On Wed, Jan 13, 2016 at 02:44:29PM +1000, Peter Hutterer wrote:
> On Wed, Jan 13, 2016 at 10:14:50AM +0800, Jonas Ådahl wrote:
> > This patch introduces a new protocol for locking and confining a
> > pointer. It consists of a new global object with two requests; one for
> > locking the surface to a position, one for confining the pointer to a
> > given region.
> > 
> > Signed-off-by: Jonas Ådahl <[email protected]>
> > Reviewed-by: Peter Hutterer <[email protected]>
> > Reviewed-by: Derek Foreman <[email protected]>
> > ---
> > 
> > Changes since v2:
> > 
> > Added a "lifetime" enum which is passed to the locking/confining requests. 
> > It
> > is used to specify whether the constraints should be oneshot or reoccurring.
> > Oneshot and reoccurring both has race conditions when they are deactivated, 
> > and
> > this enables the client to choose what race condition it prefers.
> > 
> > The oneshot race condition is that client may not be able to re-request the
> > constraint in time, and as a result will loose the constraint where it 
> > should
> > not have.
> > 
> > The reoccurring race condition is that the client may not be able to destroy
> > the constraint in time, and as a result the compositor will re-constrain the
> > pointer when it shouldn't.
> > 
> > Whether each of these race conditions are preferrable depends on the
> > application using them, so lets give the client the option to choose.
> > 
> > 
> > Another change is that the factory requests now take a wl_pointer instead 
> > of a
> > wl_seat.
> > 
> > 
> > Jonas
> > 
> > 
> >  Makefile.am                                        |   1 +
> >  unstable/pointer-constraints/README                |   4 +
> >  .../pointer-constraints-unstable-v1.xml            | 341 
> > +++++++++++++++++++++
> >  3 files changed, 346 insertions(+)
> >  create mode 100644 unstable/pointer-constraints/README
> >  create mode 100644 
> > unstable/pointer-constraints/pointer-constraints-unstable-v1.xml
> > 
> > diff --git a/Makefile.am b/Makefile.am
> > index e3b60ad..44041a6 100644
> > --- a/Makefile.am
> > +++ b/Makefile.am
> > @@ -6,6 +6,7 @@ unstable_protocols =                                        
> >                         \
> >     unstable/input-method/input-method-unstable-v1.xml                      
> > \
> >     unstable/xdg-shell/xdg-shell-unstable-v5.xml                            
> > \
> >     unstable/relative-pointer/relative-pointer-unstable-v1.xml              
> > \
> > +   unstable/pointer-constraints/pointer-constraints-unstable-v1.xml        
> > \
> >     $(NULL)
> >  
> >  nobase_dist_pkgdata_DATA =                                                 
> > \
> > diff --git a/unstable/pointer-constraints/README 
> > b/unstable/pointer-constraints/README
> > new file mode 100644
> > index 0000000..8a242f8
> > --- /dev/null
> > +++ b/unstable/pointer-constraints/README
> > @@ -0,0 +1,4 @@
> > +Pointer constraints protocol
> > +
> > +Maintainers:
> > +Jonas Ådahl <[email protected]>
> > diff --git 
> > a/unstable/pointer-constraints/pointer-constraints-unstable-v1.xml 
> > b/unstable/pointer-constraints/pointer-constraints-unstable-v1.xml
> > new file mode 100644
> > index 0000000..607a538
> > --- /dev/null
> > +++ b/unstable/pointer-constraints/pointer-constraints-unstable-v1.xml
> > @@ -0,0 +1,341 @@
> > +<?xml version="1.0" encoding="UTF-8"?>
> > +<protocol name="pointer_constraints_unstable_v1">
> > +
> > +  <copyright>
> > +    Copyright © 2014      Jonas Ådahl
> > +    Copyright © 2015      Red Hat Inc.
> > +
> > +    Permission is hereby granted, free of charge, to any person obtaining a
> > +    copy of this software and associated documentation files (the 
> > "Software"),
> > +    to deal in the Software without restriction, including without 
> > limitation
> > +    the rights to use, copy, modify, merge, publish, distribute, 
> > sublicense,
> > +    and/or sell copies of the Software, and to permit persons to whom the
> > +    Software is furnished to do so, subject to the following conditions:
> > +
> > +    The above copyright notice and this permission notice (including the 
> > next
> > +    paragraph) shall be included in all copies or substantial portions of 
> > the
> > +    Software.
> > +
> > +    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 
> > EXPRESS OR
> > +    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF 
> > MERCHANTABILITY,
> > +    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT 
> > SHALL
> > +    THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR 
> > OTHER
> > +    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
> > +    FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
> > +    DEALINGS IN THE SOFTWARE.
> > +  </copyright>
> > +
> > +  <description summary="Protocol for constraining pointer motions">
> > +    This protocol specifies a set of interfaces used for adding 
> > constraints to
> > +    the motion of a pointer. Possible constraints include confining pointer
> > +    motions to a given region, or locking it to its current position.
> > +
> > +    In order to contrain the pointer, a client must first bind the global
> > +    interface "wp_pointer_constraints" which, if a compositor supports 
> > pointer
> > +    constraints, is exposed by the registry. Using the bound global 
> > object, the
> > +    client uses the request that corresponds to the type of constraint it 
> > wants
> > +    to make. See wp_pointer_constraints for more details.
> > +
> > +    Warning! The protocol described in this file is experimental and 
> > backward
> > +    incompatible changes may be made. Backward compatible changes may be 
> > added
> > +    together with the corresponding interface version bump.  Backward
> > +    incompatible changes are done by bumping the version number in the 
> > protocol
> > +    and interface names and resetting the interface version.  Once the 
> > protocol
> > +    is to be declared stable, the 'z' prefix and the version number in the
> > +    protocol and interface names are removed and the interface version 
> > number is
> > +    reset.
> > +  </description>
> > +
> > +  <interface name="zwp_pointer_constraints_v1" version="1">
> > +    <description summary="constrain the movement of a pointer">
> > +      The global interface exposing pointer constraining functionality. It
> > +      exposes two requests; lock_pointer for locking the pointer to its
> > +      position, and confine_pointer for locking the pointer to a region.
> > +
> > +      The lock_pointer and confine_pointer requests create the objects
> > +      wp_locked_pointer and wp_confined_pointer respectively, and the 
> > client can
> > +      use these objects to interact with the lock.
> > +
> > +      For any surface, only one lock or confinement per seat may be active 
> > at
> > +      any time. If a lock or confinement is requested when another lock or
> > +      confinement is active or requested on that surface and seat, an
> > +      'already_constrained' error will be raised.
> 
> should this read as "pointer" instead of seat now?

