<?xml version="1.0" encoding="UTF-8"?>
<protocol name="xx_color_management_v4">
  <copyright>
    Copyright 2019 Sebastian Wick
    Copyright 2019 Erwin Burema
    Copyright 2020 AMD
    Copyright 2020-2024 Collabora, Ltd.
    Copyright 2024 Xaver Hugl

    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="color management protocol">
    The aim of the color management extension is to allow clients to know
    the color properties of outputs, and to tell the compositor about the color
    properties of their content on surfaces. Doing this enables a compositor
    to perform automatic color management of content for different outputs
    according to how content is intended to look like.

    The color properties are represented as an image description object which
    is immutable after it has been created. A wl_output always has an
    associated image description that clients can observe. A wl_surface
    always has an associated preferred image description as a hint chosen by
    the compositor that clients can also observe. Clients can set an image
    description on a wl_surface to denote the color characteristics of the
    surface contents.

    An image description includes SDR and HDR colorimetry and encoding, HDR
    metadata, and viewing environment parameters. An image description does
    not include the properties set through color-representation extension.
    It is expected that the color-representation extension is used in
    conjunction with the color management extension when necessary,
    particularly with the YUV family of pixel formats.

    Recommendation ITU-T H.273
    "Coding-independent code points for video signal type identification"
    shall be referred to as simply H.273 here.

    The color-and-hdr repository
    (https://gitlab.freedesktop.org/pq/color-and-hdr) contains
    background information on the protocol design and legacy color management.
    It also contains a glossary, learning resources for digital color, tools,
    samples and more.

    The terminology used in this protocol is based on common color science and
    color encoding terminology where possible. The glossary in the color-and-hdr
    repository shall be the authority on the definition of terms in this
    protocol.
  </description>

  <interface name="xx_color_manager_v4" version="1">
    <description summary="color manager singleton">
      A global interface used for getting color management extensions for
      wl_surface and wl_output objects, and for creating client defined image
      description objects. The extension interfaces allow
      getting the image description of outputs and setting the image
      description of surfaces.
    </description>

    <request name="destroy" type="destructor">
      <description summary="destroy the color manager">
        Destroy the xx_color_manager_v4 object. This does not affect any other
        objects in any way.
      </description>
    </request>

    <enum name="error">
      <entry name="unsupported_feature" value="0"
        summary="request not supported" />
      <entry name="surface_exists" value="1"
        summary="color management surface exists already" />
    </enum>

    <enum name="render_intent">
      <description summary="rendering intents">
        See the ICC.1:2022 specification from the International Color Consortium
        for more details about rendering intents.

        The principles of ICC defined rendering intents apply with all types of
        image descriptions, not only those with ICC file profiles.

        Compositors must support the perceptual rendering intent. Other
        rendering intents are optional.
      </description>

      <entry name="perceptual" value="0"
        summary="perceptual" />
      <entry name="relative" value="1"
        summary="media-relative colorimetric" />
      <entry name="saturation" value="2"
        summary="saturation" />
      <entry name="absolute" value="3"
        summary="ICC-absolute colorimetric" />
      <entry name="relative_bpc" value="4"
        summary="media-relative colorimetric + black point compensation" />
    </enum>

    <enum name="feature">
      <description summary="compositor supported features" />

      <entry name="icc_v2_v4" value="0"
        summary="new_icc_creator request" />
      <entry name="parametric" value="1"
        summary="new_parametric_creator request" />
      <entry name="set_primaries" value="2"
        summary="parametric set_primaries request" />
      <entry name="set_tf_power" value="3"
        summary="parametric set_tf_power request" />
      <entry name="set_luminances" value="4"
        summary="parametric set_luminances request" />
      <entry name="set_mastering_display_primaries" value="5">
        <description summary="parametric set_mastering_display_primaries request">
          The compositor supports set_mastering_display_primaries request with a
          target color volume fully contained inside the primary color volume.
        </description>
      </entry>
      <entry name="extended_target_volume" value="6">
        <description summary="parametric target exceeds primary color volume">
          The compositor additionally supports target color volumes that
          extend outside of the primary color volume.

