Change roles of modes and functions in image-mode.el (Bug#5062).

* image-mode.el: Replace `image-mode-maybe' with `image-mode'
in `auto-mode-alist'.
(image-mode-previous-major-mode): New variable.
(image-minor-mode-map): Rename from `image-mode-text-map'.
(image-mode): Move graceful error-handling code from
`image-minor-mode' to here.  On errors call `image-mode-as-text'.
(image-minor-mode): Remove all image-handling code.
Replace `image-mode-text-map' with `image-minor-mode-map'.
Check for `image-type' in mode-line format string.
(image-mode-maybe): Make obsolete with an alias to `image-mode'.
(image-mode-as-text): New function with most code from
`image-mode-maybe'.
(image-toggle-display-text): Move code that removes image
properties from `image-toggle-display' to here.
(image-toggle-display-image): New function with code that adds
image properties copied from `image-toggle-display'.
(image-toggle-display): Remove most code with leaving only code
that toggles between `image-mode-as-text' and `image-mode'.

3 files changed, 195 insertions, 144 deletions

diff --git a/etc/NEWS b/etc/NEWS
index 6e46678c22b..d398640aa4e 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -351,6 +351,17 @@ be in use:
 ** Support for generating Emacs 18 compatible bytecode (by setting
 the variable `byte-compile-compatibility') has been removed.
 
+** In image-mode.el `image-mode-maybe' is obsolete.  Instead, you can
+either use `image-mode' that displays an image file as the actual image
+inititally, or `image-mode-as-text' when you want to display an image file
+as text inititally.  `image-mode-as-text' is a combination of a non-image
+mode from `auto-mode-alist' (or Fundamental mode) and `image-minor-mode'.
+`image-minor-mode' provides `C-c C-c' key binding to toggle image display.
+`image-toggle-display-text' removes image properties.
+`image-toggle-display-image' adds image properties.
+`image-toggle-display' toggles between `image-mode-as-text' and
+`image-mode'.
+
 
 * Lisp changes in Emacs 23.2
 
diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index cfcb63c4116..732c204f82b 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,26 @@
+2009-12-04  Juri Linkov  <juri@jurta.org>
+
+        Change roles of modes and functions in image-mode.el (Bug#5062).
+
+        * image-mode.el: Replace `image-mode-maybe' with `image-mode'
+        in `auto-mode-alist'.
+        (image-mode-previous-major-mode): New variable.
+        (image-minor-mode-map): Rename from `image-mode-text-map'.
+        (image-mode): Move graceful error-handling code from
+        `image-minor-mode' to here.  On errors call `image-mode-as-text'.
+        (image-minor-mode): Remove all image-handling code.
+        Replace `image-mode-text-map' with `image-minor-mode-map'.
+        Check for `image-type' in mode-line format string.
+        (image-mode-maybe): Make obsolete with an alias to `image-mode'.
+        (image-mode-as-text): New function with most code from
+        `image-mode-maybe'.
+        (image-toggle-display-text): Move code that removes image
+        properties from `image-toggle-display' to here.
+        (image-toggle-display-image): New function with code that adds
+        image properties copied from `image-toggle-display'.
+        (image-toggle-display): Remove most code with leaving only code
+        that toggles between `image-mode-as-text' and `image-mode'.
+
 2009-12-04  Ulf Jasper  <ulf.jasper@web.de>
 
         * net/newst-treeview.el
diff --git a/lisp/image-mode.el b/lisp/image-mode.el
index 2351edc934c..9ca16273a74 100644
--- a/lisp/image-mode.el
+++ b/lisp/image-mode.el
@@ -42,10 +42,10 @@
 ;;;###autoload (push (cons (purecopy "\\.p[bpgn]m\\'") 'image-mode) auto-mode-alist)
 
 ;;;###autoload (push (cons (purecopy "\\.x[bp]m\\'")   'c-mode)     auto-mode-alist)
-;;;###autoload (push (cons (purecopy "\\.x[bp]m\\'")   'image-mode-maybe) auto-mode-alist)
+;;;###autoload (push (cons (purecopy "\\.x[bp]m\\'")   'image-mode) auto-mode-alist)
 
 ;;;###autoload (push (cons (purecopy "\\.svgz?\\'")    'xml-mode)   auto-mode-alist)
-;;;###autoload (push (cons (purecopy "\\.svgz?\\'")    'image-mode-maybe) auto-mode-alist)
+;;;###autoload (push (cons (purecopy "\\.svgz?\\'")    'image-mode) auto-mode-alist)
 
 ;;; Image mode window-info management.
 