This paragraph is now changed to:

      For any surface, only one lock or confinement may be active across all
      wl_pointer objects of the same seat. If a lock or confinement is requested
      when another lock or confinement is active or requested on the same 
surface
      and with any of the wl_pointer objects of the same seat, an
      'already_constrained' error will be raised.

> 
> > +    </description>
> > +
> > +    <enum name="error">
> > +      <description summary="wp_pointer_constraints error values">
> > +   These errors can be emitted in response to wp_pointer_constraints
> > +   requests.
> > +      </description>
> > +      <entry name="already_constrained" value="1"
> > +        summary="pointer constraint already requested on that surface"/>
> > +    </enum>
> > +
> > +    <enum name="lifetime">
> > +      <description summary="constraint lifetime">
> > +   These values represent different lifetime semantics. They are passed
> > +   as argument to the factory requests to specify how the constraint
> > +   lifetimes should be managed.
> > +      </description>
> > +      <entry name="oneshot" value="1">
> > +   <description summary="the pointer constraint is defunct once 
> > deactivated">
> > +     A oneshot pointer constraint will never re-activate once it has been
> > +     deactivated. See the corresponding deactivation event
> > +     (wp_locked_pointer.unlocked and wp_confined_pointer.unconfined) for
> > +     details.
> > +   </description>
> > +      </entry>
> > +      <entry name="reoccurring" value="2">
> 
> drop the 'o', this should be "recurring", goes for all uses of the word
> below.

Hmm. I guess so. What I can see about the difference between reoccurring
and recurring is that recurring means occurring again at a regular
interval, while reoccurring means maybe occurring again at an irregular
interval. So is recurring really correct?