          This can only be advertised if feature set_mastering_display_primaries
          is supported as well.
        </description>
      </entry>
    </enum>

    <enum name="primaries">
      <description summary="named color primaries">
        Named color primaries used to encode well-known sets of primaries. H.273
        is the authority, when it comes to the exact values of primaries and
        authoritative specifications, where an equivalent code point exists.

        Descriptions do list the specifications for convenience.
      </description>

      <entry name="srgb" value="0">
        <description
          summary="Color primaries for the sRGB color space as defined by the BT.709 standard">
          Color primaries as defined by
          - Rec. ITU-R BT.709-6
          - Rec. ITU-R BT.1361-0 conventional colour gamut system and extended
          colour gamut system (historical)
          - IEC 61966-2-1 sRGB or sYCC
          - IEC 61966-2-4
          - Society of Motion Picture and Television Engineers (SMPTE) RP 177
          (1993) Annex B
          Equivalent to H.273 ColourPrimaries code point 1.
        </description>
      </entry>
      <entry name="pal_m" value="1">
        <description summary="Color primaries for PAL-M as defined by the BT.470 standard">
          Color primaries as defined by
          - Rec. ITU-R BT.470-6 System M (historical)
          - United States National Television System Committee 1953
          Recommendation for transmission standards for color television
          - United States Federal Communications Commission (2003) Title 47 Code
          of Federal Regulations 73.682 (a)(20)
          Equivalent to H.273 ColourPrimaries code point 4.
        </description>
      </entry>
      <entry name="pal" value="2">
        <description summary="Color primaries for PAL as defined by the BT.601 standard">
          Color primaries as defined by
          - Rec. ITU-R BT.470-6 System B, G (historical)
          - Rec. ITU-R BT.601-7 625
          - Rec. ITU-R BT.1358-0 625 (historical)
          - Rec. ITU-R BT.1700-0 625 PAL and 625 SECAM
          Equivalent to H.273 ColourPrimaries code point 5.
        </description>
      </entry>
      <entry name="ntsc" value="3">
        <description summary="Color primaries for NTSC as defined by the BT.601 standard">
          Color primaries as defined by
          - Rec. ITU-R BT.601-7 525
          - Rec. ITU-R BT.1358-1 525 or 625 (historical)
          - Rec. ITU-R BT.1700-0 NTSC
          - SMPTE 170M (2004)
          - SMPTE 240M (1999) (historical)
          Equivalent to H.273 ColourPrimaries code point 6 and 7.
        </description>
      </entry>
      <entry name="generic_film" value="4">
        <description summary="Generic film with colour filters using Illuminant C">
          Color primaries as defined by H.273 for generic film.
          Equivalent to H.273 ColourPrimaries code point 8.
        </description>
      </entry>
      <entry name="bt2020" value="5">
        <description summary="Color primaries as defined by the BT.2020 and BT.2100 standard">
          Color primaries as defined by
          - Rec. ITU-R BT.2020-2
          - Rec. ITU-R BT.2100-0
          Equivalent to H.273 ColourPrimaries code point 9.
        </description>
      </entry>
      <entry name="cie1931_xyz" value="6">
        <description summary="Color primaries of the full CIE 1931 XYZ color space">
          Color primaries as defined as the maximum of the CIE 1931 XYZ color
          space by
          - SMPTE ST 428-1
          - (CIE 1931 XYZ as in ISO 11664-1)
          Equivalent to H.273 ColourPrimaries code point 10.
        </description>
      </entry>
      <entry name="dci_p3" value="7">
        <description
          summary="Color primaries of the DCI P3 color space as defined by the SMPTE RP 431 standard">
          Color primaries as defined by Digital Cinema System and published in
          SMPTE RP 431-2 (2011). Equivalent to H.273 ColourPrimaries code point
          11.
        </description>
      </entry>
      <entry name="display_p3" value="8">
        <description
          summary="Color primaries of Display P3 variant of the DCI-P3 color space as defined by the SMPTE EG 432 standard">
          Color primaries as defined by Digital Cinema System and published in
          SMPTE EG 432-1 (2010).
          Equivalent to H.273 ColourPrimaries code point 12.
        </description>
      </entry>
      <entry name="adobe_rgb" value="9">
        <description
          summary="Color primaries of the Adobe RGB color space as defined by the ISO 12640 standard">
          Color primaries as defined by Adobe as "Adobe RGB" and later published
          by ISO 12640-4 (2011).
        </description>
      </entry>
    </enum>

