bug#65360: emacs 29.1 with MSYS2: vertical scrolling with touchpad not working

bug#65360: emacs 29.1 with MSYS2: vertical scrolling with touchpad not working

[Vincent Torri]

Hello

I have a DELL XPS 13 with Windows 10, and I installed emacs 29.1 with
msys2. When I try to scroll vertically to the bottom of the file with
touchpad, using 2 fingers,  emacs content is going briefly to bottom
then is going upper

no problem with other applications

Vincent Torri

bug#65360: emacs 29.1 with MSYS2: vertical scrolling with touchpad not working

[Eli Zaretskii]

merge 65360 65070
thanks

> From: Vincent Torri <vincent.torri@gmail.com>
> Date: Fri, 18 Aug 2023 07:15:39 +0200
> 
> I have a DELL XPS 13 with Windows 10, and I installed emacs 29.1 with
> msys2. When I try to scroll vertically to the bottom of the file with
> touchpad, using 2 fingers,  emacs content is going briefly to bottom
> then is going upper

This is a known bug#65070.  Unfortunately, we don't currently have
anyone with access to such a machine who could debug the relevant code
and tell what is wrong with it.  If you can run Emacs under GDB on
that machine and report some findings (I can provide more detailed
instructions), we might be able to fix this.

bug#65360: emacs 29.1 with MSYS2: vertical scrolling with touchpad not working

[Vincent Torri]

On Fri, Aug 18, 2023 at 7:40 AM Eli Zaretskii <eliz@gnu.org> wrote:
>
> merge 65360 65070
> thanks
>
> > From: Vincent Torri <vincent.torri@gmail.com>
> > Date: Fri, 18 Aug 2023 07:15:39 +0200
> >
> > I have a DELL XPS 13 with Windows 10, and I installed emacs 29.1 with
> > msys2. When I try to scroll vertically to the bottom of the file with
> > touchpad, using 2 fingers,  emacs content is going briefly to bottom
> > then is going upper
>
> This is a known bug#65070.

ok

>  Unfortunately, we don't currently have
> anyone with access to such a machine who could debug the relevant code
> and tell what is wrong with it.  If you can run Emacs under GDB on
> that machine and report some findings (I can provide more detailed
> instructions), we might be able to fix this.

I can do that, tell me what to do

Vincent

bug#65360: emacs 29.1 with MSYS2: vertical scrolling with touchpad not working

[Eli Zaretskii]

> From: Vincent Torri <vincent.torri@gmail.com>
> Date: Fri, 18 Aug 2023 07:51:45 +0200
> Cc: 65360@debbugs.gnu.org
> 
> >  Unfortunately, we don't currently have
> > anyone with access to such a machine who could debug the relevant code
> > and tell what is wrong with it.  If you can run Emacs under GDB on
> > that machine and report some findings (I can provide more detailed
> > instructions), we might be able to fix this.
> 
> I can do that, tell me what to do

Thank you.

The relevant code is in w32term.c:w32_construct_mouse_wheel.  For
starters, could you please step through that function and tell what
you see when you scroll with the touchpad?  In particular, does the
value of 'delta' become positive or negative depending on the
direction of the scrolling?  Also, what are the computed values of p.x
and p.y, and what are the values in the structure pointer to by
'result' immediately before the function returns?

Note: to be able to show values of Lisp objects, you need to tell GDB
to read the src/.gdbinit file in the Emacs source tree:

  (gdb) source /path/to/emacs/src/.gdbinit

P.S. It goes without saying that you will need to have the sources of
Emacs 29.1 available, if you don't already.

bug#65360: emacs 29.1 with MSYS2: vertical scrolling with touchpad not working

[Vincent Torri]

On Fri, Aug 18, 2023 at 8:28 AM Eli Zaretskii <eliz@gnu.org> wrote:
>
> > From: Vincent Torri <vincent.torri@gmail.com>
> > Date: Fri, 18 Aug 2023 07:51:45 +0200
> > Cc: 65360@debbugs.gnu.org
> >
> > >  Unfortunately, we don't currently have
> > > anyone with access to such a machine who could debug the relevant code
> > > and tell what is wrong with it.  If you can run Emacs under GDB on
> > > that machine and report some findings (I can provide more detailed
> > > instructions), we might be able to fix this.
> >
> > I can do that, tell me what to do
>
> Thank you.
>
> The relevant code is in w32term.c:w32_construct_mouse_wheel.

ok

>  For
> starters, could you please step through that function and tell what
> you see when you scroll with the touchpad?  In particular, does the
> value of 'delta' become positive or negative depending on the
> direction of the scrolling?  Also, what are the computed values of p.x
> and p.y, and what are the values in the structure pointer to by
> 'result' immediately before the function returns?
>
> Note: to be able to show values of Lisp objects, you need to tell GDB
> to read the src/.gdbinit file in the Emacs source tree:
>
>   (gdb) source /path/to/emacs/src/.gdbinit
>
> P.S. It goes without saying that you will need to have the sources of
> Emacs 29.1 available, if you don't already.