> 
> > +   <description summary="the pointer constraint is defunct once 
> > deactivated">
> 
> and this should be a bit different to the oneshot :)

Changed to "the pointer constraint is may reactivate"

> 
> > +     A reoccurring pointer constraint may again re-activate once it has
> > +     been deactivated. See the corresponding deactivation event
> 
> if deactivate doesn't get a -, reactivate shouldn't either.

Fixed locally.

> 
> > +     (wp_locked_pointer.unlocked and wp_confined_pointer.unconfined) for
> > +     details.
> > +   </description>
> > +      </entry>
> > +    </enum>
> > +
> > +    <request name="destroy" type="destructor">
> > +      <description summary="destroy the pointer constraints manager 
> > object">
> > +   Used by the client to notify the server that it will no longer use this
> > +   pointer constraints object.
> > +      </description>
> > +    </request>
> > +
> > +    <request name="lock_pointer">
> > +      <description summary="lock pointer to a position">
> > +   The lock_pointer request lets the client request to disable movements of
> > +   the virtual pointer (i.e. the cursor), effectively locking the pointer
> > +   to a position. This request may not take effect immediately; in the
> > +   future, when the compositor deems implementation-specific constraints
> > +   are satisfied, the pointer lock will be activated and the compositor
> > +   sends a locked event.
> > +
> > +   The protocol provides no guarantee that the constraints are ever
> > +   satisfied, and does not require the compositor to send an error if the
> > +   constraints cannot ever be satisfied. It is thus possible to request a
> > +   lock that will never activate.
> > +
> > +   There may not be another lock of any kind requested or active on the
> > +   surface for the seat of the given pointer when requesting a lock. If
> > +   there is, an error will be raised. See general pointer lock
> > +   documentation for more details.
> 
> needs a seat/pointer rewording

This paragraph is now:

        There may not be another pointer constraint of any kind requested or
        active on the surface for any of the wl_pointer objects of the seat of
        the passed pointer when requesting a lock. If there is, an error will be
        raised. See general pointer lock documentation for more details.

> 
> > +
> > +   The intersection of the region passed with this request and the input
> > +   region of the surface is used to determine where the pointer must be
> > +   in order for the lock to activate. It is up to the compositor whether to
> > +   warp the pointer or require some kind of user interaction for the lock
> > +   to activate. If the region is null the surface input region is used.
> > +
> > +   A surface may receive pointer focus without the lock being activated.
> > +
> > +   The request will create a new object wp_locked_pointer which is used to
> 
> s/will create/creates/

Fixed locally.

