Add deprecated support for wl_scaler

[ChangeLog][Compositor] Add deprecated support for the deprecated wl_scaler.

Some clients are stuck on the unofficial Weston protocol wl_scaler instead of
the standardized and stable wp_viewporter. This implements optional support for
wl_scaler.

This patch has been written to be easily removable in Qt 6, and touches a
minimal amount of other code.

The implementation can be tested using the new manual test compositor:
tests/manual/wlscaler.

Weston 1.11.1 has a demo client named weston-resizor, which can be used to
test. Note that although newer versions of Weston also have weston-resizor,
those versions use wp_viewporter instead of wl_scaler, so you really need
1.11.1 or earlier to test.

Fixes: QTBUG-69635
Change-Id: Id572e28044cd764eaf63b1259a92bc589711c39d
Reviewed-by: Paul Olav Tvete <paul.tvete@qt.io>

1 files changed, 208 insertions, 0 deletions

diff --git a/src/3rdparty/protocol/scaler.xml b/src/3rdparty/protocol/scaler.xml
new file mode 100644
index 000000000..0e482a635
--- /dev/null
+++ b/src/3rdparty/protocol/scaler.xml
@@ -0,0 +1,208 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<protocol name="scaler">
+
+  <copyright>
+    Copyright © 2013-2014 Collabora, Ltd.
+
+    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="wl_scaler" version="2">
+    <description summary="surface cropping and scaling">
+      The global interface exposing surface cropping and scaling
+      capabilities is used to instantiate an interface extension for a
+      wl_surface object. This extended interface will then allow
+      cropping and scaling the surface contents, effectively
+      disconnecting the direct relationship between the buffer and the
+      surface size.
+    </description>
+
+    <request name="destroy" type="destructor">
+      <description summary="unbind from the cropping and scaling interface">
+	Informs the server that the client will not be using this
+	protocol object anymore. This does not affect any other objects,
+	wl_viewport objects included.
+      </description>
+    </request>
+
+    <enum name="error">
+      <entry name="viewport_exists" value="0"
+             summary="the surface already has a viewport object associated"/>
+    </enum>
+
+    <request name="get_viewport">
+      <description summary="extend surface interface for crop and scale">
+	Instantiate an interface extension for the given wl_surface to
+	crop and scale its content. If the given wl_surface already has
+	a wl_viewport object associated, the viewport_exists
+	protocol error is raised.
+      </description>
+
+      <arg name="id" type="new_id" interface="wl_viewport"
+           summary="the new viewport interface id"/>
+      <arg name="surface" type="object" interface="wl_surface"
+           summary="the surface"/>
+    </request>
+  </interface>
+
+  <interface name="wl_viewport" version="2">
+    <description summary="crop and scale interface to a wl_surface">
+      An additional interface to a wl_surface object, which allows the
+      client to specify the cropping and scaling of the surface
+      contents.
+
+      This interface allows to define the source rectangle (src_x,
+      src_y, src_width, src_height) from where to take the wl_buffer
+      contents, and scale that to destination size (dst_width,
+      dst_height). This state is double-buffered, and is applied on the
+      next wl_surface.commit.
+
+      The two parts of crop and scale state are independent: the source
+      rectangle, and the destination size. Initially both are unset, that
+      is, no scaling is applied. The whole of the current wl_buffer is
+      used as the source, and the surface size is as defined in
+      wl_surface.attach.
+
+      If the destination size is set, it causes the surface size to become
+      dst_width, dst_height. The source (rectangle) is scaled to exactly
+      this size. This overrides whatever the attached wl_buffer size is,
+      unless the wl_buffer is NULL. If the wl_buffer is NULL, the surface
+      has no content and therefore no size. Otherwise, the size is always
+      at least 1x1 in surface coordinates.
+
+      If the source rectangle is set, it defines what area of the
+      wl_buffer is taken as the source. If the source rectangle is set and
+      the destination size is not set, the surface size becomes the source
+      rectangle size rounded up to the nearest integer. If the source size
+      is already exactly integers, this results in cropping without scaling.
+
+      The coordinate transformations from buffer pixel coordinates up to
