bug#62250: 29.0.60; Allow context menu from text properties to not override everything

[Juri Linkov <juri@linkov.net>]

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>> Just for the record, this would be useful to create a
>> context menu for images.
>
> The patch below will allow using the text property like
>
>   'context-menu-functions '(image-context-menu)

Here is a complete patch that uses the new text property
for create a context menu for images:


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diff --git a/lisp/iimage.el b/lisp/iimage.el
index b4c175a7b63..8235c4a6fdb 100644
--- a/lisp/iimage.el
+++ b/lisp/iimage.el
@@ -134,6 +134,7 @@ iimage-mode-buffer
                                     :max-width (- (nth 2 edges) (nth 0 edges))
 				    :max-height (- (nth 3 edges) (nth 1 edges)))
                      keymap ,image-map
+                     context-menu-functions (image-context-menu)
                      modification-hooks
                      (iimage-modification-hook)))
                 (remove-list-of-text-properties
diff --git a/lisp/image.el b/lisp/image.el
index 2372fd1ce09..11bf46c80cc 100644
--- a/lisp/image.el
+++ b/lisp/image.el
@@ -188,6 +188,29 @@ image-map
   "C-<wheel-up>"   #'image-mouse-increase-size
   "C-<mouse-4>"    #'image-mouse-increase-size)
 
+(defun image-context-menu (menu click)
+  "Populate MENU with image-related commands at CLICK."
+  (when (mouse-posn-property (event-start click) 'display)
+    (define-key menu [image-separator] menu-bar-separator)
+    (let ((easy-menu (make-sparse-keymap "Image")))
+      (easy-menu-define nil easy-menu nil
+        '("Image"
+          ["Zoom In" image-increase-size
+           :help "Enlarge the image"]
+          ["Zoom Out" image-decrease-size
+           :help "Shrink the image"]
+          ["Rotate Clockwise" image-rotate
+           :help "Rotate the image"]
+          ["Flip horizontally" image-flip-horizontally
+           :help "Flip horizontally"]
+          ["Flip vertically" image-flip-vertically
+           :help "Flip vertically"]))
+      (dolist (item (reverse (lookup-key easy-menu [menu-bar image])))
+        (when (consp item)
+          (define-key menu (vector (car item)) (cdr item))))))
+
+  menu)
+
 (defun image-load-path-for-library (library image &optional path no-error)
   "Return a suitable search path for images used by LIBRARY.
 
@@ -615,6 +638,7 @@ put-image
       (overlay-put overlay 'put-image t)
       (overlay-put overlay 'before-string string)
       (overlay-put overlay 'keymap image-map)
+      (overlay-put overlay 'context-menu-functions '(image-context-menu))
       overlay)))
 
 
@@ -665,7 +689,9 @@ insert-image
 				      image)
                                    rear-nonsticky t
 				   inhibit-isearch ,inhibit-isearch
-                                   keymap ,image-map))))
+                                   keymap ,image-map
+                                   context-menu-functions
+                                   (image-context-menu)))))
 
 
 ;;;###autoload
@@ -702,7 +728,9 @@ insert-sliced-image
 	  (add-text-properties start (point)
 			       `(display ,(list (list 'slice x y dx dy) image)
 					 rear-nonsticky (display)
-                                         keymap ,image-map))
+                                         keymap ,image-map
+                                         context-menu-functions
+                                         (image-context-menu)))
 	  (setq x (+ x dx))))
       (setq x 0.0
 	    y (+ y dy))
diff --git a/lisp/mouse.el b/lisp/mouse.el
index 6b9accd6758..2cd2840bad9 100644
--- a/lisp/mouse.el
+++ b/lisp/mouse.el
@@ -368,9 +368,10 @@ context-menu-map
 the function `context-menu-filter-function'."
   (let* ((menu (make-sparse-keymap (propertize "Context Menu" 'hide t)))
          (click (or click last-input-event))
-         (window (posn-window (event-start click)))
-         (fun (mouse-posn-property (event-start click)
-                                   'context-menu-function)))
+         (start (event-start click))
+         (window (posn-window start))
+         (fun (mouse-posn-property start 'context-menu-function))
+         (funs (mouse-posn-property start 'context-menu-functions)))
 
     (unless (eq (selected-window) window)
       (select-window window))
@@ -380,7 +381,9 @@ context-menu-map
       (run-hook-wrapped 'context-menu-functions
                         (lambda (fun)
                           (setq menu (funcall fun menu click))
-                          nil)))
+                          nil))
+      (dolist (fun funs)
+        (setq menu (funcall fun menu click))))
 
     ;; Remove duplicate separators as well as ones at the beginning or
     ;; end of the menu.