maybe it will be simpler for me to compile emacs and debug it directly
with some printf(). At least i know where to look at now

Vincent

bug#65360: emacs 29.1 with MSYS2: vertical scrolling with touchpad not working

[Eli Zaretskii]

> From: Vincent Torri <vincent.torri@gmail.com>
> Date: Fri, 18 Aug 2023 08:41:05 +0200
> Cc: 65360@debbugs.gnu.org
> 
> maybe it will be simpler for me to compile emacs and debug it directly
> with some printf(). At least i know where to look at now

That can also be done, with the caveats that:

  . to look at some variable, you will have to add code and recompile
    Emacs
  . if the function(s) in question are invoked frequently when you
    scroll, you will have a lot of output, without a good way of
    knowing which output was caused by which UI gesture

But that doesn't make printf-debugging impossible, so if it's easier
for you, let's try that!

Thanks.

bug#65360: emacs 29.1 with MSYS2: vertical scrolling with touchpad not working

[Vincent Torri]

On Fri, Aug 18, 2023 at 8:56 AM Eli Zaretskii <eliz@gnu.org> wrote:
>
> > From: Vincent Torri <vincent.torri@gmail.com>
> > Date: Fri, 18 Aug 2023 08:41:05 +0200
> > Cc: 65360@debbugs.gnu.org
> >
> > maybe it will be simpler for me to compile emacs and debug it directly
> > with some printf(). At least i know where to look at now
>
> That can also be done, with the caveats that:
>
>   . to look at some variable, you will have to add code and recompile
>     Emacs

normally, make will recompile only what is needed, one file

>   . if the function(s) in question are invoked frequently when you
>     scroll, you will have a lot of output, without a good way of
>     knowing which output was caused by which UI gesture

well, there will not a lot of output : just scrolling once to the
bottom is problematic

> But that doesn't make printf-debugging impossible, so if it's easier
> for you, let's try that!

i'll inform you about what I get

Vincent

bug#65360: emacs 29.1 with MSYS2: vertical scrolling with touchpad not working

[Vincent Torri]

On Fri, Aug 18, 2023 at 9:01 AM Vincent Torri <vincent.torri@gmail.com> wrote:
>
> On Fri, Aug 18, 2023 at 8:56 AM Eli Zaretskii <eliz@gnu.org> wrote:
> >
> > > From: Vincent Torri <vincent.torri@gmail.com>
> > > Date: Fri, 18 Aug 2023 08:41:05 +0200
> > > Cc: 65360@debbugs.gnu.org
> > >
> > > maybe it will be simpler for me to compile emacs and debug it directly
> > > with some printf(). At least i know where to look at now
> >
> > That can also be done, with the caveats that:
> >
> >   . to look at some variable, you will have to add code and recompile
> >     Emacs
>
> normally, make will recompile only what is needed, one file
>
> >   . if the function(s) in question are invoked frequently when you
> >     scroll, you will have a lot of output, without a good way of
> >     knowing which output was caused by which UI gesture
>
> well, there will not a lot of output : just scrolling once to the
> bottom is problematic
>
> > But that doesn't make printf-debugging impossible, so if it's easier
> > for you, let's try that!
>
> i'll inform you about what I get

- when I move two fingers from bottom to top of the touchpad, i get for example:
 * delta: -1
 * p 2227 x 1414

delta is always negative in that case

- when I move two fingers from top to bottom of the touchpad, i get for example:
 * delta: 4
 * p 2205 x 1336

delta is always positive in that case

I've also found that the function always exits in that test, in case it helps:

      if (eabs (sum_delta_y) < WHEEL_DELTA)
        {
          result->kind = NO_EVENT;
          return Qnil;
        }

Unrelated : you should check the warnings, at least on Windows,
because i've seen a NULL pointer dereference, and several use of
uninitialized variables

Vincent

bug#65360: emacs 29.1 with MSYS2: vertical scrolling with touchpad not working

[Vincent Torri]

hello

it is fixed in current git

thank you

Vincent Torri

bug#65360: emacs 29.1 with MSYS2: vertical scrolling with touchpad not working

[Eli Zaretskii]

> From: Vincent Torri <vincent.torri@gmail.com>
> Date: Sat, 26 Aug 2023 05:00:53 +0200
> Cc: 65360@debbugs.gnu.org
> 
> hello
> 
> it is fixed in current git

Thanks for testing, and for helping to diagnose the issue.  I'm
therefore closing this bug.