Make image-mode give better feedback when the buffer is empty

* lisp/image-mode.el (image-mode): Give a less confusing message
if we don't have any image data (bug#16062).  Also leave the
buffer in fundamental mode.

diff --git a/lisp/image-mode.el b/lisp/image-mode.el
index 948e62e10d010ce0e06d2b0f21bc08a1ea4d51b5..4c719f7cda2f8d8d1bcad4b568b5d7a784f2e6c0 100644 (file)
--- a/lisp/image-mode.el
+++ b/lisp/image-mode.el
@@ -612,6 +612,15 @@ Key bindings:
   (setq major-mode 'image-mode)
   (setq image-transform-resize image-auto-resize)
 
+  ;; Bail out early if we have no image data.
+  (if (zerop (buffer-size))
+      (funcall (if (called-interactively-p 'any) 'error 'message)
+               (if (file-exists-p buffer-file-name)
+                   "Empty file"
+                 "(New file)"))
+    (image-mode--display)))
+
+(defun image-mode--display ()
   (if (not (image-get-display-property))
       (progn
         (when (condition-case err