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bug#45628: 28.0.50; Scrolling on echo area with pixel-scroll-mode enable
From: |
Tak Kunihiro |
Subject: |
bug#45628: 28.0.50; Scrolling on echo area with pixel-scroll-mode enabled locks up Emacs |
Date: |
Mon, 4 Jan 2021 17:57:48 +0900 |
>> As the Subject says, scrolling using the mouse wheel on the echo area
>> causes Emacs to freeze/lock up (cursor is changed to spinning circle),
>> when pixel-scroll-mode is enabled.
>
> Tak, can you please look into this? The code infloops inside
> pixel-scroll-down, here:
>
> (while (pixel-point-at-bottom-p amt) ; prevent too late (multi tries)
> (vertical-motion -1)) ; move point upward
>
> because the mini-window is normally just one screen line high, so its
> top and bottom coincide.
>
> Shouldn't we exit the loop when vertical-motion returns zero, which
> means it didn't move?
>
> A similar loop exists in pixel-scroll-up, AFAICS.
Thank you to shoot the problem.
I confirmed the problem and Eli's suggestion solves it.
I think that following patch would work but usage of `while’
does not look cool. If there can is better style, please
suggest me.
diff --git a/lisp/pixel-scroll.el b/lisp/pixel-scroll.el
index cc0e159fae..c266c54a06 100644
--- a/lisp/pixel-scroll.el
+++ b/lisp/pixel-scroll.el
@@ -132,8 +132,8 @@ pixel-scroll-up
(pixel-line-height))))
(if (pixel-eob-at-top-p) ; when end-of-the-buffer is close
(scroll-up 1) ; relay on robust method
- (while (pixel-point-at-top-p amt) ; prevent too late (multi tries)
- (vertical-motion 1)) ; move point downward
+ (while (and (pixel-point-at-top-p amt) ; prevent too late (multi
tries)
+ (equal (vertical-motion 1) 1))) ; move point downward
(pixel-scroll-pixel-up amt)))))) ; move scope downward
(defun pixel-scroll-down (&optional arg)
@@ -149,8 +149,8 @@ pixel-scroll-down
pixel-resolution-fine-flag
(frame-char-height))
(pixel-line-height -1))))
- (while (pixel-point-at-bottom-p amt) ; prevent too late (multi tries)
- (vertical-motion -1)) ; move point upward
+ (while (and (pixel-point-at-bottom-p amt) ; prevent too late (multi
tries)
+ (equal (vertical-motion -1) -1))) ; move point upward
(if (or (pixel-bob-at-top-p amt) ; when beginning-of-the-buffer is seen
(pixel-eob-at-top-p)) ; for file with a long line
(scroll-down 1) ; relay on robust method