+      the surface-local coordinates happen in the following order:
+        1. buffer_transform (wl_surface.set_buffer_transform)
+        2. buffer_scale (wl_surface.set_buffer_scale)
+        3. crop and scale (wl_viewport.set*)
+      This means, that the source rectangle coordinates of crop and scale
+      are given in the coordinates after the buffer transform and scale,
+      i.e. in the coordinates that would be the surface-local coordinates
+      if the crop and scale was not applied.
+
+      If the source rectangle is partially or completely outside of the
+      wl_buffer, then the surface contents are undefined (not void), and
+      the surface size is still dst_width, dst_height.
+
+      The x, y arguments of wl_surface.attach are applied as normal to
+      the surface. They indicate how many pixels to remove from the
+      surface size from the left and the top. In other words, they are
+      still in the surface-local coordinate system, just like dst_width
+      and dst_height are.
+
+      If the wl_surface associated with the wl_viewport is destroyed,
+      the wl_viewport object becomes inert.
+
+      If the wl_viewport object is destroyed, the crop and scale
+      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 scaling and cropping from the surface">
+	The associated wl_surface's crop and scale state is removed.
+	The change is applied on the next wl_surface.commit.
+      </description>
+    </request>
+
+    <enum name="error">
+      <entry name="bad_value" value="0"
+             summary="negative or zero values in width or height"/>
+    </enum>
+
+    <request name="set">
+      <description summary="set the crop and scale state">
+	Set both source rectangle and destination size of the associated
+	wl_surface. See wl_viewport for the description, and relation to
+	the wl_buffer size.
+
+	The bad_value protocol error is raised if src_width or
+	src_height is negative, or if dst_width or dst_height is not
+	positive.
+
+	The crop and scale state is double-buffered state, and will be
+	applied on the next wl_surface.commit.
+
+	Arguments dst_x and dst_y do not exist here, use the x and y
+	arguments to wl_surface.attach. The x, y, dst_width, and dst_height
+	define the surface-local coordinate system irrespective of the
+	attached wl_buffer size.
+      </description>
+
+      <arg name="src_x" type="fixed" summary="source rectangle x"/>
+      <arg name="src_y" type="fixed" summary="source rectangle y"/>
+      <arg name="src_width" type="fixed" summary="source rectangle width"/>
+      <arg name="src_height" type="fixed" summary="source rectangle height"/>
+      <arg name="dst_width" type="int" summary="surface width"/>
+      <arg name="dst_height" type="int" summary="surface height"/>
+    </request>
+
+    <request name="set_source" since="2">
+      <description summary="set the source rectangle for cropping">
+	Set the source rectangle of the associated wl_surface. See
+	wl_viewport for the description, and relation to the wl_buffer
+	size.
+
+	If width is -1.0 and height is -1.0, the source rectangle is unset
+	instead. Any other pair of values for width and height that
+	contains zero or negative values raises the bad_value protocol
+	error.
+
+	The crop and scale state is double-buffered state, and will be
+	applied on the next wl_surface.commit.
+      </description>
+
+      <arg name="x" type="fixed" summary="source rectangle x"/>
+      <arg name="y" type="fixed" summary="source rectangle y"/>
+      <arg name="width" type="fixed" summary="source rectangle width"/>
+      <arg name="height" type="fixed" summary="source rectangle height"/>
+    </request>
+
+    <request name="set_destination" since="2">
+      <description summary="set the surface size for scaling">
+	Set the destination size of the associated wl_surface. See
+	wl_viewport for the description, and relation to the wl_buffer
+	size.
+
+	If width is -1 and height is -1, the destination size is unset
+	instead. Any other pair of values for width and height that
+	contains zero or negative values raises the bad_value protocol
+	error.
+
+	The crop and scale state is double-buffered state, and will be
+	applied on the next wl_surface.commit.
+
+	Arguments x and y do not exist here, use the x and y arguments to
+	wl_surface.attach. The x, y, width, and height define the
+	surface-local coordinate system irrespective of the attached
+	wl_buffer size.
+      </description>
+
+      <arg name="width" type="int" summary="surface width"/>
+      <arg name="height" type="int" summary="surface height"/>
+    </request>
+  </interface>
+</protocol>