[PATCH] mouse-1 click follows link

[Kim F. Storm]

Here is the full patch (without doc updates) for the proposed
mouse-1-click-follows-link functionality, including rewriting of
tooltips and making C-h k aware of the remapping.

Index: mouse.el
===================================================================
RCS file: /cvsroot/emacs/emacs/lisp/mouse.el,v
retrieving revision 1.253
diff -c -r1.253 mouse.el
*** mouse.el    28 Oct 2004 23:33:23 -0000      1.253
--- mouse.el    29 Oct 2004 12:57:49 -0000
***************
*** 48,53 ****
--- 48,77 ----
    :type 'boolean
    :group 'mouse)
  
+ (defcustom mouse-1-click-follows-link 350
+   "Non-nil means that clicking mouse-1 on a link follows the link.
+ This is only done for links which have the mouse-face property.
+ 
+ If value is the symbol double, a double click follows the link.
+ 
+ If value is an integer, the time elapsed between pressing and
+ releasing the mouse button determines whether to follow the link
+ or perform the normal mouse-1 action (typically set point).
+ The absolute numeric value specifices the maximum duration of a
+ \"short click\" in milli-seconds.  A positive value means that a
+ short click follows the link, and a longer click performs the
+ normal action.  A negative value gives the opposite behaviour.
+ 
+ Otherwise, a single mouse-1 click unconditionally follows the link.
+ 
+ Note that dragging the mouse never follows the link."
+   :version "21.4"
+   :type '(choice (const :tag "Disabled" nil)
+                (const :tag "Double click" double)
+                  (number :tag "Single click time limit" :value 350)
+                  (other :tag "Single click" t))
+   :group 'mouse)
+ 
  
  ;; Provide a mode-specific menu on a mouse button.
  
***************
*** 731,736 ****
--- 755,764 ----
        (run-hooks 'mouse-leave-buffer-hook)
        (mouse-drag-region-1 start-event))))
  
+ (defun mouse-on-link-p (pos)
+   (and (get-char-property pos 'mouse-face)
+        (not (get-char-property pos 'dont-follow-link))))
+ 
  (defun mouse-drag-region-1 (start-event)
    (mouse-minibuffer-check start-event)
    (let* ((echo-keystrokes 0)
***************
*** 746,751 ****
--- 774,780 ----
                     (nth 3 bounds)
                   ;; Don't count the mode line.
                   (1- (nth 3 bounds))))
+        on-link remap-double-click
         (click-count (1- (event-click-count start-event))))
      (setq mouse-selection-click-count click-count)
      (setq mouse-selection-click-count-buffer (current-buffer))
***************
*** 755,760 ****
--- 784,796 ----
      (if (< (point) start-point)
        (goto-char start-point))
      (setq start-point (point))
+     (setq on-link (and mouse-1-click-follows-link
+                      (mouse-on-link-p start-point)))
+     (setq remap-double-click (and on-link
+                                 (eq mouse-1-click-follows-link 'double)
+                                 (= click-count 1)))
+     (if remap-double-click  ;; Don't expand mouse overlay in links
+       (setq click-count 0))
      (let ((range (mouse-start-end start-point start-point click-count)))
        (move-overlay mouse-drag-overlay (car range) (nth 1 range)
                    (window-buffer start-window))
***************
*** 877,882 ****
--- 913,938 ----
                         (or end-point
                             (= (window-start start-window)
                                start-window-start)))
+               (if (and on-link
+                        (not end-point)
+                        (consp event)
+                        (or remap-double-click
+                            (and
+                             (not (eq mouse-1-click-follows-link 'double))
+                             (= click-count 0)
+                             (= (event-click-count event) 1)
+                             (not (input-pending-p))
+                             (or (not (integerp mouse-1-click-follows-link))
+                                 (let ((t0 (posn-timestamp (event-start 
start-event)))
+                                       (t1 (posn-timestamp (event-end event))))
+                                   (and (integerp t0) (integerp t1)
+                                        (if (> mouse-1-click-follows-link 0)
+                                            (<= (- t1 t0) 
mouse-1-click-follows-link)
+                                          (< (- t0 t1) 
mouse-1-click-follows-link)))))
+                             (or (not double-click-time)
+                                 (sit-for 0 (if (integerp double-click-time)
+                                                double-click-time 500) t)))))
+                   (setcar event 'mouse-2))
                (setq unread-command-events
                      (cons event unread-command-events)))))
        (delete-overlay mouse-drag-overlay)))))

