[PATCH wayland v4] protocol: Define further the behavior of input on the presence of grabs

Thu Jan 17 15:56:46 UTC 2019

On Thu, Jan 17, 2019 at 05:27:44PM +0200, Pekka Paalanen wrote:
> Hi all,
> 
> I noticed that this patch did not land yet. I added to CC everyone who
> commented on the v3 I believe.
> 
> Is this still relevant?

I'd say it's good clarifications, and making it possible to "leave"
touch points is still more correct than "up":ing or "cancel":ing them.

Just one minor comment about wording below.

> 
> 
> Thanks,
> pq
> 
> On Fri, 27 Jan 2017 18:46:58 +0100
> Carlos Garnacho <carlosg at gnome.org> wrote:
> 
> > The leave events in the respective device interfaces has been further
> > documented so those can convey the necessary info when input is being
> > redirected out of their currently focused surface.
> > 
> > Only wl_touch is missing something semantically similar, a wl_touch.leave
> > event has been added so the touch interface can cope with such input
> > redirection situations on individual touchpoints.
> > 
> > Signed-off-by: Carlos Garnacho <carlosg at gnome.org>
> > Reviewed-by: Peter Hutterer <peter.hutterer at who-t.net>
> > ---
> > 
> >  Changes since v3: Applied wording improvements from Yong Bakos, added
> >    the clarification suggested by Daniel, and made wl_touch.leave part of
> >    wl_touch.frame as suggested by Jonas (and that was the intended behavior).
> > 
> >    Also went ahead and bumped wl_seat version again to 7, since this is not
> >    1.13 material.
> > 
> >  protocol/wayland.xml | 68 ++++++++++++++++++++++++++++++++++++++++++++++++++--
> >  1 file changed, 66 insertions(+), 2 deletions(-)
> > 
> > diff --git a/protocol/wayland.xml b/protocol/wayland.xml
> > index 29b63be..7be23ec 100644
> > --- a/protocol/wayland.xml
> > +++ b/protocol/wayland.xml
> > @@ -1651,7 +1651,7 @@
> >      </request>
> >     </interface>
> >  
> > -  <interface name="wl_seat" version="6">
> > +  <interface name="wl_seat" version="7">
> >      <description summary="group of input devices">
> >        A seat is a group of keyboards, pointer and touch devices. This
> >        object is published as a global during start up, or when such a
> > @@ -1839,6 +1839,23 @@
> >  
> >  	The leave notification is sent before the enter notification
> >  	for the new focus.
> > +
> > +	While a pointer will not usually leave a surface while a button
> > +	is pressed, there are circumstances where this event may occur,
> > +	such as:
> > +
> > +	- When a popup is shown by this or another client.
> > +	- When a drag-and-drop operation is initiated from this or
> > +	  any other surface.
> > +	- Other compositor-specific grabs, like pointer gestures.
> > +
> > +	In these situations, a leave event will be emitted with no
> > +	paired button release event on this surface, and clients must
> > +	undo their internal state related to the ongoing button presses.
> > +
> > +	Clients must either receive a release or a leave event in a
> > +	timely manner, and strictly before all other input events from
> > +	that seat.

Clients can't "must" receive anything, a compositor either will or it
wont. Also is the "all other input evets from the seat" intentional? Or
should it be "all other pointer events from that seat"?

Jonas

> >        </description>
> >        <arg name="serial" type="uint" summary="serial number of the leave event"/>
> >        <arg name="surface" type="object" interface="wl_surface" summary="surface left by the pointer"/>
> > @@ -1880,6 +1897,10 @@
> >  	kernel's event code list. All other button codes above 0xFFFF are
> >  	currently undefined but may be used in future versions of this
> >  	protocol.
> > +
> > +	Clients should note that pressed/released events may not be paired;
> > +	in some cases, a leave event will be sent in place of a released event.
> > +	See wl_pointer.leave for more details.
> >        </description>
> >        <arg name="serial" type="uint" summary="serial number of the button event"/>
> >        <arg name="time" type="uint" summary="timestamp with millisecond granularity"/>
> > @@ -2127,6 +2148,17 @@
> >  
> >  	The leave notification is sent before the enter notification
> >  	for the new focus.
> > +
> > +	There may be circumstances that force the keyboard focus to be taken
> > +	away from a surface while there are pressed keys, for example:
> > +
> > +	- When a popup is shown by this or another client.
> > +	- When a drag-and-drop operation is initiated from this or
> > +	  any other surface.
> > +
> > +	In these situations, a leave event will be emitted with no paired
> > +	key release events on this surface, and clients must undo their
> > +	internal state related to the ongoing key presses.
> >        </description>
> >        <arg name="serial" type="uint" summary="serial number of the leave event"/>
> >        <arg name="surface" type="object" interface="wl_surface" summary="surface that lost keyboard focus"/>
> > @@ -2145,6 +2177,10 @@
> >  	A key was pressed or released.
> >  	The time argument is a timestamp with millisecond
> >  	granularity, with an undefined base.
> > +
> > +	Clients should note that pressed/released events may not be paired;
> > +	in some cases, a leave event will be sent in place of a released event.
> > +	See wl_keyboard.leave for more details.
> >        </description>
> >        <arg name="serial" type="uint" summary="serial number of the key event"/>
> >        <arg name="time" type="uint" summary="timestamp with millisecond granularity"/>
> > @@ -2194,7 +2230,7 @@
> >      </event>
> >    </interface>
> >  
> > -  <interface name="wl_touch" version="6">
> > +  <interface name="wl_touch" version="7">
> >      <description summary="touchscreen input device">
> >        The wl_touch interface represents a touchscreen
> >        associated with a seat.
> > @@ -2226,6 +2262,10 @@
> >  	The touch point has disappeared. No further events will be sent for
> >  	this touch point and the touch point's ID is released and may be
> >  	reused in a future touch down event.
> > +
> > +	Clients should note that down/up events may not be paired;
> > +	in some cases, a leave event will be sent in place of a wl_touch.up
> > +	event. See wl_touch.leave for more details.
> >        </description>
> >        <arg name="serial" type="uint" summary="serial number of the touch up event"/>
> >        <arg name="time" type="uint" summary="timestamp with millisecond granularity"/>
> > @@ -2336,6 +2376,30 @@
> >        <arg name="id" type="int" summary="the unique ID of this touch point"/>
> >        <arg name="orientation" type="fixed" summary="angle between major axis and positive surface y-axis in degrees"/>
> >      </event>
> > +
> > +    <!-- Version 7 additions -->
> > +
> > +    <event name="leave" since="7">
> > +      <description summary="leave event">
> > +	Notification that this touch point is no longer focused on a
> > +	certain surface. This event does not occur on its own. It is
> > +	sent before a wl_touch.frame event.
> > +
> > +	Note that, because touch points are always implicitly grabbed,
> > +	this event will only be emitted when the touch point is taken
> > +	away from this surface through explicit means, for example:
> > +
> > +	- When a popup is shown by this or another client.
> > +	- When a drag-and-drop operation is initiated from this or
> > +	  any other surface.
> > +
> > +	This event will only be emitted on objects of version 6 or
> > +	higher, older clients will receive a wl_touch.up event per
> > +	remaining touchpoint instead.
> > +      </description>
> > +      <arg name="surface" type="object" interface="wl_surface"/>
> > +      <arg name="id" type="int" summary="the unique ID of this touch point"/>
> > +    </event>
> >    </interface>
> >  
> >    <interface name="wl_output" version="3">
> 