Subject: bug#50269: 27.2; Request: use GTK continuous scroll events for smooth touchpad scrolling

From: Kévin Le Gouguec <[email-masked]>
Date: Tue, 31 Aug 2021 18:33:13 +0200

Eli Zaretskii <[email-masked]> writes:

>> From: Alexander Huntley <[email-masked]>
>> Cc: [email-masked]
>> Date: Mon, 30 Aug 2021 22:26:45 +0100
>> 
>> pixel-scroll-mode may shift the display one pixel at a time, but it
>> also "snaps" the display to certain larger intervals, (integer numbers
>> of lines).
>
> I don't think I follow: what is this "snapping" you are alluding to
> here?  Can you tell me how to reproduce this snapping, so I could
> understand better the problem you have in mind?

With pixel-scroll-mode on, when pixel-resolution-fine-flag is nil (the
default), I cannot get Emacs to scroll up by "just a few pixels",
however small my movement on the touchpad.  Emacs always waits for
"enough movement" to scroll up a complete line, although the *animation*
is indeed done pixel-by-pixel (as opposed to line-by-line when
pixel-scroll-mode is off).

On e.g. Mousepad (XFCE's text editor), if I move "just a bit" on the
touchpad, the display moves by "just a few pixels", i.e. less than a
full line.  FWIW setting pixel-resolution-fine-flag to 1 seems to allow
Emacs to do the same.

(I hope I understood Alexander's problem correctly; apologies for the
noise if not)