> 
> > +   interact with the lock as well as receive updates about its state. See
> > +   the the description of wp_locked_pointer for further information.
> > +
> > +   Note that while a pointer is locked, the wl_pointer objects of the
> > +   corresponding seat will not emit any wl_pointer.motion events, but
> > +   relative motion events will still be emitted via wp_relative_pointer
> > +   objects of the same seat. wl_pointer.axis and wl_pointer.button events
> > +   are unaffected.
> > +      </description>
> > +
> > +      <arg name="id" type="new_id" interface="zwp_locked_pointer_v1"/>
> > +      <arg name="surface" type="object" interface="wl_surface"
> > +      summary="surface to lock pointer to"/>
> > +      <arg name="pointer" type="object" interface="wl_pointer"
> > +      summary="the pointer that should be locked"/>
> > +      <arg name="region" type="object" interface="wl_region" 
> > allow-null="true"
> > +      summary="region of surface"/>
> > +      <arg name="lifetime" type="uint" summary="lock lifetime"/>
> > +    </request>
> > +
> > +    <request name="confine_pointer">
> > +      <description summary="confine pointer to a region">
> > +   The confine_pointer request lets the client request to confine the
> > +   pointer cursor to a given region. This request may not take effect
> > +   immediately; in the future, when the compositor deems implementation-
> > +   specific constraints are satisfied, the pointer confinement will be
> > +   activated and the compositor sends a confined event.
> > +
> > +   The intersection of the region passed with this request and the input
> > +   region of the surface is used to determine where the pointer must be
> > +   in order for the confinement to activate. It is up to the compositor
> > +   whether to warp the pointer or require some kind of user interaction for
> > +   the confinement to activate. If the region is null the surface input
> > +   region is used.
> > +
> > +   The request will create a new object wp_confined_pointer which is used
> > +   to interact with the confinement as well as receive updates about its
> > +   state. See the the description of wp_confined_pointer for further
> > +   information.
> > +      </description>
> > +
> > +      <arg name="id" type="new_id" interface="zwp_confined_pointer_v1"/>
> > +      <arg name="surface" type="object" interface="wl_surface"
> > +      summary="surface to lock pointer to"/>
> > +      <arg name="pointer" type="object" interface="wl_pointer"
> > +      summary="the pointer that should be confined"/>
> > +      <arg name="region" type="object" interface="wl_region" 
> > allow-null="true"
> > +      summary="region of surface"/>
> > +      <arg name="lifetime" type="uint" summary="confinement lifetime"/>
> > +    </request>
> > +  </interface>
> > +
> > +  <interface name="zwp_locked_pointer_v1" version="1">
> > +    <description summary="receive relative pointer motion events">
> > +      The wp_locked_pointer interface represents a locked pointer state.
> > +
> > +      While the lock of this object is active, the wl_pointer objects of 
> > the
> > +      associated seat will not emit any wl_pointer.motion events.
> > +
> > +      This object will send the event 'locked' when the lock is activated.
> > +      Whenever the lock is activated, it is guaranteed that the locked 
> > surface
> > +      will already have received pointer focus and that the pointer will be
> > +      within the region passed to the request creating this object.
> > +
> > +      To unlock the pointer, send the destroy request. This will also 
> > destroy
> > +      the wp_locked_pointer object.
> > +
> > +      If the compositor decides to unlock the pointer the unlocked event is
> > +      sent. The wp_locked_pointer object is at this point defunct and 
> > should be
> > +      destroyed.
> 
> needs updates for the lifetime, or just a reference to the unlocked event
> documentation.

Fixed by just referencing .unlocked.

