--- /dev/null
+<?xml version="1.0" encoding="UTF-8"?>
+<protocol name="subsurface">
+
+ <copyright>
+ Copyright © 2012-2013 Collabora, Ltd.
+
+ Permission to use, copy, modify, distribute, and sell this
+ software and its documentation for any purpose is hereby granted
+ without fee, provided that the above copyright notice appear in
+ all copies and that both that copyright notice and this permission
+ notice appear in supporting documentation, and that the name of
+ the copyright holders not be used in advertising or publicity
+ pertaining to distribution of the software without specific,
+ written prior permission. The copyright holders make no
+ representations about the suitability of this software for any
+ purpose. It is provided "as is" without express or implied
+ warranty.
+
+ THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS
+ SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ FITNESS, IN NO EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY
+ SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
+ AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
+ ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
+ THIS SOFTWARE.
+ </copyright>
+
+ <interface name="wl_subcompositor" version="1">
+ <description summary="sub-surface compositing">
+ The global interface exposing sub-surface compositing capabilities.
+ A wl_surface, that has sub-surfaces associated, is called the
+ parent surface. Sub-surfaces can be arbitrarily nested and create
+ a tree of sub-surfaces.
+
+ The root surface in a tree of sub-surfaces is the main
+ surface. The main surface cannot be a sub-surface, because
+ sub-surfaces must always have a parent.
+
+ A main surface with its sub-surfaces forms a (compound) window.
+ For window management purposes, this set of wl_surface objects is
+ to be considered as a single window, and it should also behave as
+ such.
+
+ The aim of sub-surfaces is to offload some of the compositing work
+ within a window from clients to the compositor. A prime example is
+ a video player with decorations and video in separate wl_surface
+ objects. This should allow the compositor to pass YUV video buffer
+ processing to dedicated overlay hardware when possible.
+ </description>
+
+ <request name="destroy" type="destructor">
+ <description summary="unbind from the subcompositor interface">
+ Informs the server that the client will not be using this
+ protocol object anymore. This does not affect any other
+ objects, wl_subsurface objects included.
+ </description>
+ </request>
+
+ <enum name="error">
+ <entry name="bad_surface" value="0"
+ summary="the to-be sub-surface is invalid"/>
+ </enum>
+
+ <request name="get_subsurface">
+ <description summary="give a surface the role sub-surface">
+ Create a sub-surface interface for the given surface, and
+ associate it with the given parent surface. This turns a
+ plain wl_surface into a sub-surface.
+
+ The to-be sub-surface must not already have a dedicated
+ purpose, like any shell surface type, cursor image, drag icon,
+ or sub-surface. Otherwise a protocol error is raised.
+ </description>
+
+ <arg name="id" type="new_id" interface="wl_subsurface"
+ summary="the new subsurface object id"/>
+ <arg name="surface" type="object" interface="wl_surface"
+ summary="the surface to be turned into a sub-surface"/>
+ <arg name="parent" type="object" interface="wl_surface"
+ summary="the parent surface"/>
+ </request>
+ </interface>
+
+ <interface name="wl_subsurface" version="1">
+ <description summary="sub-surface interface to a wl_surface">
+ An additional interface to a wl_surface object, which has been
+ made a sub-surface. A sub-surface has one parent surface. A
+ sub-surface's size and position are not limited to that of the parent.
+ Particularly, a sub-surface is not automatically clipped to its
+ parent's area.
+
+ A sub-surface becomes mapped, when a non-NULL wl_buffer is applied
+ and the parent surface is mapped. The order of which one happens
+ first is irrelevant. A sub-surface is hidden if the parent becomes
+ hidden, or if a NULL wl_buffer is applied. These rules apply
+ recursively through the tree of surfaces.
+
+ The behaviour of wl_surface.commit request on a sub-surface
+ depends on the sub-surface's mode. The possible modes are
+ synchronized and desynchronized, see methods
+ wl_subsurface.set_sync and wl_subsurface.set_desync. Synchronized
+ mode caches the wl_surface state to be applied when the parent's
+ state gets applied, and desynchronized mode applies the pending
+ wl_surface state directly. A sub-surface is initially in the
+ synchronized mode.
+
+ Sub-surfaces have also other kind of state, which is managed by
+ wl_subsurface requests, as opposed to wl_surface requests. This
+ state includes the sub-surface position relative to the parent
+ surface (wl_subsurface.set_position), and the stacking order of
+ the parent and its sub-surfaces (wl_subsurface.place_above and
+ .place_below). This state is applied when the parent surface's
+ wl_surface state is applied, regardless of the sub-surface's mode.
+ As the exception, set_sync and set_desync are effective immediately.
+
+ The main surface can be thought to be always in desynchronized mode,
+ since it does not have a parent in the sub-surfaces sense.
