bug#65129: 30.0.50; pinch gestures suddenly stops being recognised

bug#65129: 30.0.50; pinch gestures suddenly stops being recognised

[Visuwesh]

Unfortunately, I don't have a good reproducer for this but ever since
updating to master from the emacs-29 branch, pinch gestures in Emacs
frames suddenly stops being recognised.  When I do C-h k and pinch, or
view lossage, I see wheel-left and wheel-down events but no pinch event.

However, if I create a new frame and try to pinch there, it works just
fine.

I apologise again for the vague report, but I have nothing better to
offer.  So far, I haven't tried to reproduce this in an emacs -Q
session.

In GNU Emacs 30.0.50 (build 4, x86_64-pc-linux-gnu, X toolkit, Xaw
 scroll bars) of 2023-08-04 built on astatine
Repository revision: 92f9d2b43e1974bf1496e436ad49d3b687ee0d3f
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.12101007
System Description: Debian GNU/Linux trixie/sid

Configured using:
 'configure --with-sound=alsa --with-x-toolkit=lucid --with-json
 --without-xaw3d --without-gconf --without-libsystemd --without-cairo'
Configured features:
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XIM XINPUT2 XPM LUCID ZLIB
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  value of $LC_NUMERIC: ta_IN.UTF-8
  value of $LANG: en_GB.UTF-8
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Major mode: Article

Minor modes in effect:
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Load-path shadows:
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bug#65129: 30.0.50; pinch gestures suddenly stops being recognised

[Po Lu via Bug reports for GNU Emacs, the Swiss army knife of text editors]

Visuwesh <visuweshm@gmail.com> writes:

> Unfortunately, I don't have a good reproducer for this but ever since
> updating to master from the emacs-29 branch, pinch gestures in Emacs
> frames suddenly stops being recognised.  When I do C-h k and pinch, or
> view lossage, I see wheel-left and wheel-down events but no pinch event.
>
> However, if I create a new frame and try to pinch there, it works just
> fine.
>
> I apologise again for the vague report, but I have nothing better to
> offer.  So far, I haven't tried to reproduce this in an emacs -Q
> session.

No worries there, please instrument handle_one_xevent like so:

diff --git a/src/xterm.c b/src/xterm.c
index f454733c659..57b06c571f6 100644
--- a/src/xterm.c
+++ b/src/xterm.c
@@ -24722,6 +24722,11 @@ handle_one_xevent (struct x_display_info *dpyinfo,
 	      x_display_set_last_user_time (dpyinfo, pev->time,
 					    pev->send_event, true);
 
+	      if (device)
+		fprintf (stderr, "XI_GesturePinchBegin: %d\n", device->use);
+	      else
+		fprintf (stderr, "XI_GesturePinchBegin: no device\n");
+
 	      if (!device || device->use != XIMasterPointer)
 		goto XI_OTHER;
 
and show us what is printed when you attempt a pinch gesture after they
cease being delivered.

bug#65129: 30.0.50; pinch gestures suddenly stops being recognised

[Visuwesh]

[Tuesday August 08, 2023] Po Lu wrote:

> No worries there, please instrument handle_one_xevent like so:
>
> diff --git a/src/xterm.c b/src/xterm.c
> index f454733c659..57b06c571f6 100644
> --- a/src/xterm.c
> +++ b/src/xterm.c
> @@ -24722,6 +24722,11 @@ handle_one_xevent (struct x_display_info *dpyinfo,
>  	      x_display_set_last_user_time (dpyinfo, pev->time,
>  					    pev->send_event, true);
>  
> +	      if (device)
> +		fprintf (stderr, "XI_GesturePinchBegin: %d\n", device->use);
> +	      else
> +		fprintf (stderr, "XI_GesturePinchBegin: no device\n");
> +
>  	      if (!device || device->use != XIMasterPointer)
>  		goto XI_OTHER;
>  
> and show us what is printed when you attempt a pinch gesture after they
> cease being delivered.

I see nothing being printed once pinch gestures stop being recognised.
I see XI_GesturePinchBegin: 1 a whole bunch of times when they still
work though.
I confirmed that it is printed once again by opening a new frame and
trying the gesture there once it ceased recognised in the original
frame.

P.S., to confirm that I did apply the patch correctly, this is under
"case XI_GesturePinchUpdate:" under handle_one_xevent function right?
When I tried C-c C-a from a diff buffer, I got prompted

    Try to auto-fix whitespace loss? (y or n)

(to which I said yes) so I am not so confident that the patch applied
correctly.

bug#65129: 30.0.50; pinch gestures suddenly stops being recognised

[Po Lu via Bug reports for GNU Emacs, the Swiss army knife of text editors]

Visuwesh <visuweshm@gmail.com> writes:

> I see nothing being printed once pinch gestures stop being recognised.
> I see XI_GesturePinchBegin: 1 a whole bunch of times when they still
> work though.
> I confirmed that it is printed once again by opening a new frame and
> trying the gesture there once it ceased recognised in the original
> frame.

Yes, thanks.

> P.S., to confirm that I did apply the patch correctly, this is under
> "case XI_GesturePinchUpdate:" under handle_one_xevent function right?
> When I tried C-c C-a from a diff buffer, I got prompted
>
>     Try to auto-fix whitespace loss? (y or n)
>
> (to which I said yes) so I am not so confident that the patch applied
> correctly.

Does gesture recognition cease immediately subsequent to displaying a
toolkit menu?