*** help.el     25 Oct 2004 14:43:57 +0200      1.270
--- help.el     29 Oct 2004 12:35:18 +0200      
***************
*** 609,625 ****
            (princ "\n   which is ")
            (describe-function-1 defn)
            (when up-event
!             (let ((defn (or (string-key-binding up-event) (key-binding 
up-event))))
                (unless (or (null defn) (integerp defn) (equal defn 'undefined))
!                 (princ "\n\n-------------- up event ---------------\n\n")
!                 (princ (key-description up-event))
                  (if (windowp window)
                      (princ " at that spot"))
                  (princ " runs the command ")
                  (prin1 defn)
                  (princ "\n   which is ")
!                 (describe-function-1 defn))))
!           (print-help-return-message)))))))
  
  
  (defun describe-mode (&optional buffer)
--- 609,666 ----
            (princ "\n   which is ")
            (describe-function-1 defn)
            (when up-event
!             (let ((ev (aref up-event 0))
!                   (descr (key-description up-event))
!                   (hdr "\n\n-------------- up event ---------------\n\n")
!                   defn
!                   mouse-1-tricky mouse-1-remapped)
!               (when (and (consp ev)
!                          (eq (car ev) 'mouse-1)
!                          (windowp window)
!                          mouse-1-click-follows-link
!                          (not (eq mouse-1-click-follows-link 'double))
!                          (with-current-buffer (window-buffer window)
!                            (mouse-on-link-p (posn-point (event-start ev)))))
!                 (setq mouse-1-tricky (integerp mouse-1-click-follows-link)
!                       mouse-1-remapped (or (not mouse-1-tricky)
!                                            (> mouse-1-click-follows-link 0)))
!                 (if mouse-1-remapped
!                     (setcar ev 'mouse-2)))
!               (setq defn (or (string-key-binding up-event) (key-binding 
up-event)))
                (unless (or (null defn) (integerp defn) (equal defn 'undefined))
!                 (princ (if mouse-1-tricky
!                            "\n\n----------------- up-event (short click) 
----------------\n\n"
!                          hdr))
!                 (setq hdr nil)
!                 (princ descr)
                  (if (windowp window)
                      (princ " at that spot"))
+                 (if mouse-1-remapped
+                     (princ " is remapped to <mouse-2>\n  which" ))
                  (princ " runs the command ")
                  (prin1 defn)
                  (princ "\n   which is ")
!                 (describe-function-1 defn))
!               (when mouse-1-tricky
!                 (setcar ev
!                         (if (> mouse-1-click-follows-link 0) 'mouse-1 
'mouse-2))
!                 (setq defn (or (string-key-binding up-event) (key-binding 
up-event)))
!                 (unless (or (null defn) (integerp defn) (equal defn 
'undefined))
!                   (princ (or hdr
!                              "\n\n----------------- up-event (long click) 
----------------\n\n"))
!                   (princ "Pressing ")
!                   (princ descr)
!                   (if (windowp window)
!                       (princ " at that spot"))
!                   (princ (format " for longer than %d milli-seconds\n"
!                                  (abs mouse-1-click-follows-link)))
!                   (if (not mouse-1-remapped)
!                       (princ " remaps it to <mouse-2> which" ))
!                   (princ " runs the command ")
!                   (prin1 defn)
!                   (princ "\n   which is ")
!                   (describe-function-1 defn))))
!           (print-help-return-message))))))))
  
  
  (defun describe-mode (&optional buffer)

*** tooltip.el  01 Sep 2003 17:45:17 +0200      1.34
--- tooltip.el  29 Oct 2004 12:36:23 +0200      
***************
*** 480,486 ****
  (defun tooltip-show-help-function (msg)
    "Function installed as `show-help-function'.
  MSG is either a help string to display, or nil to cancel the display."
!   (let ((previous-help tooltip-help-message))
      (setq tooltip-help-message msg)
      (cond ((null msg)
           ;; Cancel display.  This also cancels a delayed tip, if
--- 481,505 ----
  (defun tooltip-show-help-function (msg)
    "Function installed as `show-help-function'.
  MSG is either a help string to display, or nil to cancel the display."
!   (let ((previous-help tooltip-help-message)
!       mp pos)
!     (if (and mouse-1-click-follows-link
!            (stringp msg)
!            (save-match-data
!              (string-match "^mouse-2" msg))
!            (setq mp (mouse-pixel-position))
!            (consp (setq pos (cdr mp)))
!            (setq pos (posn-at-x-y (car pos) (cdr pos) (car mp)))
!            (windowp (posn-window pos)))
!       (with-current-buffer (window-buffer (posn-window pos))
!         (if (mouse-on-link-p (posn-point pos))
!             (setq msg (concat
!                   (cond
!                    ((eq mouse-1-click-follows-link 'double) "double-")
!                    ((and (integerp mouse-1-click-follows-link)
!                          (< mouse-1-click-follows-link 0)) "Long ")
!                    (t ""))
!                   "mouse-1" (substring msg 7))))))
      (setq tooltip-help-message msg)
      (cond ((null msg)
           ;; Cancel display.  This also cancels a delayed tip, if

-- 
Kim F. Storm <address@hidden> http://www.cua.dk