Re: visual-line-mode

[Stefan Monnier <monnier@iro.umontreal.ca>]

> I expect emacs primitives will need improvement to work for the
> word-wrapping case (and display-time line-prefixes which I've hacked up
> locally), so perhaps they can be improved to work better in general too.

After looking a bit more at the various visual line movement packages,
and remembering that I've just added a `cols' arg to vertical-motion,
I believe the patch below provides basically the behavior we want.

As it turns out, it doesn't work right with word-wrapping because
posn-at-point returns funny X positions.  Probably the same underlying
bug causes sometimes mouse-clicks to place point elsewhere than under
the mouse.


        Stefan


=== modified file 'lisp/simple.el'
--- lisp/simple.el	2008-06-21 02:48:08 +0000
+++ lisp/simple.el	2008-06-29 13:36:08 +0000
@@ -4030,6 +4030,16 @@
 	 (t
 	  (set-window-vscroll nil (frame-char-height) t)))))))
 
+(defvar line-move-visual t)
+
+(defun line-move-visual (arg)
+  (unless (and (floatp temporary-goal-column)
+               (or (memq last-command '(next-line previous-line))
+                   ;; In case we're called from some other command.
+                   (eq last-command this-command)))
+    (setq temporary-goal-column
+          (/ (car (nth 2 (posn-at-point))) 1.0 (frame-char-width))))
+  (vertical-motion (cons (truncate temporary-goal-column) arg)))
 
 ;; This is like line-move-1 except that it also performs
 ;; vertical scrolling of tall images if appropriate.
@@ -4046,7 +4056,9 @@
 	       (not executing-kbd-macro)
 	       (line-move-partial arg noerror to-end))
     (set-window-vscroll nil 0 t)
-    (line-move-1 arg noerror to-end)))
+    (if line-move-visual
+        (line-move-visual arg)
+      (line-move-1 arg noerror to-end))))
 
 ;; This is the guts of next-line and previous-line.
 ;; Arg says how many lines to move.