* lisp/image.el: Support image scaling with mouse in other buffer.

* lisp/image.el (image-increase-size, image-decrease-size):
Add optional arg position.
(image-mouse-increase-size, image-mouse-decrease-size):
Use '(point-marker)' for arg position.
(image--get-image): Use get-char-property from position if non-nil,
and its buffer.
(image--get-imagemagick-and-warn, image--change-size):
Add optional arg position.

1 files changed, 16 insertions, 12 deletions

diff --git a/lisp/image.el b/lisp/image.el
index f4ed4e79fc0..254e7e58b67 100644
--- a/lisp/image.el
+++ b/lisp/image.el
@@ -1012,7 +1012,7 @@ has no effect."
 
 (imagemagick-register-types)
 
-(defun image-increase-size (&optional n)
+(defun image-increase-size (&optional n position)
   "Increase the image size by a factor of N.
 If N is 3, then the image size will be increased by 30%.  The
 default is 20%."
@@ -1027,9 +1027,10 @@ default is 20%."
                        #'image--change-size
                        (if n
                            (1+ (/ (prefix-numeric-value n) 10.0))
-                         1.2)))
+                         1.2)
+                       position))
 
-(defun image-decrease-size (&optional n)
+(defun image-decrease-size (&optional n position)
   "Decrease the image size by a factor of N.
 If N is 3, then the image size will be decreased by 30%.  The
 default is 20%."
@@ -1044,7 +1045,8 @@ default is 20%."
                        #'image--change-size
                        (if n
                            (- 1 (/ (prefix-numeric-value n) 10.0))
-                         0.8)))
+                         0.8)
+                       position))
 
 (defun image-mouse-increase-size (&optional event)
   "Increase the image size using the mouse."
@@ -1052,7 +1054,7 @@ default is 20%."
   (when (listp event)
     (save-window-excursion
       (posn-set-point (event-start event))
-      (image-increase-size))))
+      (image-increase-size nil (point-marker)))))
 
 (defun image-mouse-decrease-size (&optional event)
   "Decrease the image size using the mouse."
@@ -1060,27 +1062,29 @@ default is 20%."
   (when (listp event)
     (save-window-excursion
       (posn-set-point (event-start event))
-      (image-decrease-size))))
+      (image-decrease-size nil (point-marker)))))
 
-(defun image--get-image ()
+(defun image--get-image (&optional position)
   "Return the image at point."
-  (let ((image (get-char-property (point) 'display)))
+  (let ((image (get-char-property (or position (point)) 'display
+                                  (when (markerp position)
+                                    (marker-buffer position)))))
     (unless (eq (car-safe image) 'image)
       (error "No image under point"))
     image))
 
-(defun image--get-imagemagick-and-warn ()
+(defun image--get-imagemagick-and-warn (&optional position)
   (unless (or (fboundp 'imagemagick-types) (image-transforms-p))
     (error "Cannot rescale images on this terminal"))
-  (let ((image (image--get-image)))
+  (let ((image (image--get-image position)))
     (image-flush image)
     (when (and (fboundp 'imagemagick-types)
                (not (image-transforms-p)))
       (plist-put (cdr image) :type 'imagemagick))
     image))
 
-(defun image--change-size (factor)
-  (let* ((image (image--get-imagemagick-and-warn))
+(defun image--change-size (factor &optional position)
+  (let* ((image (image--get-imagemagick-and-warn position))
          (new-image (image--image-without-parameters image))
          (scale (image--current-scaling image new-image)))
     (setcdr image (cdr new-image))