gamescope/protocol/gamescope-xwayland.xml

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

  <copyright>
    Copyright © 2021 Valve Corporation

    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="gamescope-specific xwayland protocol">
    This is a private Gamescope protocol. Regular Wayland clients must not use
    it.
  </description>

  <interface name="gamescope_xwayland" version="2">
    <request name="destroy" type="destructor"></request>

    <request name="override_window_content">
      <description summary="override an X11's window wl_surface">
        Xwayland creates a wl_surface for each X11 window. It sends a
        WL_SURFACE_ID client message to indicate the mapping between the X11
        windows and the wl_surface objects.

        This request overrides this mapping for a given X11 window, allowing an
        X11 client to submit buffers via the Wayland protocol. The override
        only affects buffer submission. Everything else (e.g. input events)
        still uses Xwayland's WL_SURFACE_ID.
      </description>
      <arg name="surface" type="object" interface="wl_surface" summary="Wayland surface"/>
      <arg name="x11_window" type="uint" summary="X11 window ID"/>
    </request>

    <request name="swapchain_feedback" since="2">
      <description summary="provide swapchain feedback">
        Provide swapchain feedback to the compositor.

        This is what the useless tearing protocol should have been.
        Absolutely not enough information in the final protocol to do what we want for SteamOS --
        which is have the Allow Tearing toggle apply to *both* Mailbox + Immediate and NOT fifo,
        essentially acting as an override for tearing on/off for games.
        The upstream protocol is very useless for our usecase here.

        Provides image count ahead of time instead of needing to try and calculate it from
        an initial stall if we are doing low latency.

        Provides colorspace info for us to do HDR for both HDR10 PQ and scRGB.
        The upstream HDR efforts seem to have no interest in supporting scRGB but we *need* that so /shrug
        We can do it here now! Yipee!

        Swapchain feedback solves so many problems! :D
      </description>
      <arg name="surface" type="object" interface="wl_surface" summary="Wayland surface"/>
      <arg name="image_count" type="uint" summary="image count of swapchain"/>
      <arg name="vk_format" type="uint" summary="VkFormat of swapchain"/>
      <arg name="vk_colorspace" type="uint" summary="VkColorSpaceKHR of swapchain"/>
      <arg name="vk_composite_alpha" type="uint" summary="VkCompositeAlphaFlagBitsKHR of swapchain"/>
      <arg name="vk_pre_transform" type="uint" summary="VkSurfaceTransformFlagBitsKHR of swapchain"/>
      <arg name="vk_present_mode" type="uint" summary="VkPresentModeKHR of swapchain"/>
      <arg name="vk_clipped" type="uint" summary="clipped (VkBool32) of swapchain"/>
    </request>
  </interface>
</protocol>