Hi Alexandros and Scott, Here are a few small comments. Overall this proposal looks good.
> This protocol specifies a set of interfaces used to control the alpha > compositing and blending of surface contents. > > It's based on the Chromium Wayland protocol of the same name ([1]) and > an old proposal of this protocol ([2]). > > Differences from v1 proposal: > - Add additional "fromsource" blending equation used by [3] > - Allow the server to advertise which blending equations it supports > - Added a protocol errors for using an unsupported equation > - Added a protocol error for using an invalid alpha value > - Added clarification about wl_surface.set_opaque_region > - Added clarification about per-pixel alpha values This should probably not be part of the commit message (ie. be after "---"). > A proof-of-concept implementation for Weston can be found at: > https://gitlab.freedesktop.org/ascent/weston/tree/alpha-compositing-v1 > [1] https://chromium.googlesource.com/chromium/src/+/master/third_party/wayland-protocols/unstable/alpha-compositing/alpha-compositing-u> nstable-v1.xml > [2] > https://lists.freedesktop.org/archives/wayland-devel/2017-August/034741.html > [3] > https://lists.freedesktop.org/archives/wayland-devel/2018-September/039437.html Signed-off-by tags are missing here. > --- > Makefile.am | 1 + > unstable/alpha-compositing/README | 5 + > .../alpha-compositing-unstable-v1.xml | 172 ++++++++++++++++++ > 3 files changed, 178 insertions(+) > create mode 100644 unstable/alpha-compositing/README > create mode 100644 > unstable/alpha-compositing/alpha-compositing-unstable-v1.xml > > diff --git a/Makefile.am b/Makefile.am > index 6394e26..ac6c9f8 100644 > --- a/Makefile.am > +++ b/Makefile.am > @@ -21,6 +21,7 @@ unstable_protocols = > \ > unstable/xdg-output/xdg-output-unstable-v1.xml > \ > unstable/input-timestamps/input-timestamps-unstable-v1.xml \ > unstable/xdg-decoration/xdg-decoration-unstable-v1.xml \ > + unstable/alpha-compositing/alpha-compositing-unstable-v1.xml > \ > $(NULL) > > stable_protocols = > \ > diff --git a/unstable/alpha-compositing/README > b/unstable/alpha-compositing/README > new file mode 100644 > index 0000000..5826967 > --- /dev/null > +++ b/unstable/alpha-compositing/README > @@ -0,0 +1,5 @@ > +Alpha compositing protocol > + > +Maintainers: > +David Reveman <reve...@chromium.org> > +Alexandros Frantzis <alexandros.frant...@collabora.com> > diff --git a/unstable/alpha-compositing/alpha-compositing-unstable-v1.xml > b/unstable/alpha-compositing/alpha-compositing-unstable-v1.xml > new file mode 100644 > index 0000000..aae1d6e > --- /dev/null > +++ b/unstable/alpha-compositing/alpha-compositing-unstable-v1.xml > @@ -0,0 +1,172 @@ > +<?xml version="1.0" encoding="UTF-8"?> > +<protocol name="alpha_compositing_unstable_v1"> > + > + <copyright> > + Copyright 2016 The Chromium Authors. > + Copyright 2017-2018 Collabora Ltd > + Copyright 2018 NXP > + > + 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 more advanced compositing and blending"> > + This protocol specifies a set of interfaces used to control the alpha > + compositing and blending of surface contents. > + > + 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_alpha_compositing_v1" version="1"> > + <description summary="alpha_compositing"> Maybe the "_" can be removed here? This value is supposed to be human-readable. > + The global interface exposing compositing and blending capabilities is > + used to instantiate an interface extension for a wl_surface object. > + This extended interface will then allow the client to specify the > + blending equation and alpha value used for compositing the wl_surface. > + </description> > + > + <enum name="error"> > + <entry name="blending_exists" value="0" > + summary="the surface already has a blending object associated"/> > + </enum> > + > + <request name="destroy" type="destructor"> > + <description summary="unbind from the blending interface"> > + Informs the server that the client will not be using this > + protocol object anymore. This does not affect any other objects, > + blending objects included. > + </description> > + </request> > + > + <request name="get_blending"> > + <description summary="extend surface interface for blending"> > + Instantiate an interface extension for the given wl_surface to > + provide surface blending. If the given wl_surface already has > + a blending object associated, the BLENDING_EXISTS protocol error > + is raised. > + </description> > + > + <arg name="id" type="new_id" interface="zwp_blending_v1" > + summary="the new blending interface id"/> > + <arg