[PATCH v3 wayland] protocol: specify behavior of get_pointer when capabilities change

[Bill Spitzak]

Again I don't understand why you think it is important to include all this
confusing text.

If I am not mistaken, *some* compositors less than version 5 do *NOT* act
in the old way.

Therefore no client can rely on this behaviour even if the compositor is
less than verison 5. And people writing compositors I think should be
encouraged to write the newest version api. So this text is irrelevant for
everybody.

I really would just delete all this text. You want to require clients to
monitor the capability events and destroy/create the wl_pointer in
response, so just say that. Stop giving them ways to get around what you
want.

I'm not sure if it is possible, but you might want to change creation of
wl_pointer before the capability is received into an error. I would suspect
a lot of clients create the wl_seat and then immediately create the
wl_pointer (and wl_keyboard, etc) without waiting for anything. This is
technically wrong, and probably a good indicator of a client that will also
fail to destroy/recreate the wl_pointer correctly.


On Sun, Dec 6, 2015 at 11:29 PM, Jonas Ådahl <jadahl at gmail.com> wrote:

> On Mon, Dec 07, 2015 at 03:43:35PM +1000, Peter Hutterer wrote:
> > Also applies to touch/keyboard
> >
> > Signed-off-by: Peter Hutterer <peter.hutterer at who-t.net>
>
> Looks good to me now, so consider this Reviewed-by: Jonas Ådahl
> <jadahl at gmail.com>
>
>
> Jonas
>
> > ---
> > Changes to v1:
> > - reword the paragraph detailing the pre v5 behaviour
> >
> >  protocol/wayland.xml | 33 ++++++++++++++++++++++++++++++---
> >  1 file changed, 30 insertions(+), 3 deletions(-)
> >
> > diff --git a/protocol/wayland.xml b/protocol/wayland.xml
> > index 7ca5049..df8ed19 100644
> > --- a/protocol/wayland.xml
> > +++ b/protocol/wayland.xml
> > @@ -1396,6 +1396,27 @@
> >       This is emitted whenever a seat gains or loses the pointer,
> >       keyboard or touch capabilities.  The argument is a capability
> >       enum containing the complete set of capabilities this seat has.
> > +
> > +     When the pointer capability is added, a client may create a
> > +     wl_pointer object using the wl_seat.get_pointer request. This
> object
> > +     will receive pointer events until the capability is removed in the
> > +     future.
> > +
> > +     When the pointer capability is removed, a client should destroy the
> > +     wl_pointer objects associated with the seat where the capability
> was
> > +     removed, using the wl_pointer.release request. No further pointer
> > +     events will be received on these objects.
> > +
> > +     In some compositors, if a seat regains the pointer capability and a
> > +     client has a previously obtained wl_pointer object of version 4 or
> > +     less, that object may start sending pointer events again. This
> > +     behavior is considered a misinterpretation of the intended behavior
> > +     and must not be relied upon by the client. wl_pointer objects of
> > +     version 5 or later must not send events if created before the most
> > +     recent event notifying the client of an added pointer capability.
> > +
> > +     The above behavior also applies to wl_keyboard and wl_touch with
> the
> > +     keyboard and touch capabilities, respectively.
> >        </description>
> >        <arg name="capabilities" type="uint" enum="capability"/>
> >      </event>
> > @@ -1406,7 +1427,9 @@
> >       for this seat.
> >
> >       This request only takes effect if the seat has the pointer
> > -     capability.
> > +     capability, or has had the pointer capability in the past.
> > +     It is a protocol violation to issue this request on a seat that has
> > +     never had the pointer capability.
> >        </description>
> >        <arg name="id" type="new_id" interface="wl_pointer"/>
> >      </request>
> > @@ -1417,7 +1440,9 @@
> >       for this seat.
> >
> >       This request only takes effect if the seat has the keyboard
> > -     capability.
> > +     capability, or has had the keyboard capability in the past.
> > +     It is a protocol violation to issue this request on a seat that has
> > +     never had the keyboard capability.
> >        </description>
> >        <arg name="id" type="new_id" interface="wl_keyboard"/>
> >      </request>
> > @@ -1428,7 +1453,9 @@
> >       for this seat.
> >
> >       This request only takes effect if the seat has the touch
> > -     capability.
> > +     capability, or has had the touch capability in the past.
> > +     It is a protocol violation to issue this request on a seat that has
> > +     never had the touch capability.
> >        </description>
> >        <arg name="id" type="new_id" interface="wl_touch"/>
> >      </request>
> > --
> > 2.5.0
> >
>
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