@@ -286,6 +286,9 @@ This function assumes the current frame has only one window."
 This variable is used to display the current image type in the mode line.")
 (make-variable-buffer-local 'image-type)
 
+(defvar image-mode-previous-major-mode nil
+  "Internal variable to keep the previous non-image major mode.")
+
 (defvar image-mode-map
   (let ((map (make-sparse-keymap)))
     (suppress-keymap map)
@@ -306,11 +309,11 @@ This variable is used to display the current image type in the mode line.")
     map)
   "Major mode keymap for viewing images in Image mode.")
 
-(defvar image-mode-text-map
+(defvar image-minor-mode-map
   (let ((map (make-sparse-keymap)))
     (define-key map "\C-c\C-c" 'image-toggle-display)
     map)
-  "Major mode keymap for viewing images as text in Image mode.")
+  "Minor mode keymap for viewing images as text in Image mode.")
 
 (defvar bookmark-make-record-function)
 
@@ -320,168 +323,182 @@ This variable is used to display the current image type in the mode line.")
 You can use \\<image-mode-map>\\[image-toggle-display]
 to toggle between display as an image and display as text."
   (interactive)
-  (kill-all-local-variables)
-  (setq major-mode 'image-mode)
-  ;; Use our own bookmarking function for images.
-  (set (make-local-variable 'bookmark-make-record-function)
-       'image-bookmark-make-record)
-
-  ;; Keep track of [vh]scroll when switching buffers
-  (image-mode-setup-winprops)
-
-  (add-hook 'change-major-mode-hook 'image-toggle-display-text nil t)
-  (if (display-images-p)
-      (if (not (image-get-display-property))
-          (image-toggle-display)
-        ;; Set next vars when image is already displayed but local
-        ;; variables were cleared by kill-all-local-variables
+  (condition-case err
+      (progn
+        (unless (display-images-p)
+          (error "Display does not support images"))
+
+        (kill-all-local-variables)
+        (setq major-mode 'image-mode)
+
+        (if (not (image-get-display-property))
+            (progn
+              (image-toggle-display-image)
+              ;; If attempt to display the image fails.
+              (if (not (image-get-display-property))
+                  (error "Invalid image")))
+          ;; Set next vars when image is already displayed but local
+          ;; variables were cleared by kill-all-local-variables
+          (setq cursor-type nil truncate-lines t
+                image-type (plist-get (cdr (image-get-display-property)) :type)))
+
+        (setq mode-name (if image-type (format "Image[%s]" image-type) "Image"))
         (use-local-map image-mode-map)
-        (setq cursor-type nil truncate-lines t
-              image-type (plist-get (cdr (image-get-display-property)) :type)))
-    (setq image-type "text")
-    (use-local-map image-mode-text-map))
-  (setq mode-name (format "Image[%s]" image-type))
-  (run-mode-hooks 'image-mode-hook)
-  (if (display-images-p)
-      (message "%s" (concat
-                     (substitute-command-keys
-                      "Type \\[image-toggle-display] to view as ")
-                     (if (image-get-display-property)
-                         "text" "an image") "."))))
+
+        ;; Use our own bookmarking function for images.
+        (set (make-local-variable 'bookmark-make-record-function)
+             'image-bookmark-make-record)
+
+        ;; Keep track of [vh]scroll when switching buffers
+        (image-mode-setup-winprops)
+
+        (add-hook 'change-major-mode-hook 'image-toggle-display-text nil t)
+        (run-mode-hooks 'image-mode-hook)
+        (message "%s" (concat
+                       (substitute-command-keys
+                        "Type \\[image-toggle-display] to view the image as ")
+                       (if (image-get-display-property)
+                           "text" "an image") ".")))
+    (error
+     (image-mode-as-text)
+     (funcall
+      (if (called-interactively-p 'any) 'error 'message)
+      "Cannot display image: %s" (cdr err)))))
 
 ;;;###autoload
 (define-minor-mode image-minor-mode
   "Toggle Image minor mode.
 With arg, turn Image minor mode on if arg is positive, off otherwise.
-See the command `image-mode' for more information on this mode."
-  nil (:eval (format " Image[%s]" image-type)) image-mode-text-map
+It provides the key \\<image-mode-map>\\[image-toggle-display] \
+to switch back to `image-mode'
+to display an image file as the actual image."
+  nil (:eval (if image-type (format " Image[%s]" image-type) " Image"))
+  image-minor-mode-map
   :group 'image
   :version "22.1"
-  (if (not image-minor-mode)
-      (image-toggle-display-text)
-    (image-mode-setup-winprops)
-    (add-hook 'change-major-mode-hook (lambda () (image-minor-mode -1)) nil t)
-    (if (display-images-p)
-        (condition-case err
-            (progn
-              (if (not (image-get-display-property))
-                  (image-toggle-display)
-                (setq cursor-type nil truncate-lines t
-                      image-type (plist-get (cdr (image-get-display-property))
-                                            :type)))
-              (message "%s"
-                       (concat
-                        (substitute-command-keys
-                         "Type \\[image-toggle-display] to view the image as ")
-                        (if (image-get-display-property)
-                            "text" "an image") ".")))
-          (error
-           (image-toggle-display-text)
-           (funcall
-            (if (called-interactively-p 'any) 'error 'message)
-            "Cannot display image: %s" (cdr err))))
-      (setq image-type "text")
-      (use-local-map image-mode-text-map))))
+  (if image-minor-mode
+      (add-hook 'change-major-mode-hook (lambda () (image-minor-mode -1)) nil t)))
 
