2008-01-29 Tassilo Horn <tassilo@member.fsf.org>

	* image-mode.el (image-mode-current-vscroll)
	(image-mode-current-hscroll): New variables.
	(image-set-window-hscroll, image-set-window-vscroll): New
	functions.
	(image-forward-hscroll, image-next-line, image-bol, image-eol)
	(image-bob, image-eob): Use them.
	(image-reset-current-vhscroll): New function.
	(image-mode): Make new variables buffer-local and reset [vh]scroll
	on window configuration changes.

diff --git a/lisp/image-mode.el b/lisp/image-mode.el
index 6b02db50134ad3edb5971eef5ca14192c8e8f5a9..7af8d0f82daee2d10b9de720ee7d11bcf250e613 100644 (file)
--- a/lisp/image-mode.el
+++ b/lisp/image-mode.el
@@ -50,22 +50,37 @@
 
 ;;; Image scrolling functions
 
+(defvar image-mode-current-vscroll nil)
+(defvar image-mode-current-hscroll nil)
+
+(defun image-set-window-vscroll (window vscroll &optional pixels-p)
+  (setq image-mode-current-vscroll vscroll)
+  (set-window-vscroll window vscroll pixels-p))
+
+(defun image-set-window-hscroll (window ncol)
+  (setq image-mode-current-hscroll ncol)
+  (set-window-hscroll window ncol))
+
+(defun image-reset-current-vhscroll ()
+  (set-window-hscroll (selected-window) image-mode-current-hscroll)
+  (set-window-vscroll (selected-window) image-mode-current-vscroll))
+
 (defun image-forward-hscroll (&optional n)
   "Scroll image in current window to the left by N character widths.
 Stop if the right edge of the image is reached."
   (interactive "p")
   (cond ((= n 0) nil)
        ((< n 0)
-        (set-window-hscroll (selected-window)
-                            (max 0 (+ (window-hscroll) n))))
+        (image-set-window-hscroll (selected-window)
+                                  (max 0 (+ (window-hscroll) n))))
        (t
         (let* ((image (get-char-property (point-min) 'display))
                (edges (window-inside-edges))
                (win-width (- (nth 2 edges) (nth 0 edges)))
                (img-width (ceiling (car (image-size image)))))
-          (set-window-hscroll (selected-window)
-                              (min (max 0 (- img-width win-width))
-                                   (+ n (window-hscroll))))))))
+          (image-set-window-hscroll (selected-window)
+                                    (min (max 0 (- img-width win-width))
+                                         (+ n (window-hscroll))))))))
 
 (defun image-backward-hscroll (&optional n)
   "Scroll image in current window to the right by N character widths.
@@ -79,16 +94,16 @@ Stop if the bottom edge of the image is reached."
   (interactive "p")
   (cond ((= n 0) nil)
        ((< n 0)
-        (set-window-vscroll (selected-window)
-                            (max 0 (+ (window-vscroll) n))))
+        (image-set-window-vscroll (selected-window)
+                                  (max 0 (+ (window-vscroll) n))))
        (t
         (let* ((image (get-char-property (point-min) 'display))
                (edges (window-inside-edges))
                (win-height (- (nth 3 edges) (nth 1 edges)))
                (img-height (ceiling (cdr (image-size image)))))
-          (set-window-vscroll (selected-window)
-                              (min (max 0 (- img-height win-height))
-                                   (+ n (window-vscroll))))))))
+          (image-set-window-vscroll (selected-window)
+                                    (min (max 0 (- img-height win-height))
+                                         (+ n (window-vscroll))))))))
 
 (defun image-previous-line (&optional n)
   "Scroll image in current window downward by N lines.
@@ -146,7 +161,7 @@ stopping if the top or bottom edge of the image is reached."
   (and arg
        (/= (setq arg (prefix-numeric-value arg)) 1)
        (image-next-line (- arg 1)))
-  (set-window-hscroll (selected-window) 0))
+  (image-set-window-hscroll (selected-window) 0))
 
 (defun image-eol (arg)
   "Scroll horizontally to the right edge of the image in the current window.
@@ -160,14 +175,14 @@ stopping if the top or bottom edge of the image is reached."
         (edges (window-inside-edges))
         (win-width (- (nth 2 edges) (nth 0 edges)))
         (img-width (ceiling (car (image-size image)))))
-    (set-window-hscroll (selected-window)
-                       (max 0 (- img-width win-width)))))
+    (image-set-window-hscroll (selected-window)
+                             (max 0 (- img-width win-width)))))
 
 (defun image-bob ()
   "Scroll to the top-left corner of the image in the current window."
   (interactive)
-  (set-window-hscroll (selected-window) 0)
-  (set-window-vscroll (selected-window) 0))
+  (image-set-window-hscroll (selected-window) 0)
+  (image-set-window-vscroll (selected-window) 0))
 
 (defun image-eob ()
   "Scroll to the bottom-right corner of the image in the current window."
@@ -178,8 +193,8 @@ stopping if the top or bottom edge of the image is reached."
         (img-width (ceiling (car (image-size image))))
         (win-height (- (nth 3 edges) (nth 1 edges)))
         (img-height (ceiling (cdr (image-size image)))))
-    (set-window-hscroll (selected-window) (max 0 (- img-width win-width)))
-    (set-window-vscroll (selected-window) (max 0 (- img-height win-height)))))
+    (image-set-window-hscroll (selected-window) (max 0 (- img-width win-width)))
+    (image-set-window-vscroll (selected-window) (max 0 (- img-height win-height)))))
 
 ;;; Image Mode setup
 
@@ -224,6 +239,15 @@ to toggle between display as an image and display as text."
   ;; Use our own bookmarking function for images.
   (set (make-local-variable 'bookmark-make-cell-function)
        'image-bookmark-make-cell)
+
+  ;; Keep track of [vh]scroll when switching buffers
+  (set (make-local-variable 'image-mode-current-hscroll)
+       (window-hscroll (selected-window)))
+  (set (make-local-variable 'image-mode-current-vscroll)
+       (window-vscroll (selected-window)))
+  (add-hook 'window-configuration-change-hook
+           'image-reset-current-vhscroll nil t)
+
   (add-hook 'change-major-mode-hook 'image-toggle-display-text nil t)
   (if (and (display-images-p)
           (not (get-char-property (point-min) 'display)))
@@ -255,9 +279,9 @@ See the command `image-mode' for more information on this mode."
       (setq image-type "text"))
     (add-hook 'change-major-mode-hook (lambda () (image-minor-mode -1)) nil t)
     (message "%s" (concat (substitute-command-keys
-                     "Type \\[image-toggle-display] to view the image as ")
-                    (if (get-char-property (point-min) 'display)
-                        "text" "an image") "."))))
+                          "Type \\[image-toggle-display] to view the image as ")
+                         (if (get-char-property (point-min) 'display)
+                             "text" "an image") "."))))
 
 ;;;###autoload
 (defun image-mode-maybe ()
@@ -333,9 +357,9 @@ and showing the image as an image."
           (image (create-image file-or-data type data-p))
           (props
            `(display ,image
-             intangible ,image
-             rear-nonsticky (display intangible)
-             read-only t front-sticky (read-only)))
+                     intangible ,image
+                     rear-nonsticky (display intangible)
+                     read-only t front-sticky (read-only)))
           (inhibit-read-only t)
           (buffer-undo-list t)
           (modified (buffer-modified-p)))