    <enum name="transfer_function">
      <description summary="named transfer functions">
        Named transfer functions used to encode well-known transfer
        characteristics. H.273 is the authority, when it comes to the exact
        formulas and authoritative specifications, where an equivalent code
        point exists.

        Descriptions do list the specifications for convenience.
      </description>

      <entry name="bt709" value="0">
        <description summary="BT.709 transfer function">
          Transfer characteristics as defined by
          - Rec. ITU-R BT.709-6
          - Rec. ITU-R BT.1361-0 conventional colour gamut system (historical)
          Equivalent to H.273 TransferCharacteristics code point 1, 6, 14, 15.
        </description>
      </entry>
      <entry name="gamma22" value="1">
        <description summary="Assumed display gamma 2.2 transfer function">
          Transfer characteristics as defined by
          - Rec. ITU-R BT.470-6 System M (historical)
          - United States National Television System Committee 1953
          Recommendation for transmission standards for color television
          - United States Federal Communications Commission (2003) Title 47 Code
          of Federal Regulations 73.682 (a) (20)
          - Rec. ITU-R BT.1700-0 625 PAL and 625 SECAM
          Equivalent to H.273 TransferCharacteristics code point 4.
        </description>
      </entry>
      <entry name="gamma28" value="2">
        <description summary="Assumed display gamma 2.8 transfer function">
          Transfer characteristics as defined by
          - Rec. ITU-R BT.470-6 System B, G (historical)
          Equivalent to H.273 TransferCharacteristics code point 5.
        </description>
      </entry>
      <entry name="st240" value="3">
        <description summary="SMPTE ST 240 transfer function">
          Transfer characteristics as defined by
          - SMPTE ST 240 (1999)
          Equivalent to H.273 TransferCharacteristics code point 7.
        </description>
      </entry>
      <entry name="linear" value="4">
        <description summary="linear transfer function">
          Linear transfer characteristics.
          Equivalent to H.273 TransferCharacteristics code point 8.
        </description>
      </entry>
      <entry name="log_100" value="5">
        <description summary="logarithmic 100:1 transfer function">
          Logarithmic transfer characteristic (100:1 range).
          Equivalent to H.273 TransferCharacteristics code point 9.
        </description>
      </entry>
      <entry name="log_316" value="6">
        <description summary="logarithmic (100*Sqrt(10) : 1) transfer function">
          Logarithmic transfer characteristic (100 * Sqrt(10) : 1 range).
          Equivalent to H.273 TransferCharacteristics code point 10.
        </description>
      </entry>
      <entry name="xvycc" value="7">
        <description summary="IEC 61966-2-4 transfer function">
          Transfer characteristics as defined by
          - IEC 61966-2-4
          Equivalent to H.273 TransferCharacteristics code point 11.
        </description>
      </entry>
      <entry name="bt1361" value="8">
        <description summary="BT.1361 extended transfer function">
          Transfer characteristics as defined by
          - Rec. ITU-R BT.1361-0 extended colour gamut system (historical)
          Equivalent to H.273 TransferCharacteristics code point 12.
        </description>
      </entry>
      <entry name="srgb" value="9">
        <description summary="sRGB piece-wise transfer function">
          Transfer characteristics as defined by
          - IEC 61966-2-1 sRGB
          Equivalent to H.273 TransferCharacteristics code point 13 with
          MatrixCoefficients set to 0.
        </description>
      </entry>
      <entry name="ext_srgb" value="10">
        <description summary="Extended sRGB piece-wise transfer function">
          Transfer characteristics as defined by
          - IEC 61966-2-1 sYCC
          Equivalent to H.273 TransferCharacteristics code point 13 with
          MatrixCoefficients set to anything but 0.
        </description>
      </entry>
      <entry name="st2084_pq" value="11">
        <description summary="perceptual quantizer transfer function">
          Transfer characteristics as defined by
          - SMPTE ST 2084 (2014) for 10-, 12-, 14- and 16-bit systems
          - Rec. ITU-R BT.2100-2 perceptual quantization (PQ) system
          Equivalent to H.273 TransferCharacteristics code point 16.

