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 by exporting DMA-BUFs.

    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 interface version bump.
    Backward incompatible changes are done by bumping the version number in
    the protocol and interface 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>

  <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="capture a frame from an output">
        Capture the next frame of a an entire 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>

  <interface name="zwlr_export_dmabuf_frame_v1" version="1">
    <description summary="a DMA-BUF frame">
      This object represents a single DMA-BUF frame.

      If the capture is successful, the compositor will first send a "frame"
      event, followed by one or several "object". When the frame is available
      for readout, the "ready" event is sent.

      If the capture failed, the "cancel" event is sent. This can happen anytime
      before the "ready" event.

      Once either a "ready" or a "cancel" event is received, the client should
      destroy the frame. Once an "object" event is received, the client is
      responsible for closing the associated file descriptor.

      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"
             summary="clients should copy frame before processing"/>
    </enum>

    <event name="frame">
      <description summary="a frame description">
        Main event supplying the client with information about the frame. If the
        capture didn't fail, this event is always emitted first before any other
        events.

        This event is followed by a number of "object" as specified by the
        "num_objects" argument.
      </description>
      <arg name="width" type="uint"
           summary="frame width in pixels"/>
      <arg name="height" type="uint"
           summary="frame height in pixels"/>
      <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)"/>
    </event>

    <event name="object">
      <description summary="an object description">
        Event which serves to supply the client with the file descriptors
        containing the data for each object.

        After receiving this event, the client must always close the file
        descriptor as soon as they're done with it and even if the frame fails.
      </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"/>
      <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"/>
      <arg name="plane_index" type="uint"
           summary="index of the the plane the data in the object applies to"/>
    </event>

    <event name="ready">
      <description summary="indicates frame is available for reading">
        This event is sent as soon as the frame is presented, indicating it is
        available for reading. This event includes the time at which
        presentation happened at.

        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.

        After receiving this event, the client should destroy this object.
      </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"
             summary="temporary error, source will produce more frames"/>
      <entry name="permanent" value="1"
             summary="fatal error, source will not produce frames"/>
      <entry name="resizing" value="2"
             summary="temporary error, source will produce more frames"/>
    </enum>

    <event name="cancel">
      <description summary="indicates the frame is no longer valid">
        If the capture failed or if the frame is no longer valid after the
        "frame" event has been emitted, this event will be used to inform the
        client to scrap the frame.

        If the failure is temporary, the client may capture again the same
        source. If the failure is permanent, any further attempts to capture the
        same source will fail again.

        After receiving this event, the client should destroy this object.
      </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. This request must be called as soon as its no
        longer used.

        It can be called at any time by the client. The client will still have
        to close any FDs it has been given.
      </description>
    </request>
  </interface>
</protocol>