* doc-view.el (doc-view-insert-image): Don't modify overlay

associated with pseudo winprops entry, and implement horizontal
centering of image in case it's smaller than the window
(bug#13887).

2 files changed, 61 insertions, 38 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 30f4739a8a9..a5dbac3a5a0 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,10 @@
+2013-03-14  Tassilo Horn  <tsdh@gnu.org>
+
+        * doc-view.el (doc-view-insert-image): Don't modify overlay
+        associated with pseudo winprops entry, and implement horizontal
+        centering of image in case it's smaller than the window
+        (bug#13887).
+
 2013-03-13  Karl Fogel  <kfogel@red-bean.com>
 
         * saveplace.el (save-place-alist-to-file): Don't sort
diff --git a/lisp/doc-view.el b/lisp/doc-view.el
index 0cfdc9a22d1..7290040d168 100644
--- a/lisp/doc-view.el
+++ b/lisp/doc-view.el
@@ -1250,44 +1250,60 @@ ARGS is a list of image descriptors."
   (when doc-view-pending-cache-flush
     (clear-image-cache)
     (setq doc-view-pending-cache-flush nil))
-  (let ((ol (doc-view-current-overlay))
-        (image (if (and file (file-readable-p file))
-                   (if (not (and doc-view-scale-internally
-                                 (fboundp 'imagemagick-types)))
-                       (apply 'create-image file doc-view--image-type nil args)
-                     (unless (member :width args)
-                       (setq args `(,@args :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))
-    (overlay-put ol 'display
-                 (cond
-                  (image
-                   (if slice
-                       (list (cons 'slice slice) image)
-                     image))
-                  ;; We're trying to display a page that doesn't exist.
-                  (doc-view-current-converter-processes
-                   ;; Maybe the page doesn't exist *yet*.
-                   "Cannot display this page (yet)!")
-                  (t
-                   ;; Typically happens if the conversion process somehow
-                   ;; failed.  Better not signal an error here because it
-                   ;; could prevent a subsequent reconversion from fixing
-                   ;; the problem.
-                   (concat "Cannot display this page!\n"
-                           "Maybe because of a conversion failure!"))))
-    (let ((win (overlay-get ol 'window)))
-      (if (stringp (overlay-get ol 'display))
-          (progn            ;Make sure the text is not scrolled out of view.
-            (set-window-hscroll win 0)
-            (set-window-vscroll win 0))
-        (let ((hscroll (image-mode-window-get 'hscroll win))
-              (vscroll (image-mode-window-get 'vscroll win)))
-          ;; Reset scroll settings, in case they were changed.
-          (if hscroll (set-window-hscroll win hscroll))
-          (if vscroll (set-window-vscroll win vscroll)))))))
+  (let ((ol (doc-view-current-overlay)))
+    ;; ol might be deleted (see `doc-view-new-window-function'), in
+    ;; which case we don't want to modify it.
+    (when (overlay-buffer ol)
+      (let* ((image (if (and file (file-readable-p file))
+                        (if (not (and doc-view-scale-internally
+                                      (fboundp 'imagemagick-types)))
+                            (apply 'create-image file doc-view--image-type nil args)
+                          (unless (member :width args)
+                            (setq args `(,@args :width ,doc-view-image-width)))
+                          (apply 'create-image file 'imagemagick nil args))))
+             (slice (doc-view-current-slice))
+             (img-width (and image (car (image-size image))))
+             (displayed-img-width (if (and image slice)
+                                      (* (/ (float (nth 2 slice))
+                                            (car (image-size image 'pixels)))
+                                         img-width)
+                                    img-width))
+             (window-width (window-width (selected-window))))
+        (setf (doc-view-current-image) image)
+        (move-overlay ol (point-min) (point-max))
+        ;; In case the window is wider than the image, center the image
+        ;; horizontally.
+        (overlay-put ol 'before-string
+                     (when (and image (> window-width displayed-img-width))
+                       (propertize " " 'display
+                                   `(space :align-to (+ center (-0.5 . ,displayed-img-width))))))
+        (overlay-put ol 'display
+                     (cond
+                      (image
+                       (if slice
+                           (list (cons 'slice slice) image)
+                         image))
+                      ;; We're trying to display a page that doesn't exist.
+                      (doc-view-current-converter-processes
+                       ;; Maybe the page doesn't exist *yet*.
+                       "Cannot display this page (yet)!")
+                      (t
+                       ;; Typically happens if the conversion process somehow
+                       ;; failed.  Better not signal an error here because it
+                       ;; could prevent a subsequent reconversion from fixing
+                       ;; the problem.
+                       (concat "Cannot display this page!\n"
+                               "Maybe because of a conversion failure!"))))
+        (let ((win (overlay-get ol 'window)))
+          (if (stringp (overlay-get ol 'display))
+              (progn            ;Make sure the text is not scrolled out of view.
+                (set-window-hscroll win 0)
+                (set-window-vscroll win 0))
+            (let ((hscroll (image-mode-window-get 'hscroll win))
+                  (vscroll (image-mode-window-get 'vscroll win)))
+              ;; Reset scroll settings, in case they were changed.
+              (if hscroll (set-window-hscroll win hscroll))
+              (if vscroll (set-window-vscroll win vscroll)))))))))
 
 (defun doc-view-sort (a b)
   "Return non-nil if A should be sorted before B.