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bug#51590: follow-mode is broken with header-line and tab-line
From: |
Alan Mackenzie |
Subject: |
bug#51590: follow-mode is broken with header-line and tab-line |
Date: |
Sun, 7 Nov 2021 12:48:22 +0000 |
Hello, Juri and Eli.
On Thu, Nov 04, 2021 at 19:29:28 +0200, Juri Linkov wrote:
> retitle 51590 follow-mode is broken with header-line and tab-line
> quit
> >> The most low-level function of follow-mode is follow-calc-win-end.
> >> When global-tab-line-mode is enabled, follow-calc-win-end
> >> returns the same values as when global-tab-line-mode is disabled.
> > Can you step through that function and see which part is misbehaving
> > there?
> >> I don't understand what more low-level function doesn't take
> >> into account the height of the tab-line. Maybe the problem is
> >> in pos-visible-in-window-p? Or maybe different values returned
> >> by window-inside-pixel-edges and window-end?
> > I don't know the answer, but I see that header-line-format is
> > mentioned in one place in follow.el, and that is not a good sign...
> Indeed, I tested with the header-line, and it has the same problem,
> so retitled this bug report.
> After trial and error, I arrived to the following patch that completely
> fixes these problems. However, I can't explain how it works.
I've spent some time on this patch, and I've transformed it into a
similar patch that I can explain, and I believe is nearly correct[*].
Could you possibly try it out in your system. Thanks!
diff --git a/lisp/follow.el b/lisp/follow.el
index b64f4cb734..2ca2c1f17b 100644
--- a/lisp/follow.el
+++ b/lisp/follow.el
@@ -667,7 +667,8 @@ follow-scroll-down
(scroll-down-command arg))
(arg (follow-scroll-down-arg arg))
(t
- (let* ((windows (follow-all-followers))
+ (let* ((orig-point (point))
+ (windows (follow-all-followers))
(win (car (reverse windows)))
(start (window-start (car windows))))
(if (eq start (point-min))
@@ -678,11 +679,14 @@ follow-scroll-down
(select-window win)
(goto-char start)
(vertical-motion (- (- (window-height win)
- (if header-line-format 2 1)
- next-screen-context-lines)))
+ (if header-line-format 2 1) ; always
mode-line
+ (if tab-line-format 1 0)
+ next-screen-context-lines)))
(set-window-start win (point))
- (goto-char start)
- (vertical-motion (- next-screen-context-lines 1))
+ (if (< orig-point (window-end win t))
+ (goto-char orig-point)
+ (goto-char start)
+ (vertical-motion (- next-screen-context-lines 1)))
(setq follow-internal-force-redisplay t))))))
(put 'follow-scroll-down 'scroll-command t)
@@ -947,7 +951,11 @@ follow-calc-win-end
(let* ((win (or win (selected-window)))
(edges (window-inside-pixel-edges win))
(ht (- (nth 3 edges) (nth 1 edges)))
- (last-line-pos (posn-point (posn-at-x-y 0 (1- ht) win))))
+ (last-line-pos (posn-point
+ (posn-at-x-y 0 (+ (window-header-line-height win)
+ (window-tab-line-height win)
+ (1- ht))
+ win))))
(if (pos-visible-in-window-p last-line-pos win)
(let ((end (window-end win t)))
(list end (pos-visible-in-window-p (point-max) win)))
[*] There is a situation which is not new, where if the buffer is too
short to fill all the windows, and it is already scrolled up far,
follow-scroll-down will scroll a correct amount, but leave point in a
random position.
--
Alan Mackenzie (Nuremberg, Germany).
- bug#51590: follow-mode is broken with header-line and tab-line, (continued)
- bug#51590: follow-mode is broken with header-line and tab-line, martin rudalics, 2021/11/06
- bug#51590: follow-mode is broken with header-line and tab-line, Alan Mackenzie, 2021/11/08
- bug#51590: follow-mode is broken with header-line and tab-line, Eli Zaretskii, 2021/11/08
- bug#51590: follow-mode is broken with header-line and tab-line, martin rudalics, 2021/11/09
- bug#51590: follow-mode is broken with header-line and tab-line, martin rudalics, 2021/11/09
- bug#51590: follow-mode is broken with header-line and tab-line, martin rudalics, 2021/11/04
- bug#51590: follow-mode is broken with header-line and tab-line,
Alan Mackenzie <=
- bug#51590: follow-mode is broken with header-line and tab-line, Eli Zaretskii, 2021/11/07
- bug#51590: follow-mode is broken with header-line and tab-line, Alan Mackenzie, 2021/11/07
- bug#51590: follow-mode is broken with header-line and tab-line, Juri Linkov, 2021/11/07
- bug#51590: follow-mode is broken with header-line and tab-line, Alan Mackenzie, 2021/11/07
- bug#51590: follow-mode is broken with header-line and tab-line, Juri Linkov, 2021/11/07
- bug#51590: follow-mode is broken with header-line and tab-line, Alan Mackenzie, 2021/11/08
bug#51590: follow-mode is broken with header-line and tab-line, Stefan Kangas, 2021/11/05