          This TF implies these default luminances
          - primary color volume minimum: 0.005 cd/m²
          - primary color volume maximum: 10000 cd/m²
          - reference white: 203 cd/m²
        </description>
      </entry>
      <entry name="st428" value="12">
        <description summary="SMPTE ST 428 transfer function">
          Transfer characteristics as defined by
          - SMPTE ST 428-1 (2019)
          Equivalent to H.273 TransferCharacteristics code point 17.
        </description>
      </entry>
      <entry name="hlg" value="13">
        <description summary="hybrid log-gamma transfer function">
          Transfer characteristics as defined by
          - ARIB STD-B67 (2015)
          - Rec. ITU-R BT.2100-2 hybrid log-gamma (HLG) system
          Equivalent to H.273 TransferCharacteristics code point 18.

          This TF implies these default luminances
          - primary color volume minimum: 0.005 cd/m²
          - primary color volume maximum: 1000 cd/m²
          - reference white: 203 cd/m²
          Note: HLG is a scene referred signal. All absolute luminance values
          used here for HLG assume a 1000 cd/m² display.
        </description>
      </entry>
    </enum>

    <request name="get_output">
      <description summary="create a color management interface for a wl_output">
        This creates a new xx_color_management_output_v4 object for the
        given wl_output.

        See the xx_color_management_output_v4 interface for more details.
      </description>

      <arg name="id" type="new_id" interface="xx_color_management_output_v4" />
      <arg name="output" type="object" interface="wl_output" />
    </request>

    <request name="get_surface">
      <description summary="create a color management interface for a wl_surface">
        If a xx_color_management_surface_v4 object already exists for the given
        wl_surface, the protocol error surface_exists is raised.

        This creates a new color xx_color_management_surface_v4 object for the
        given wl_surface.

        See the xx_color_management_surface_v4 interface for more details.
      </description>

      <arg name="id" type="new_id" interface="xx_color_management_surface_v4" />
      <arg name="surface" type="object" interface="wl_surface" />
    </request>

    <request name="get_feedback_surface">
      <description summary="create a color management feedback interface">
        This creates a new color xx_color_management_feedback_surface_v4 object
        for the given wl_surface.

        See the xx_color_management_feedback_surface_v4 interface for more
        details.
      </description>

      <arg name="id" type="new_id"
        interface="xx_color_management_feedback_surface_v4" />
      <arg name="surface" type="object" interface="wl_surface" />
    </request>

    <request name="new_icc_creator">
      <description summary="make a new ICC-based image description creator object">
        Makes a new ICC-based image description creator object with all
        properties initially unset. The client can then use the object's
        interface to define all the required properties for an image description
        and finally create a xx_image_description_v4 object.

        This request can be used when the compositor advertises
        xx_color_manager_v4.feature.icc_v2_v4.
        Otherwise this request raises the protocol error unsupported_feature.
      </description>

      <arg name="obj"
        type="new_id" interface="xx_image_description_creator_icc_v4"
        summary="the new creator object" />
    </request>

    <request name="new_parametric_creator">
      <description summary="make a new parametric image description creator object">
        Makes a new parametric image description creator object with all
        properties initially unset. The client can then use the object's
        interface to define all the required properties for an image description
        and finally create a xx_image_description_v4 object.