Thanks.

bug#65129: 30.0.50; pinch gestures suddenly stops being recognised

[Visuwesh]

[Wednesday August 09, 2023] Po Lu via "Bug reports for GNU Emacs, the Swiss army knife of text editors" wrote:

>> P.S., to confirm that I did apply the patch correctly, this is under
>> "case XI_GesturePinchUpdate:" under handle_one_xevent function right?
>> When I tried C-c C-a from a diff buffer, I got prompted
>>
>>     Try to auto-fix whitespace loss? (y or n)
>>
>> (to which I said yes) so I am not so confident that the patch applied
>> correctly.
>
> Does gesture recognition cease immediately subsequent to displaying a
> toolkit menu?

Yes, you are right!

> Thanks.

bug#65129: 30.0.50; pinch gestures suddenly stops being recognised

[Po Lu via Bug reports for GNU Emacs, the Swiss army knife of text editors]

Visuwesh <visuweshm@gmail.com> writes:

> [Wednesday August 09, 2023] Po Lu via "Bug reports for GNU Emacs, the Swiss army knife of text editors" wrote:
>
>>> P.S., to confirm that I did apply the patch correctly, this is under
>>> "case XI_GesturePinchUpdate:" under handle_one_xevent function right?
>>> When I tried C-c C-a from a diff buffer, I got prompted
>>>
>>>     Try to auto-fix whitespace loss? (y or n)
>>>
>>> (to which I said yes) so I am not so confident that the patch applied
>>> correctly.
>>
>> Does gesture recognition cease immediately subsequent to displaying a
>> toolkit menu?
>
> Yes, you are right!
>
>> Thanks.

Does the following patch fix your problem?

diff --git a/src/xmenu.c b/src/xmenu.c
index 6d32aa3e078..d4b5b385e11 100644
--- a/src/xmenu.c
+++ b/src/xmenu.c
@@ -1680,6 +1680,19 @@ leave_toolkit_menu (void *data)
   XISetMask (m, XI_Enter);
   XISetMask (m, XI_Leave);
 
+#ifdef HAVE_XINPUT2_4
+  /* Select for gesture events.  Emacs selects for gesture events from
+     all master devices on non-GTK3 builds, so that event mask is also
+     clobbered by prepare_for_entry_into_toolkit_menu.  (bug#65129) */
+
+  if (dpyinfo->xi2_version >= 4)
+    {
+      XISetMask (m, XI_GesturePinchBegin);
+      XISetMask (m, XI_GesturePinchUpdate);
+      XISetMask (m, XI_GesturePinchEnd);
+    }
+#endif /* HAVE_XINPUT2_4 */
+
   FOR_EACH_FRAME (tail, frame)
     {
       f = XFRAME (frame);

bug#65129: 30.0.50; pinch gestures suddenly stops being recognised

[Visuwesh]

[Wednesday August 09, 2023] Po Lu wrote:

> Does the following patch fix your problem?

Yes, it does.  Thanks!

> diff --git a/src/xmenu.c b/src/xmenu.c
> index 6d32aa3e078..d4b5b385e11 100644
> --- a/src/xmenu.c
> +++ b/src/xmenu.c
> @@ -1680,6 +1680,19 @@ leave_toolkit_menu (void *data)
>    XISetMask (m, XI_Enter);
>    XISetMask (m, XI_Leave);
>  
> +#ifdef HAVE_XINPUT2_4
> +  /* Select for gesture events.  Emacs selects for gesture events from
> +     all master devices on non-GTK3 builds, so that event mask is also
> +     clobbered by prepare_for_entry_into_toolkit_menu.  (bug#65129) */
> +
> +  if (dpyinfo->xi2_version >= 4)
> +    {
> +      XISetMask (m, XI_GesturePinchBegin);
> +      XISetMask (m, XI_GesturePinchUpdate);
> +      XISetMask (m, XI_GesturePinchEnd);
> +    }
> +#endif /* HAVE_XINPUT2_4 */
> +
>    FOR_EACH_FRAME (tail, frame)
>      {
>        f = XFRAME (frame);

bug#65129: 30.0.50; pinch gestures suddenly stops being recognised

[Po Lu via Bug reports for GNU Emacs, the Swiss army knife of text editors]

Visuwesh <visuweshm@gmail.com> writes:

> [Wednesday August 09, 2023] Po Lu wrote:
>
>> Does the following patch fix your problem?
>
> Yes, it does.  Thanks!
>
>> diff --git a/src/xmenu.c b/src/xmenu.c
>> index 6d32aa3e078..d4b5b385e11 100644
>> --- a/src/xmenu.c
>> +++ b/src/xmenu.c
>> @@ -1680,6 +1680,19 @@ leave_toolkit_menu (void *data)
>>    XISetMask (m, XI_Enter);
>>    XISetMask (m, XI_Leave);
>>  
>> +#ifdef HAVE_XINPUT2_4
>> +  /* Select for gesture events.  Emacs selects for gesture events from
>> +     all master devices on non-GTK3 builds, so that event mask is also
>> +     clobbered by prepare_for_entry_into_toolkit_menu.  (bug#65129) */
>> +
>> +  if (dpyinfo->xi2_version >= 4)
>> +    {
>> +      XISetMask (m, XI_GesturePinchBegin);
>> +      XISetMask (m, XI_GesturePinchUpdate);
>> +      XISetMask (m, XI_GesturePinchEnd);
>> +    }
>> +#endif /* HAVE_XINPUT2_4 */
>> +
>>    FOR_EACH_FRAME (tail, frame)
>>      {
>>        f = XFRAME (frame);

I'll install this shortly, and am closing this bug.