unstable: Add alpha-compositing protocol

It's based on the Chromium Wayland protocol of the same name ([1])
and Alexandros's modified version ([2])with a few changes
made to the blending_equation enumeration.

Add one more blending_equation "src_alpha / src_alpha"

[1] https://chromium.googlesource.com/chromium/src/+/master/third_party/wayland-protocols/unstable/alpha-compositing/alpha-compositing-unstable-v1.xml
[2] https://lists.freedesktop.org/archives/wayland-devel/2017-August/034741.html

Signed-off-by: Haihua Hu <jared.hu@nxp.com>

Conflicts:
	Makefile.am
diff --git a/Makefile.am b/Makefile.am
index 345ae6a..5be2800 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -23,6 +23,7 @@
 	unstable/xdg-decoration/xdg-decoration-unstable-v1.xml	\
 	unstable/linux-explicit-synchronization/linux-explicit-synchronization-unstable-v1.xml \
 	unstable/primary-selection/primary-selection-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..d874156
--- /dev/null
+++ b/unstable/alpha-compositing/README
@@ -0,0 +1,6 @@
+Alpha compositing protocol

+

+Maintainers:

+David Reveman <reveman at chromium.org>

+Alexandros Frantzis <alexandros.frantzis at collabora.com>

+Jared Hu <Jared Hu at nxp.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..0844b3f
--- /dev/null
+++ b/unstable/alpha-compositing/alpha-compositing-unstable-v1.xml
@@ -0,0 +1,136 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<protocol name="alpha_compositing_unstable_v1">
+
+  <copyright>
+    Copyright 2016 The Chromium Authors.
+    Copyright 2017 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">
+      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>
+
+    <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>
+
+    <enum name="error">
+      <entry name="blending_exists" value="0"
+             summary="the surface already has a blending object associated"/>
+    </enum>
+
+    <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>
+  </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.
+
+      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>
+
+    <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>
+
+    <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>
+
+    <request name="set_blending">
+      <description summary="set the blending equation">
+        Set the blending equation for compositing the wl_surface.
+
+        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.
+
+        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>
\ No newline at end of file