        This request can be used when the compositor advertises
        xx_color_manager_v4.feature.parametric.
        Otherwise this request raises the protocol error unsupported_feature.
      </description>

      <arg name="obj"
        type="new_id" interface="xx_image_description_creator_params_v4"
        summary="the new creator object" />
    </request>

    <event name="supported_intent">
      <description summary="supported rendering intent">
        When this object is created, it shall immediately send this event once
        for each rendering intent the compositor supports.
      </description>

      <arg name="render_intent" type="uint" enum="render_intent"
        summary="rendering intent" />
    </event>

    <event name="supported_feature">
      <description summary="supported features">
        When this object is created, it shall immediately send this event once
        for each compositor supported feature listed in the enumeration.
      </description>

      <arg name="feature" type="uint" enum="feature"
        summary="supported feature" />
    </event>

    <event name="supported_tf_named">
      <description summary="supported named transfer characteristic">
        When this object is created, it shall immediately send this event once
        for each named transfer function the compositor supports with the
        parametric image description creator.
      </description>

      <arg name="tf" type="uint" enum="transfer_function"
        summary="Named transfer function" />
    </event>

    <event name="supported_primaries_named">
      <description summary="supported named primaries">
        When this object is created, it shall immediately send this event once
        for each named set of primaries the compositor supports with the
        parametric image description creator.
      </description>

      <arg name="primaries" type="uint" enum="primaries"
        summary="Named color primaries" />
    </event>
  </interface>

  <interface name="xx_color_management_output_v4" version="1">
    <description summary="output color properties">
      A xx_color_management_output_v4 describes the color properties of an
      output.

      The xx_color_management_output_v4 is associated with the wl_output global
      underlying the wl_output object. Therefore the client destroying the
      wl_output object has no impact, but the compositor removing the output
      global makes the xx_color_management_output_v4 object inert.
    </description>

    <request name="destroy" type="destructor">
      <description summary="destroy the color management output">
        Destroy the color xx_color_management_output_v4 object. This does not
        affect any remaining protocol objects.
      </description>
    </request>

    <event name="image_description_changed">
      <description summary="image description changed">
        This event is sent whenever the image description of the output changed,
        followed by one wl_output.done event common to output events across all
        extensions.

        If the client wants to use the updated image description, it needs to do
        get_image_description again, because image description objects are
        immutable.
      </description>
    </event>

    <request name="get_image_description">
      <description summary="get the image description of the output">
        This creates a new xx_image_description_v4 object for the current image
        description of the output. There always is exactly one image description
        active for an output so the client should destroy the image description
        created by earlier invocations of this request. This request is usually
        sent as a reaction to the image_description_changed event or when
        creating a xx_color_management_output_v4 object.

        The image description of an output represents the color encoding the
        output expects. There might be performance and power advantages, as well
        as improved color reproduction, if a content update matches the image
        description of the output it is being shown on. If a content update is
        shown on any other output than the one it matches the image description
        of, then the color reproduction on those outputs might be considerably
        worse.

        The created xx_image_description_v4 object preserves the image
        description of the output from the time the object was created.

        The resulting image description object allows get_information request.

        If this protocol object is inert, the resulting image description object
        shall immediately deliver the xx_image_description_v4.failed event with
        the no_output cause.

        If the interface version is inadequate for the output's image
        description, meaning that the client does not support all the events
        needed to deliver the crucial information, the resulting image
        description object shall immediately deliver the
        xx_image_description_v4.failed event with the low_version cause.

        Otherwise the object shall immediately deliver the ready event.
      </description>

      <arg name="image_description"
        type="new_id" interface="xx_image_description_v4" />
    </request>
  </interface>

  <interface name="xx_color_management_surface_v4" version="1">
    <description summary="color management extension to a surface">
      A xx_color_management_surface_v4 allows the client to set the color
      space and HDR properties of a surface.

