Implement :max-width/:max-height for (ImageMagic) images

* doc/lispref/display.texi (ImageMagick Images): Mention :max-width and
:max-height.

* lisp/net/shr.el (shr-rescale-image): Use the new
:max-width/:max-height functionality.

* src/image.c (compute_image_size): New function to implement
:max-width and :max-height.
(imagemagick_load_image): Use it.

1 files changed, 12 insertions, 28 deletions

diff --git a/lisp/net/shr.el b/lisp/net/shr.el
index 868956d3e21..979743f9588 100644
--- a/lisp/net/shr.el
+++ b/lisp/net/shr.el
@@ -741,34 +741,18 @@ size, and full-buffer size."
 (defun shr-rescale-image (data &optional force)
   "Rescale DATA, if too big, to fit the current buffer.
 If FORCE, rescale the image anyway."
-  (let ((image (create-image data nil t :ascent 100)))
-    (if (or (not (fboundp 'imagemagick-types))
-            (not (get-buffer-window (current-buffer))))
-        image
-      (let* ((size (image-size image t))
-             (width (car size))
-             (height (cdr size))
-             (edges (window-inside-pixel-edges
-                     (get-buffer-window (current-buffer))))
-             (window-width (truncate (* shr-max-image-proportion
-                                        (- (nth 2 edges) (nth 0 edges)))))
-             (window-height (truncate (* shr-max-image-proportion
-                                         (- (nth 3 edges) (nth 1 edges)))))
-             scaled-image)
-        (when (or force
-                  (> height window-height))
-          (setq image (or (create-image data 'imagemagick t
-                                        :height window-height
-                                        :ascent 100)
-                          image))
-          (setq size (image-size image t)))
-        (when (> (car size) window-width)
-          (setq image (or
-                       (create-image data 'imagemagick t
-                                     :width window-width
-                                     :ascent 100)
-                       image)))
-        image))))
+  (if (or (not (fboundp 'imagemagick-types))
+          (not (get-buffer-window (current-buffer))))
+      (create-image data nil t :ascent 100)
+    (let ((edges (window-inside-pixel-edges
+                  (get-buffer-window (current-buffer)))))
+      (create-image
+       data 'imagemagick t
+       :ascent 100
+       :max-width (truncate (* shr-max-image-proportion
+                               (- (nth 2 edges) (nth 0 edges))))
+       :max-height (truncate (* shr-max-image-proportion
+                                (- (nth 3 edges) (nth 1 edges))))))))
 
 ;; url-cache-extract autoloads url-cache.
 (declare-function url-cache-create-filename "url-cache" (url))