image (if (and file (file-readable-p file))
-                   (apply 'create-image file 'png nil args)))
+                   (if (not (fboundp 'imagemagick-types))
+                       (apply 'create-image file 'png nil args)
+                     (unless (member :width args)
+                       (setq args (append args (list :width doc-view-image-width))))
+                     (apply 'create-image file 'imagemagick nil args))))
         (slice (doc-view-current-slice)))
     (setf (doc-view-current-image) image)
     (move-overlay ol (point-min) (point-max))