      If the wl_surface associated with the xx_color_management_surface_v4 is
      destroyed, the xx_color_management_surface_v4 object becomes inert.
    </description>

    <request name="destroy" type="destructor">
      <description summary="destroy the color management interface for a surface">
        Destroy the xx_color_management_surface_v4 object and do the same as
        unset_image_description.
      </description>
    </request>

    <enum name="error">
      <description summary="protocol errors" />
      <entry name="render_intent" value="0"
        summary="unsupported rendering intent" />
      <entry name="image_description" value="1"
        summary="invalid image description" />
    </enum>

    <request name="set_image_description">
      <description summary="set the surface image description">
        Set the image description of the underlying surface. The image
        description and rendering intent are double-buffered state, see
        wl_surface.commit.

        It is the client's responsibility to understand the image description
        it sets on a surface, and to provide content that matches that image
        description. Compositors might convert images to match their own or any
        other image descriptions.

        Image description whose creation gracefully failed (received
        xx_image_description_v4.failed) are forbidden in this request, and in
        such case the protocol error image_description is raised.

        All image descriptions whose creation succeeded (received
        xx_image_description_v4.ready) are allowed and must always be accepted
        by the compositor.

        A rendering intent provides the client's preference on how content
        colors should be mapped to each output. The render_intent value must
        be one advertised by the compositor with
        xx_color_manager_v4.render_intent event, otherwise the protocol error
        render_intent is raised.

        By default, a surface does not have an associated image description
        nor a rendering intent. The handling of color on such surfaces is
        compositor implementation defined. Compositors should handle such
        surfaces as sRGB but may handle them differently if they have specific
        requirements.
      </description>

      <arg name="image_description"
        type="object" interface="xx_image_description_v4" />
      <arg name="render_intent"
        type="uint" enum="xx_color_manager_v4.render_intent"
        summary="rendering intent" />
    </request>

    <request name="unset_image_description">
      <description summary="remove the surface image description">
        This request removes any image description from the surface. See
        set_image_description for how a compositor handles a surface without
        an image description. This is double-buffered state, see
        wl_surface.commit.
      </description>
    </request>
  </interface>

  <interface name="xx_color_management_feedback_surface_v4" version="1">
    <description summary="color management extension to a surface">
      A xx_color_management_feedback_surface_v4 allows the client to get the
      preferred color description of a surface.

      If the wl_surface associated with this object is destroyed, the
      xx_color_management_feedback_surface_v4 object becomes inert.
    </description>

    <request name="destroy" type="destructor">
      <description summary="destroy the color management interface for a surface">
        Destroy the xx_color_management_feedback_surface_v4 object.
      </description>
    </request>

    <enum name="error">
      <description summary="protocol errors" />
      <entry name="inert" value="0"
        summary="forbidden request on inert object" />
    </enum>

    <event name="preferred_changed">
      <description summary="the preferred image description changed">
        The preferred image description is the one which likely has the most
        performance and/or quality benefits for the compositor if used by the
        client for its wl_surface contents. This event is sent whenever the
        compositor changes the wl_surface's preferred image description.

        This event is merely a notification. When the client wants to know
        what the preferred image description is, it shall use the get_preferred
        request.

        The preferred image description is not automatically used for anything.
        It is only a hint, and clients may set any valid image description with
        set_image_description but there might be performance and color accuracy
        improvements by providing the wl_surface contents in the preferred
        image description. Therefore clients that can, should render according
        to the preferred image description
      </description>
    </event>

    <request name="get_preferred">
      <description summary="get the preferred image description">
        If this protocol object is inert, the protocol error inert is raised.

        The preferred image description represents the compositor's preferred
        color encoding for this wl_surface at the current time. There might be
        performance and power advantages, as well as improved color
        reproduction, if the image description of a content update matches the
        preferred image description.

        This creates a new xx_image_description_v4 object for the currently
        preferred image description for the wl_surface. The client should
        stop using and destroy the image descriptions created by earlier
        invocations of this request for the associated wl_surface.
        This request is usually sent as a reaction to the preferred_changed
        event or when creating a xx_color_management_feedback_surface_v4 object
        if the client is capable of adapting to image descriptions.

