SDL

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<?xml version="1.0" encoding="UTF-8"?>
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<protocol name="alpha_modifier_v1">
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  <copyright>
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    Copyright © 2024 Xaver Hugl
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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_alpha_modifier_v1" version="1">
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    <description summary="surface alpha modifier manager">
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      This interface allows a client to set a factor for the alpha values on a
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      surface, which can be used to offload such operations to the compositor,
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      which can in turn for example offload them to KMS.
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      Warning! The protocol described in this file is currently in the testing
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      phase. Backward compatible changes may be added together with the
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      corresponding interface version bump. Backward incompatible changes can
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      only be done by creating a new major version of the extension.
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    </description>
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    <request name="destroy" type="destructor">
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      <description summary="destroy the alpha modifier manager object">
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        Destroy the alpha modifier manager. This doesn't destroy objects
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        created with the manager.
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      </description>
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    </request>
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    <enum name="error">
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      <entry name="already_constructed" value="0"
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             summary="wl_surface already has a alpha modifier object"/>
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    </enum>
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    <request name="get_surface">
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      <description summary="create a new toplevel decoration object">
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        Create a new alpha modifier surface object associated with the
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        given wl_surface. If there is already such an object associated with
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        the wl_surface, the already_constructed error will be raised.
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      </description>
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      <arg name="id" type="new_id" interface="wp_alpha_modifier_surface_v1"/>
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      <arg name="surface" type="object" interface="wl_surface"/>
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    </request>
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  </interface>
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  <interface name="wp_alpha_modifier_surface_v1" version="1">
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    <description summary="alpha modifier object for a surface">
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      This interface allows the client to set a factor for the alpha values on
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      a surface, which can be used to offload such operations to the compositor.
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      The default factor is UINT32_MAX.
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      This object has to be destroyed before the associated wl_surface. Once the
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      wl_surface is destroyed, all request on this object will raise the
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      no_surface error.
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    </description>
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    <enum name="error">
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      <entry name="no_surface" value="0" summary="wl_surface was destroyed"/>
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    </enum>
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    <request name="destroy" type="destructor">
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      <description summary="destroy the alpha modifier object">
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        This destroys the object, and is equivalent to set_multiplier with
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        a value of UINT32_MAX, with the same double-buffered semantics as
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        set_multiplier.
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      </description>
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    </request>
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    <request name="set_multiplier">
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      <description summary="specify the alpha multiplier">
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        Sets the alpha multiplier for the surface. The alpha multiplier is
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        double-buffered state, see wl_surface.commit for details.
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        This factor is applied in the compositor's blending space, as an
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        additional step after the processing of per-pixel alpha values for the
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        wl_surface. The exact meaning of the factor is thus undefined, unless
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        the blending space is specified in a different extension.
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        This multiplier is applied even if the buffer attached to the
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        wl_surface doesn't have an alpha channel; in that case an alpha value
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        of one is used instead.
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        Zero means completely transparent, UINT32_MAX means completely opaque.
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      </description>
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      <arg name="factor" type="uint"/>
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    </request>
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  </interface>
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</protocol>
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