> 
> > +
> > +      When unlocking, the compositor may warp the cursor position to the 
> > set
> > +      cursor position hint. If it does, it will not result in any relative
> > +      motion events emitted via wp_relative_pointer.
> > +
> > +      If the surface the lock was requested on is destroyed and the lock 
> > is not
> > +      yet activated, the wp_locked_pointer object is now defunct and must 
> > be
> > +      destroyed.
> > +    </description>
> > +
> > +    <request name="destroy" type="destructor">
> > +      <description summary="destroy the locked pointer object">
> > +   Destroy the locked pointer object. If applicable, the compositor will
> > +   unlock the pointer.
> > +      </description>
> > +    </request>
> > +
> > +    <request name="set_cursor_position_hint">
> > +      <description summary="set the pointer cursor position hint">
> > +   Set the cursor position hint relative to the top left corner of the
> > +   surface.
> > +
> > +   If the client is drawing its own cursor, it should update the position
> > +   hint to the position of its own cursor. A compositor may use this
> > +   information to warp the pointer upon unlock in order to avoid pointer
> > +   jumps.
> > +
> > +   The cursor position hint is double buffered. The new hint will only take
> > +   effect when the associated surface gets it pending state applied. See
> > +   wl_surface.commit for details.
> > +      </description>
> > +
> > +      <arg name="surface_x" type="fixed"
> > +      summary="x coordinate in surface-relative coordinates"/>
> > +      <arg name="surface_y" type="fixed"
> > +      summary="y coordinate in surface-relative coordinates"/>
> > +    </request>
> > +
> > +    <request name="set_region">
> > +      <description summary="set a new lock region">
> > +   Set a new region used to lock the pointer.
> > +
> > +   The new lock region is double-buffered. The new lock region will
> > +   only take effect when the associated surface gets its pending state
> > +   applied. See wl_surface.commit for details.
> > +
> > +   For details about the lock region, see wp_locked_pointer.
> > +      </description>
> > +
> > +      <arg name="region" type="object" interface="wl_region" 
> > allow-null="true"
> > +      summary="region of surface"/>
> > +    </request>
> > +
> > +    <event name="locked">
> > +      <description summary="lock activation event">
> > +   Notification that the pointer lock of the seat's pointer is activated.
> > +      </description>
> > +    </event>
> > +
> > +    <event name="unlocked">
> > +      <description summary="lock deactivation event">
> > +   Notification that the pointer lock of the seat's pointer is no longer
> > +   active. If this is a oneshot pointer lock (see
> > +   wp_pointer_constraints.lifetime) this object is now defunct and should
> > +   be destroyed. If this is a reoccurring pointer lock (see
> > +   wp_pointer_constraints.lifetime) this the pointer lock may again
> > +   reactivate in the future.
> > +      </description>
> > +    </event>
> > +  </interface>
> > +
> > +  <interface name="zwp_confined_pointer_v1" version="1">
> > +    <description summary="confined pointer object">
> > +      The wp_confined_pointer interface represents a confined pointer 
> > state.
> > +
> > +      This object will send the event 'confined' when the confinement is
> > +      activated. Whenever the confinement is activated, it is guaranteed 
> > that
> > +      the surface the pointer is confined to will already have received 
> > pointer
> > +      focus and that the pointer will be within the region passed to the 
> > request
> > +      creating this object. It is up to the compositor to decide whether 
> > this
> > +      requires some user interaction and if the pointer will warp to 
> > within the
> > +      passed region if outside.
> > +
> > +      To unconfine the pointer, send the destroy request. This will also 
> > destroy
> > +      the wp_confined_pointer object.
> > +
> > +      If the compositor decides to unconfine the pointer the unconfined 
> > event is
> > +      sent. The wp_confined_pointer object is at this point defunct and 
> > should
> > +      be destroyed.
> > +    </description>
> > +
> > +    <request name="destroy" type="destructor">
> > +      <description summary="destroy the confined pointer object">
> > +   Destroy the confined pointer object. If applicable, the compositor will
> > +   unconfine the pointer.
> > +      </description>
> > +    </request>
> > +
> > +    <request name="set_region">
> > +      <description summary="set a new confine region">
> > +   Set a new region used to confine the pointer.
> > +
> > +   The new confine region is double-buffered. The new confine region will
> > +   only take effect when the associated surface gets its pending state
> > +   applied. See wl_surface.commit for details.
> > +
> > +   If the confinement is active when the new confinement region is applied
> > +   and the pointer ends up outside of newly applied region, the pointer is
> > +   warped to a position within the new confinement region. If warped, a
> > +   wl_pointer.motion event will be emitted, but no
> > +   wp_relative_pointer.relative_motion event.
> 
> is there a case where the compositor will break the confinement if it's not
> happy with the new region? If so, we should add a comment here to state
> that.

Hmm. I suppose a 0x0 region would be hard to make any sense of. I guess we can
add a blurb about that an effective 0x0 region (intersection between set region
and input region is 0x0) would result in an unconfined event.

Something like:

        If the effective confinement region (the intersection of the applied
        confinement region and the input region of the corresponding wl_surface)
        is empty, an active confinement would be deactivated.

maybe?

> 
> my rev-by still stands.

Thanks!


Jonas

> 
> Cheers,
>    Peter
> 
> > +
> > +   For details about the confine region, see wp_confined_pointer.
> > +      </description>
> > +
> > +      <arg name="region" type="object" interface="wl_region" 
> > allow-null="true"
> > +      summary="region of surface"/>
> > +    </request>
> > +
> > +    <event name="confined">
> > +      <description summary="pointer confined">
> > +   Notification that the pointer confinement of the seat's pointer is
> > +   activated.
> > +      </description>
> > +    </event>
> > +
> > +    <event name="unconfined">
> > +      <description summary="pointer unconfined">
> > +   Notification that the pointer confinement of the seat's pointer is no
> > +   longer active. If this is a oneshot pointer confinement (see
> > +   wp_pointer_constraints.lifetime) this object is now defunct and should
> > +   be destroyed. If this is a reoccurring pointer confinement (see
> > +   wp_pointer_constraints.lifetime) this the pointer confinement may again
> > +   reactivate in the future.
> > +      </description>
> > +    </event>
> > +  </interface>
> > +
> > +</protocol>
> > -- 
> > 2.4.3
> > 
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