wlroots/protocol/wlr-export-dmabuf-unstable-v1.xml

<?xml version="1.0" encoding="UTF-8"?>
<protocol name="wlr_export_dmabuf_unstable_v1">

  <copyright>
    Copyright © 2018 Rostislav Pehlivanov

    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="a protocol for low overhead screen content capturing">
    An interface to capture surfaces in an efficient way.
    Overall usage:

    1.) client registers with zwlr_screencontent_manager_v1
    2.) server sends client info about surfaces via "receive_surface_info"
    3.) client subscribes to capture a surface via the "capture" requests
    4.) server sends client events via the "zwlr_screencontent_frame" interface
    5.) client finishes and informs server via the "frame_destroy" event
    6.) client optionally resubscribes via repeating steps 3.) through 5.)
  </description>

  <interface name="zwlr_export_dmabuf_frame_v1" version="1">
    <description summary="a frame ready for readout">
      This object represents a frame which is ready to have its resources
      fetched and used.

      The receive callback shall be called first, followed by the "object"
      callback once per dmabuf object or the "plane" callback, once per dmabuf
      plane. The "ready" event is called last to indicate that all the data has
      been made available for readout, as well as the time at which presentation
      happened at. The ownership of the frame is passed to the client, who's
      responsible for destroying it via the "destroy" event once finished and
      by calling close() on the file descriptors received.
      All frames are read-only and may not be written into or altered.
    </description>

    <enum name="flags">
      <description summary="frame flags">
        Special flags that should be respected by the client.
      </description>
      <entry name="transient" value="0x1" since="1"
             summary="clients should copy frame before processing"/>
    </enum>

    <event name="frame">
      <description summary="main callback">
        Main callback supplying the client with information about the frame,
        as well as an object to serve as context for destruction. Always called
        first before any other events.

        The "transform" argument describes the orientation needed to be applied
        to correctly orient the buffer. For example, a buffer rotated by 90
        degrees will have a value of "3" here, corresponding to the need to
        apply a 270 degree transpose to correctly present the buffer.
      </description>
      <arg name="width" type="uint"
           summary="frame width, scaling factor included"/>
      <arg name="height" type="uint"
           summary="frame height, scaling factor included"/>
      <arg name="offset_x" type="uint"
           summary="crop offset for the x axis"/>
      <arg name="offset_y" type="uint"
           summary="crop offset for the y axis"/>
      <arg name="buffer_flags" type="uint"
           summary="flags which indicate properties (invert, interlacing),
                    has the same values as zwp_linux_buffer_params_v1:flags"/>
      <arg name="flags" type="uint" enum="flags"
           summary="indicates special frame features"/>
      <arg name="format" type="uint"
           summary="format of the frame (DRM_FORMAT_*)"/>
      <arg name="mod_high" type="uint"
           summary="drm format modifier, high"/>
      <arg name="mod_low" type="uint"
           summary="drm format modifier, low"/>
      <arg name="num_objects" type="uint"
           summary="indicates how many objects (FDs) the frame has (max 4)"/>
      <arg name="num_planes" type="uint"
           summary="indicates how many planes the frame has (max 4)"/>
    </event>
    <event name="object">
      <description summary="object receiving callback">
        Callback which serves to supply the client with the file descriptors
        containing the data for each object.
      </description>
      <arg name="index" type="uint"
           summary="index of the current object"/>
      <arg name="fd" type="fd"
           summary="fd of the current object"/>
      <arg name="size" type="uint"
           summary="size in bytes for the current object"/>
    </event>
    <event name="plane">
      <description summary="plane info receiving callback">
        Callback which supplies the client with plane information for each
        plane.
      </description>
      <arg name="index" type="uint"
           summary="index of the current plane"/>
      <arg name="object_index" type="uint"
           summary="index of the object the plane applies to"/>
      <arg name="offset" type="uint"
           summary="starting point for the data in the object's fd"/>
      <arg name="stride" type="uint"
           summary="line size in bytes"/>
    </event>
    <event name="ready">
      <description summary="indicates frame is available for reading">
        Called as soon as the frame is presented, indicating it is available
        for reading.
        The timestamp is expressed as tv_sec_hi, tv_sec_lo, tv_nsec triples,
        each component being an unsigned 32-bit value. Whole seconds are in
        tv_sec which is a 64-bit value combined from tv_sec_hi and tv_sec_lo,
        and the additional fractional part in tv_nsec as nanoseconds. Hence,
        for valid timestamps tv_nsec must be in [0, 999999999].
        The seconds part may have an arbitrary offset at start.
      </description>
      <arg name="tv_sec_hi" type="uint"
           summary="high 32 bits of the seconds part of the timestamp"/>
      <arg name="tv_sec_lo" type="uint"
           summary="low 32 bits of the seconds part of the timestamp"/>
      <arg name="tv_nsec" type="uint"
           summary="nanoseconds part of the timestamp"/>
    </event>

    <enum name="cancel_reason">
      <description summary="cancel reason">
        Indicates reason for cancelling the frame.
      </description>
      <entry name="temporary" value="0" since="1"
             summary="temporary error, source will produce more frames"/>
      <entry name="pernament" value="1" since="1"
             summary="fatal error, source will not produce frames"/>
      <entry name="resizing" value="2" since="1"
             summary="temporary error, source will produce frames"/>
    </enum>

    <event name="cancel">
      <description summary="indicates the frame is no longer valid">
        If the frame is no longer valid after the "frame" event has been called,
        this callback will be used to inform the client to scrap the frame.
        Source is still valid for as long as the subscription function does not
        return NULL.
        This may get called if for instance the surface is in the process of
        resizing.
      </description>
      <arg name="reason" type="uint" enum="cancel_reason"
           summary="indicates a reason for cancelling this frame capture"/>
    </event>

    <request name="destroy" type="destructor">
      <description summary="delete this object, used or not">
        Unreferences the frame, allowing it to be reused. Must be called as soon
        as its no longer used.
        Can be called at any time by the client after the "frame" event, after
        which the compositor will not call any other events unless the client
        resubscribes to capture more. The client will still have to close any
        FDs it has been given.
      </description>
    </request>
  </interface>

  <interface name="zwlr_export_dmabuf_manager_v1" version="1">
    <description summary="manager to inform clients and begin capturing">
      This object is a manager with which to start capturing from sources.
    </description>

    <request name="capture_output">
      <description summary="subscribe to start capturing">
        Request to start capturing from an entire wl_output.
      </description>
      <arg name="frame" type="new_id"
           interface="zwlr_export_dmabuf_frame_v1"/>
      <arg name="overlay_cursor" type="int"
           summary="include custom client hardware cursor on top of the frame"/>
      <arg name="output" type="object" interface="wl_output"/>
    </request>
    <request name="destroy" type="destructor">
      <description summary="destroy the manager">
        All objects created by the manager will still remain valid, until their
        appropriate destroy request has been called.
      </description>
    </request>
  </interface>
</protocol>