Mouse wheel release events?

Mouse wheel release events?

[Po Lu]

Some mouse wheels generate special events when the user moves his finger
off the wheel, even if the wheel was not previously clicked.

These events are used by most applications to start inertial scrolling,
support for which I would like to add to Emacs.

I want to add a `wheel-release' event that is sent every time Emacs
receives such an event from the mouse wheel.  Is that okay?

Thanks.

Re: Mouse wheel release events?

[Eli Zaretskii]

> From: Po Lu <luangruo@yahoo.com>
> Date: Tue, 30 Nov 2021 10:28:43 +0800
> 
> Some mouse wheels generate special events when the user moves his finger
> off the wheel, even if the wheel was not previously clicked.
> 
> These events are used by most applications to start inertial scrolling,
> support for which I would like to add to Emacs.
> 
> I want to add a `wheel-release' event that is sent every time Emacs
> receives such an event from the mouse wheel.  Is that okay?

Can you please point me to the technical description of such a mouse?

Re: Mouse wheel release events?

[Daniele Nicolodi]

On 30/11/2021 03:28, Po Lu wrote:
> Some mouse wheels generate special events when the user moves his finger
> off the wheel, even if the wheel was not previously clicked.
> 
> These events are used by most applications to start inertial scrolling,
> support for which I would like to add to Emacs.
> 
> I want to add a `wheel-release' event that is sent every time Emacs
> receives such an event from the mouse wheel.  Is that okay?

Which environment gives applications access to this kind of events? I 
think on (modernish) GNU/Linux these would be handled by libinput 
directly, relieving the application from the duty of handling these.

Cheers,
Dan

Re: Mouse wheel release events?

[Po Lu]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: Po Lu <luangruo@yahoo.com>
>> Date: Tue, 30 Nov 2021 10:28:43 +0800
>> 
>> Some mouse wheels generate special events when the user moves his finger
>> off the wheel, even if the wheel was not previously clicked.
>> 
>> These events are used by most applications to start inertial scrolling,
>> support for which I would like to add to Emacs.
>> 
>> I want to add a `wheel-release' event that is sent every time Emacs
>> receives such an event from the mouse wheel.  Is that okay?
>
> Can you please point me to the technical description of such a mouse?

I don't know how to find the technical description of a mouse, but here
is the XInput 2 documentation.  You should specifically look at the
section titled "Pointer emulation from multitouch events":

  https://www.x.org/releases/X11R7.7/doc/inputproto/XI2proto.txt

While the documentation makes it seem specific to touchpads, at least 2
kinds of mice, Apple's "Magic Mouse 2", and some Logitech mice with
"hyperscrolling" also generate events in that specific way.

Thanks.

Re: Mouse wheel release events?

[Po Lu]

Daniele Nicolodi <daniele@grinta.net> writes:

> On 30/11/2021 03:28, Po Lu wrote:
>> Some mouse wheels generate special events when the user moves his finger
>> off the wheel, even if the wheel was not previously clicked.
>> These events are used by most applications to start inertial
>> scrolling,
>> support for which I would like to add to Emacs.
>> I want to add a `wheel-release' event that is sent every time Emacs
>> receives such an event from the mouse wheel.  Is that okay?

> Which environment gives applications access to this kind of events? I
> think on (modernish) GNU/Linux these would be handled by libinput
> directly, relieving the application from the duty of handling these.

The X Input Extension generates special kinds of motion events along
with a whole class of touch events for this kind of device event.

It does not perform any further processing on them.

Re: Mouse wheel release events?

[Eli Zaretskii]

> From: Po Lu <luangruo@yahoo.com>
> Cc: emacs-devel@gnu.org
> Date: Wed, 01 Dec 2021 08:50:01 +0800
> 
> I don't know how to find the technical description of a mouse, but here
> is the XInput 2 documentation.  You should specifically look at the
> section titled "Pointer emulation from multitouch events":
> 
>   https://www.x.org/releases/X11R7.7/doc/inputproto/XI2proto.txt
> 
> While the documentation makes it seem specific to touchpads, at least 2
> kinds of mice, Apple's "Magic Mouse 2", and some Logitech mice with
> "hyperscrolling" also generate events in that specific way.

Regardless of which mice support these events, they (the events) are
touch events, not mouse events.  So I think we should name them as
such, because someone in the future might add support for the full
spectrum of touch events to Emacs.

So wheel-release doesn't strike me as a good name.  What kind of touch
event (or series of events) that emulates?

Re: Mouse wheel release events?

[Po Lu]

Eli Zaretskii <eliz@gnu.org> writes:

> Regardless of which mice support these events, they (the events) are
> touch events, not mouse events.  So I think we should name them as
> such, because someone in the future might add support for the full
> spectrum of touch events to Emacs.

We haven't explictly selected (asked the X server to send us) for
TouchEnded events, so what we receive is a special kind of motion event,
where the valuators are marked as modified, but there is no actual
change in valuator state.

> So wheel-release doesn't strike me as a good name.  What kind of touch
> event (or series of events) that emulates?

It's hard to tell.  With these mice, it is a single TouchEnd event, but
with a trackpad it could be a whole series of touch events.

Perhaps `touch-end' should suffice (specifically for the touch end
event, and not for the whole series of events, which we do not support
yet)?

Thanks.

Re: Mouse wheel release events?

[Eli Zaretskii]

> From: Po Lu <luangruo@yahoo.com>
> Cc: emacs-devel@gnu.org
> Date: Wed, 01 Dec 2021 21:31:14 +0800
> 
> Perhaps `touch-end' should suffice (specifically for the touch end
> event, and not for the whole series of events, which we do not support
> yet)?

Yes, touch-event should do for now.

Re: Mouse wheel release events?

[Po Lu]

Eli Zaretskii <eliz@gnu.org> writes:

>> Perhaps `touch-end' should suffice (specifically for the touch end
>> event, and not for the whole series of events, which we do not support
>> yet)?

> Yes, touch-event should do for now.

Thanks, I will add support for it now.