wayland-protocols: Add protocol for stylus support

third_party/wayland-protocols/unstable/stylus/stylus-unstable-v1.xml

+<?xml version="1.0" encoding="UTF-8"?>
+<protocol name="stylus_unstable_v1">
+
+  <copyright>
+    Copyright 2016 The Chromium Authors.
+
+    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>
+
+  <interface name="zwp_stylus_v1" version="1">
+    <description summary="extends wl_pointer with events for on-screen stylus">
+      Allows a wl_pointer to represent an on-screen stylus. The client can
+      interpret the on-screen stylus like any other mouse device, and use
+      this protocol to obtain detail information about the type of stylus,
+      as well as the force and tilt of the tool.
+
+      These events are to be fired by the server within the same frame as other
+      wl_pointer events.
+
+      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 uinterface version bump.
+      Backward incompatible changes are done by bumping the version number in
+      the protocol and uinterface 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>
+
+    <request name="get_pointer_stylus">
+      <description summary="get stylus interface for pointer">
+        Create pointer_stylus object. See zwp_pointer_stylus_v1 interface for
+        details.
+      </description>
+      <arg name="id" type="new_id" interface="zwp_pointer_stylus_v1"/>
+      <arg name="pointer" type="object" interface="wl_pointer"/>
+    </request>
+  </interface>
+
+  <interface name="zwp_pointer_stylus_v1" version="1">
+    <description summary="stylus extension for pointer">
+      The zwp_pointer_stylus_v1 interface extends the wl_pointer interface with
+      events to describe details about a stylus acting as a pointer.
+    </description>
+
+    <request name="destroy" type="destructor">
+      <description summary="destroy stylus object"/>
+    </request>
+
+    <enum name="tool_type">
+      <description summary="tool type of device."/>
+      <entry name="mouse" value="0" summary="Mouse or touchpad, not a stylus."/>
+      <entry name="pen" value="1" summary="Pen"/>
+      <entry name="touch" value="2" summary="Touch"/>
+      <entry name="eraser" value="3" summary="Eraser"/>
+    </enum>
+
+    <event name="tool_change">

[reveman, 2016/07/14 19:11:06]

what happens if any of these properties change while the focus it not on a
client owned surface? are these events sent when pointer enters a new surface
just like button events are?

[denniskempin, 2016/07/14 20:01:07]

I updated the doc. We sent the tool type upon enter. 

[reveman, 2016/07/14 20:06:09]

Thanks. Sounds good.

+      <description summary="pointing device tool type changed">
+        Notification that the user is using a new tool type. There can only be
+        one tool in use at a time.
+
+        If this event is not sent, the client has to assume a mouse is in
+        use. The remaining events of this protocol are only being generated
+        after this event has been fired with a tool type other than mouse.
+      </description>
+      <arg name="type" type="uint" enum="type" summary="new device type"/>
+    </event>
+
+    <event name="force">
+      <description summary="force change event">
+        Notification of a change in physical force on the surface of the screen.
+
+        The force is calibrated and normalized to the 0 to 1 range.
+      </description>
+      <arg name="time" type="uint" summary="timestamp with millisecond granularity"/>
+      <arg name="force" type="fixed" summary="new value of force"/>
+    </event>
+
+    <event name="tilt">
+      <description summary="force change event">
+        Notification of a change in tilt of the pointing otol.

[reveman, 2016/07/14 19:11:06]

s/otol/tool/

[denniskempin, 2016/07/14 20:01:07]

Done.

+
+        Measured from surface normal as plane angle in degrees, values lie in
+        [-90,90]. A positive x is to the right and a positive y is towards the
+        user.
+      </description>
+      <arg name="time" type="uint" summary="timestamp with millisecond granularity"/>
+      <arg name="tilt_x" type="fixed" summary="tilt in x direction"/>
+      <arg name="tilt_y" type="fixed" summary="tilt in y direction"/>
+    </event>
+  </interface>
+</protocol>