SDL

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<?xml version="1.0" encoding="UTF-8"?>
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<protocol name="viewporter">
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  <copyright>
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    Copyright © 2013-2016 Collabora, Ltd.
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    Permission is hereby granted, free of charge, to any person obtaining a
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    copy of this software and associated documentation files (the "Software"),
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    to deal in the Software without restriction, including without limitation
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    the rights to use, copy, modify, merge, publish, distribute, sublicense,
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    and/or sell copies of the Software, and to permit persons to whom the
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    Software is furnished to do so, subject to the following conditions:
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    The above copyright notice and this permission notice (including the next
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    paragraph) shall be included in all copies or substantial portions of the
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    Software.
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    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
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    THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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    FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
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    DEALINGS IN THE SOFTWARE.
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  </copyright>
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  <interface name="wp_viewporter" version="1">
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    <description summary="surface cropping and scaling">
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      The global interface exposing surface cropping and scaling
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      capabilities is used to instantiate an interface extension for a
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      wl_surface object. This extended interface will then allow
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      cropping and scaling the surface contents, effectively
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      disconnecting the direct relationship between the buffer and the
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      surface size.
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    </description>
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    <request name="destroy" type="destructor">
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      <description summary="unbind from the cropping and scaling interface">
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	Informs the server that the client will not be using this
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	protocol object anymore. This does not affect any other objects,
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	wp_viewport objects included.
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      </description>
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    </request>
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    <enum name="error">
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      <entry name="viewport_exists" value="0"
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             summary="the surface already has a viewport object associated"/>
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    </enum>
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    <request name="get_viewport">
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      <description summary="extend surface interface for crop and scale">
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	Instantiate an interface extension for the given wl_surface to
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	crop and scale its content. If the given wl_surface already has
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	a wp_viewport object associated, the viewport_exists
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	protocol error is raised.
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      </description>
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      <arg name="id" type="new_id" interface="wp_viewport"
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           summary="the new viewport interface id"/>
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      <arg name="surface" type="object" interface="wl_surface"
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           summary="the surface"/>
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    </request>
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  </interface>
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  <interface name="wp_viewport" version="1">
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    <description summary="crop and scale interface to a wl_surface">
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      An additional interface to a wl_surface object, which allows the
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      client to specify the cropping and scaling of the surface
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      contents.
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      This interface works with two concepts: the source rectangle (src_x,
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      src_y, src_width, src_height), and the destination size (dst_width,
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      dst_height). The contents of the source rectangle are scaled to the
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      destination size, and content outside the source rectangle is ignored.
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      This state is double-buffered, and is applied on the next
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      wl_surface.commit.
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      The two parts of crop and scale state are independent: the source
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      rectangle, and the destination size. Initially both are unset, that
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      is, no scaling is applied. The whole of the current wl_buffer is
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      used as the source, and the surface size is as defined in
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      wl_surface.attach.
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      If the destination size is set, it causes the surface size to become
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      dst_width, dst_height. The source (rectangle) is scaled to exactly
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      this size. This overrides whatever the attached wl_buffer size is,
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      unless the wl_buffer is NULL. If the wl_buffer is NULL, the surface
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      has no content and therefore no size. Otherwise, the size is always
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      at least 1x1 in surface local coordinates.
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      If the source rectangle is set, it defines what area of the wl_buffer is
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      taken as the source. If the source rectangle is set and the destination
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      size is not set, then src_width and src_height must be integers, and the
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      surface size becomes the source rectangle size. This results in cropping
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      without scaling. If src_width or src_height are not integers and
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      destination size is not set, the bad_size protocol error is raised when
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      the surface state is applied.
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      The coordinate transformations from buffer pixel coordinates up to
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      the surface-local coordinates happen in the following order:
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        1. buffer_transform (wl_surface.set_buffer_transform)
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        2. buffer_scale (wl_surface.set_buffer_scale)
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        3. crop and scale (wp_viewport.set*)
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      This means, that the source rectangle coordinates of crop and scale
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      are given in the coordinates after the buffer transform and scale,
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      i.e. in the coordinates that would be the surface-local coordinates
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      if the crop and scale was not applied.
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      If src_x or src_y are negative, the bad_value protocol error is raised.
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      Otherwise, if the source rectangle is partially or completely outside of
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      the non-NULL wl_buffer, then the out_of_buffer protocol error is raised
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      when the surface state is applied. A NULL wl_buffer does not raise the
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      out_of_buffer error.
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      The x, y arguments of wl_surface.attach are applied as normal to
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      the surface. They indicate how many pixels to remove from the
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      surface size from the left and the top. In other words, they are
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      still in the surface-local coordinate system, just like dst_width
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      and dst_height are.
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      If the wl_surface associated with the wp_viewport is destroyed,
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      all wp_viewport requests except 'destroy' raise the protocol error
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      no_surface.
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      If the wp_viewport object is destroyed, the crop and scale
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      state is removed from the wl_surface. The change will be applied
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      on the next wl_surface.commit.
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    </description>
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    <request name="destroy" type="destructor">
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      <description summary="remove scaling and cropping from the surface">
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	The associated wl_surface's crop and scale state is removed.
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	The change is applied on the next wl_surface.commit.
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      </description>
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    </request>
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    <enum name="error">
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      <entry name="bad_value" value="0"
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	     summary="negative or zero values in width or height"/>
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      <entry name="bad_size" value="1"
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	     summary="destination size is not integer"/>
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      <entry name="out_of_buffer" value="2"
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	     summary="source rectangle extends outside of the content area"/>
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      <entry name="no_surface" value="3"
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	     summary="the wl_surface was destroyed"/>
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    </enum>
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    <request name="set_source">
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      <description summary="set the source rectangle for cropping">
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	Set the source rectangle of the associated wl_surface. See
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	wp_viewport for the description, and relation to the wl_buffer
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	size.
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	If all of x, y, width and height are -1.0, the source rectangle is
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	unset instead. Any other set of values where width or height are zero
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	or negative, or x or y are negative, raise the bad_value protocol
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	error.
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	The crop and scale state is double-buffered state, and will be
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	applied on the next wl_surface.commit.
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      </description>
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      <arg name="x" type="fixed" summary="source rectangle x"/>
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      <arg name="y" type="fixed" summary="source rectangle y"/>
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      <arg name="width" type="fixed" summary="source rectangle width"/>
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      <arg name="height" type="fixed" summary="source rectangle height"/>
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    </request>
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    <request name="set_destination">
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      <description summary="set the surface size for scaling">
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	Set the destination size of the associated wl_surface. See
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	wp_viewport for the description, and relation to the wl_buffer
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	size.
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	If width is -1 and height is -1, the destination size is unset
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	instead. Any other pair of values for width and height that
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	contains zero or negative values raises the bad_value protocol
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	error.
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	The crop and scale state is double-buffered state, and will be
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	applied on the next wl_surface.commit.
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      </description>
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      <arg name="width" type="int" summary="surface width"/>
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      <arg name="height" type="int" summary="surface height"/>
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    </request>
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  </interface>
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</protocol>
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