name="surface" type="object" interface="wl_surface" > + summary="the surface"/> > + </request> > + > + <event name="blending"> Maybe this could be called "blending_equation"? Using only "blending" is confusing because there's already a "get_blending" request that creates "zwp_blending_v1" objects. > + <description summary="supported blending equations"> > + This event advertistes the blending equations that the server advertises > + supports. All the supported blending equations are advertised once > + when the client binds to this interface. A roundtrip after binding > + gurantees that the client has received all supported blending guarantees > + equations. > + > + For the definition of the blending equations, see the > + zwp_blending_v1.blending_equation enum. > + > + The server must always advertise the 'none' blending equation. > + </description> > + <arg name="equation" type="uint" summary="the blending equation"/> enum="zwp_blending_v1.blending_equation" > + </event> > + </interface> > + > + <interface name="zwp_blending_v1" version="1"> > + <description summary="blending interface to a wl_surface"> > + An additional interface to a wl_surface object, which allows the > + client to specify the blending equation used for compositing and > + an alpha value applied to the whole surface. > + > + When the blending object is created its blending equation is > + 'none' and its alpha is 1.0, i.e., it's inactive by default. Clients > + can activate it by setting the blending equation and alpha value. > + > + Use of this interface has no effect on the surface's opaque region > + as set by wl_surface.set_opaque_region. Clients must make sure to set > + their opaque region correctly to prevent repaint artifacts. > + > + If the wl_surface associated with the blending object is destroyed, > + the blending object becomes inert. > + > + If the blending object is destroyed, the blending state is removed > + from the wl_surface. The change will be applied on the next > + wl_surface.commit. > + </description> > + > + <enum name="blending_equation"> > + <description summary="different blending equations for compositing"> > + Blending equations that can be used when compositing a surface. > + </description> > + <entry name="none" value="0" summary="blending object is inactive"/> > + <entry name="opaque" value="1" summary="(one, zero)"/> > + <entry name="premultiplied" value="2" summary="(one, > one_minus_src_alpha)"/> > + <entry name="straight" value="3" summary="(src_alpha, > one_minus_src_alpha)"/> > + <entry name="fromsource" value="4" summary="(src_alpha, src_alpha)"/> > + </enum> > + > + <enum name="error"> > + <entry name="invalid_equation" value="0" > + summary="the blending equation is not supported"/> > + <entry name="invalid_alpha" value="1" > + summary="the requested alpha value is outside the interval [0, > 1]"/> > + </enum> > + > + <request name="destroy" type="destructor"> > + <description summary="remove blending from the surface"> > + The associated wl_surface's blending state is removed. > + The change is applied on the next wl_surface.commit. > + </description> > + </request> > + > + <request name="set_blending"> > + <description summary="set the blending equation"> > + Set the blending equation for compositing the wl_surface. > + > + If the requested format was not advertised by the > + zwp_alpha_compositing_v1.blending event, the INVALID_EQUATION > protocol > + error is raised. > + > + The blending equation state is double-buffered state, > + and will be applied on the next wl_surface.commit. > + </description> > + <arg name="equation" type="uint" summary="the new blending equation"/> > + </request> > + > + <request name="set_alpha"> > + <description summary="set the alpha value"> > + Set the alpha value applied to the whole surface for compositing. > This > + alpha value is applied as an additional step after the processing of > + per-pixel alpha values for the wl_surface. > + > + If the requested alpha is outside the interval [0, 1], the > + INVALID_ALPHA protocol error is raised. > + > + The alpha value state is double-buffered state, > + and will be applied on the next wl_surface.commit. > + </description> > + <arg name="value" type="fixed" summary="the new alpha value"/> > + </request> > + </interface> > + > +</protocol> > -- > 2.19.1 > > _______________________________________________ > wayland-devel mailing list > wayland-devel@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/wayland-devel _______________________________________________ wayland-devel mailing list wayland-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/wayland-devel