+
+ Even if a sub-surface is in desynchronized mode, it will behave as
+ in synchronized mode, if its parent surface behaves as in
+ synchronized mode. This rule is applied recursively throughout the
+ tree of surfaces. This means, that one can set a sub-surface into
+ synchronized mode, and then assume that all its child and grand-child
+ sub-surfaces are synchronized, too, without explicitly setting them.
+
+ If the wl_surface associated with the wl_subsurface is destroyed, the
+ wl_subsurface object becomes inert. Note, that destroying either object
+ takes effect immediately. If you need to synchronize the removal
+ of a sub-surface to the parent surface update, unmap the sub-surface
+ first by attaching a NULL wl_buffer, update parent, and then destroy
+ the sub-surface.
+
+ If the parent wl_surface object is destroyed, the sub-surface is
+ unmapped.
+ </description>
+
+ <request name="destroy" type="destructor">
+ <description summary="remove sub-surface interface">
+ The sub-surface interface is removed from the wl_surface object
+ that was turned into a sub-surface with
+ wl_subcompositor.get_subsurface request. The wl_surface's association
+ to the parent is deleted, and the wl_surface loses its role as
+ a sub-surface. The wl_surface is unmapped.
+ </description>
+ </request>
+
+ <enum name="error">
+ <entry name="bad_surface" value="0"
+ summary="wl_surface is not a sibling or the parent"/>
+ </enum>
+
+ <request name="set_position">
+ <description summary="reposition the sub-surface">
+ This schedules a sub-surface position change.
+ The sub-surface will be moved so, that its origin (top-left
+ corner pixel) will be at the location x, y of the parent surface
+ coordinate system. The coordinates are not restricted to the parent
+ surface area. Negative values are allowed.
+
+ The next wl_surface.commit on the parent surface will reset
+ the sub-surface's position to the scheduled coordinates.
+
+ The initial position is 0, 0.
+ </description>
+
+ <arg name="x" type="int" summary="coordinate in the parent surface"/>
+ <arg name="y" type="int" summary="coordinate in the parent surface"/>
+ </request>
+
+ <request name="place_above">
+ <description summary="restack the sub-surface">
+ This sub-surface is taken from the stack, and put back just
+ above the reference surface, changing the z-order of the sub-surfaces.
+ The reference surface must be one of the sibling surfaces, or the
+ parent surface. Using any other surface, including this sub-surface,
+ will cause a protocol error.
+
+ The z-order is double-buffered state, and will be applied on the
+ next commit of the parent surface.
+ See wl_surface.commit and wl_subcompositor.get_subsurface.
+
+ A new sub-surface is initially added as the top-most in the stack
+ of its siblings and parent.
+ </description>
+
+ <arg name="sibling" type="object" interface="wl_surface"
+ summary="the reference surface"/>
+ </request>
+
+ <request name="place_below">
+ <description summary="restack the sub-surface">
+ The sub-surface is placed just below of the reference surface.
+ See wl_subsurface.place_above.
+ </description>
+
+ <arg name="sibling" type="object" interface="wl_surface"
+ summary="the reference surface"/>
+ </request>
+
+ <request name="set_sync">
+ <description summary="set sub-surface to synchronized mode">
+ Change the commit behaviour of the sub-surface to synchronized
+ mode, also described as the parent dependant mode.
+
+ In synchronized mode, wl_surface.commit on a sub-surface will
+ accumulate the committed state in a cache, but the state will
+ not be applied and hence will not change the compositor output.
+ The cached state is applied to the sub-surface immediately after
+ the parent surface's state is applied. This ensures atomic
+ updates of the parent and all its synchronized sub-surfaces.
+ Applying the cached state will invalidate the cache, so further
+ parent surface commits do not (re-)apply old state.
+
+ See wl_subsurface for the recursive effect of this mode.
+ </description>
+ </request>
+
+ <request name="set_desync">
+ <description summary="set sub-surface to desynchronized mode">
+ Change the commit behaviour of the sub-surface to desynchronized
+ mode, also described as independent or freely running mode.
+
+ In desynchronized mode, wl_surface.commit on a sub-surface will
+ apply the pending state directly, without caching, as happens
+ normally with a wl_surface. Calling wl_surface.commit on the
+ parent surface has no effect on the sub-surface's wl_surface
+ state. This mode allows a sub-surface to be updated on its own.
+
+ If cached state exists when wl_surface.commit is called in
+ desynchronized mode, the pending state is added to the cached
+ state, and applied as whole. This invalidates the cache.
+
+ Note: even if a sub-surface is set to desynchronized, a parent
+ sub-surface may override it to behave as synchronized. For details,
+ see wl_subsurface.
+
+ If a surface's parent surface behaves as desynchronized, then
+ the cached state is applied on set_desync.
+ </description>
+ </request>
+
+ </interface>
+</protocol>