 ;;;###autoload
-(defun image-mode-maybe ()
-  "Set major or minor mode for image files.
-Set Image major mode only when there are no other major modes
-associated with a filename in `auto-mode-alist'.  When an image
-filename matches another major mode in `auto-mode-alist' then
-set that major mode and Image minor mode.
-
-See commands `image-mode' and `image-minor-mode' for more
-information on these modes."
+(defun image-mode-as-text ()
+  "Set a non-image mode as major mode in combination with image minor mode.
+A non-image major mode found from `auto-mode-alist' or Fundamental mode
+displays an image file as text.  `image-minor-mode' provides the key
+\\<image-mode-map>\\[image-toggle-display] to switch back to `image-mode'
+to display an image file as the actual image.
+
+You can use `image-mode-as-text' in `auto-mode-alist' when you want
+to display an image file as text inititally.
+
+See commands `image-mode' and `image-minor-mode' for more information
+on these modes."
   (interactive)
-  (let* ((mode-alist
-          (delq nil (mapcar
-                     (lambda (elt)
-                       (unless (memq (or (car-safe (cdr elt)) (cdr elt))
-                                     '(image-mode image-mode-maybe))
-                         elt))
-                     auto-mode-alist))))
-    (if (assoc-default buffer-file-name mode-alist 'string-match)
-        (let ((auto-mode-alist mode-alist)
-              (magic-mode-alist nil))
-          (set-auto-mode)
-          (image-minor-mode t))
-      (image-mode))))
+  ;; image-mode-as-text = normal-mode + image-minor-mode
+  (let ((previous-image-type image-type)) ; preserve `image-type'
+    (if image-mode-previous-major-mode
+        ;; Restore previous major mode that was already found by this
+        ;; function and cached in `image-mode-previous-major-mode'
+        (funcall image-mode-previous-major-mode)
+      (let ((auto-mode-alist
+             (delq nil (mapcar
+                        (lambda (elt)
+                          (unless (memq (or (car-safe (cdr elt)) (cdr elt))
+                                        '(image-mode image-mode-maybe image-mode-as-text))
+                            elt))
+                        auto-mode-alist)))
+            (magic-fallback-mode-alist
+             (delq nil (mapcar
+                        (lambda (elt)
+                          (unless (memq (or (car-safe (cdr elt)) (cdr elt))
+                                        '(image-mode image-mode-maybe image-mode-as-text))
+                            elt))
+                        magic-fallback-mode-alist))))
+        (normal-mode)
+        (set (make-local-variable 'image-mode-previous-major-mode) major-mode)))
+    ;; Restore `image-type' after `kill-all-local-variables' in `normal-mode'.
+    (setq image-type previous-image-type)
+    ;; Enable image minor mode with `C-c C-c'.
+    (image-minor-mode 1)
+    ;; Show the image file as text.
+    (image-toggle-display-text)
+    (message "%s" (concat
+                   (substitute-command-keys
+                    "Type \\[image-toggle-display] to view the image as ")
+                   (if (image-get-display-property)
+                       "text" "an image") "."))))
+
+(define-obsolete-function-alias 'image-mode-maybe 'image-mode "23.2")
 
 (defun image-toggle-display-text ()
-  "Showing the text of the image file."
-  (if (image-get-display-property)
-      (image-toggle-display)))
+  "Show the image file as text.
+Remove text properties that display the image."
+  (let ((inhibit-read-only t)
+        (buffer-undo-list t)
+        (modified (buffer-modified-p)))
+    (remove-list-of-text-properties (point-min) (point-max)
+                                    '(display intangible read-nonsticky
+                                              read-only front-sticky))
+    (set-buffer-modified-p modified)
+    (if (called-interactively-p 'any)
+        (message "Repeat this command to go back to displaying the image"))))
 
 (defvar archive-superior-buffer)
 (defvar tar-superior-buffer)
 (declare-function image-refresh "image.c" (spec &optional frame))
 
+(defun image-toggle-display-image ()
+  "Show the image of the image file.
+Turn the image data into a real image, but only if the whole file
+was inserted."
+  (let* ((filename (buffer-file-name))
+         (data-p (not (and filename
+                           (file-readable-p filename)
+                           (not (file-remote-p filename))
+                           (not (buffer-modified-p))
+                           (not (and (boundp 'archive-superior-buffer)
+                                     archive-superior-buffer))
+                           (not (and (boundp 'tar-superior-buffer)
+                                     tar-superior-buffer)))))
+         (file-or-data (if data-p
+                           (string-make-unibyte
+                            (buffer-substring-no-properties (point-min) (point-max)))
+                         filename))
+         (type (image-type file-or-data nil data-p))
+         (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)))
+         (inhibit-read-only t)
+         (buffer-undo-list t)
+         (modified (buffer-modified-p)))
+    (image-refresh image)
+    (let ((buffer-file-truename nil)) ; avoid changing dir mtime by lock_file
+      (add-text-properties (point-min) (point-max) props)
+      (restore-buffer-modified-p modified))
+    ;; Inhibit the cursor when the buffer contains only an image,
+    ;; because cursors look very strange on top of images.
+    (setq cursor-type nil)
+    ;; This just makes the arrow displayed in the right fringe
+    ;; area look correct when the image is wider than the window.
+    (setq truncate-lines t)
+    ;; Allow navigation of large images
+    (set (make-local-variable 'auto-hscroll-mode) nil)
+    (setq image-type type)
+    (if (eq major-mode 'image-mode)
+        (setq mode-name (format "Image[%s]" type)))
+    (if (called-interactively-p 'any)
+        (message "Repeat this command to go back to displaying the file as text"))))
+
 (defun image-toggle-display ()
   "Start or stop displaying an image file as the actual image.
-This command toggles between showing the text of the image file
-and showing the image as an image."
+This command toggles between `image-mode-as-text' showing the text of
+the image file and `image-mode' showing the image as an image."
   (interactive)
   (if (image-get-display-property)
-      (let ((inhibit-read-only t)
-            (buffer-undo-list t)
-            (modified (buffer-modified-p)))
-        (remove-list-of-text-properties (point-min) (point-max)
-                                        '(display intangible read-nonsticky
-                                                  read-only front-sticky))
-        (set-buffer-modified-p modified)
-        (kill-local-variable 'cursor-type)
-        (kill-local-variable 'truncate-lines)
-        (kill-local-variable 'auto-hscroll-mode)
-        (use-local-map image-mode-text-map)
-        (setq image-type "text")
-        (if (eq major-mode 'image-mode)
-            (setq mode-name "Image[text]"))
-        (if (called-interactively-p 'any)
-            (message "Repeat this command to go back to displaying the image")))
-    ;; Turn the image data into a real image, but only if the whole file
-    ;; was inserted
-    (let* ((filename (buffer-file-name))
-           (data-p (not (and filename
-                             (file-readable-p filename)
-                             (not (file-remote-p filename))
-                             (not (buffer-modified-p))
-                             (not (and (boundp 'archive-superior-buffer)
-                                       archive-superior-buffer))
-                             (not (and (boundp 'tar-superior-buffer)
-                                       tar-superior-buffer)))))
-           (file-or-data (if data-p
-                             (string-make-unibyte
-                              (buffer-substring-no-properties (point-min) (point-max)))
-                           filename))
-           (type (image-type file-or-data nil data-p))
-           (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)))
-           (inhibit-read-only t)
-           (buffer-undo-list t)
-           (modified (buffer-modified-p)))
-      (image-refresh image)
-      (let ((buffer-file-truename nil)) ; avoid changing dir mtime by lock_file
-        (add-text-properties (point-min) (point-max) props)
-        (restore-buffer-modified-p modified))
-      ;; Inhibit the cursor when the buffer contains only an image,
-      ;; because cursors look very strange on top of images.
-      (setq cursor-type nil)
-      ;; This just makes the arrow displayed in the right fringe
-      ;; area look correct when the image is wider than the window.
-      (setq truncate-lines t)
-      ;; Allow navigation of large images
-      (set (make-local-variable 'auto-hscroll-mode) nil)
-      (use-local-map image-mode-map)
-      (setq image-type type)
-      (if (eq major-mode 'image-mode)
-          (setq mode-name (format "Image[%s]" type)))
-      (if (called-interactively-p 'any)
-          (message "Repeat this command to go back to displaying the file as text")))))
+      (image-mode-as-text)
+    (image-mode)))
 
 ;;; Support for bookmark.el
 (declare-function bookmark-make-record-default "bookmark"