        The created xx_image_description_v4 object preserves the preferred image
        description of the wl_surface from the time the object was created.

        The resulting image description object allows get_information request.

        If the interface version is inadequate for the preferred image
        description, meaning that the client does not support all the
        events needed to deliver the crucial information, the resulting image
        description object shall immediately deliver the
        xx_image_description_v4.failed event with the low_version cause,
        otherwise the object shall immediately deliver the ready event.
      </description>

      <arg name="image_description"
        type="new_id" interface="xx_image_description_v4" />
    </request>
  </interface>

  <interface name="xx_image_description_creator_icc_v4" version="1">
    <description summary="holder of image description ICC information">
      This type of object is used for collecting all the information required
      to create a xx_image_description_v4 object from an ICC file. A complete
      set of required parameters consists of these properties:
      - ICC file

      Each required property must be set exactly once if the client is to create
      an image description. The set requests verify that a property was not
      already set. The create request verifies that all required properties are
      set. There may be several alternative requests for setting each property,
      and in that case the client must choose one of them.

      Once all properties have been set, the create request must be used to
      create the image description object, destroying the creator in the
      process.
    </description>

    <enum name="error">
      <description summary="protocol errors" />

      <entry name="incomplete_set" value="0"
        summary="incomplete parameter set" />
      <entry name="already_set" value="1"
        summary="property already set" />
      <entry name="bad_fd" value="2"
        summary="fd not seekable and readable" />
      <entry name="bad_size" value="3"
        summary="no or too much data" />
      <entry name="out_of_file" value="4"
        summary="offset + length exceeds file size" />
    </enum>

    <request name="create" type="destructor">
      <description summary="Create the image description object from ICC data">
        Create an image description object based on the ICC information
        previously set on this object. A compositor must parse the ICC data in
        some undefined but finite amount of time.

        The completeness of the parameter set is verified. If the set is not
        complete, the protocol error incomplete_set is raised. For the
        definition of a complete set, see the description of this interface.

        If the particular combination of the information is not supported
        by the compositor, the resulting image description object shall
        immediately deliver the xx_image_description_v4.failed event with the
        'unsupported' cause. If a valid image description was created from the
        information, the xx_image_description_v4.ready event will eventually
        be sent instead.

        This request destroys the xx_image_description_creator_icc_v4 object.

        The resulting image description object does not allow get_information
        request.
      </description>

      <arg name="image_description"
        type="new_id" interface="xx_image_description_v4" />
    </request>

    <request name="set_icc_file">
      <description summary="set the ICC profile file">
        Sets the ICC profile file to be used as the basis of the image
        description.

        The data shall be found through the given fd at the given offset, having
        the given length. The fd must seekable and readable. Violating these
        requirements raises the bad_fd protocol error.

        If reading the data fails due to an error independent of the client, the
        compositor shall send the xx_image_description_v4.failed event on the
        created xx_image_description_v4 with the 'operating_system' cause.

        The maximum size of the ICC profile is 4 MB. If length is greater than
        that or zero, the protocol error bad_size is raised. If offset + length
        exceeds the file size, the protocol error out_of_file is raised.

        A compositor may read the file at any time starting from this request
        and only until whichever happens first:
        - If create request was issued, the xx_image_description_v4 object
        delivers either failed or ready event; or
        - if create request was not issued, this
        xx_image_description_creator_icc_v4 object is destroyed.

        A compositor shall not modify the contents of the file, and the fd may
        be sealed for writes and size changes. The client must ensure to its
        best ability that the data does not change while the compositor is
        reading it.

        The data must represent a valid ICC profile. The ICC profile version
        must be 2 or 4, it must be a 3 channel profile and the class must be
        Display or ColorSpace. Violating these requirements will not result in a
        protocol error but will eventually send the
        xx_image_description_v4.failed event on the created
        xx_image_description_v4 with the 'unsupported' cause.

        See the International Color Consortium specification ICC.1:2022 for more
        details about ICC profiles.

        If ICC file has already been set on this object, the protocol error
        already_set is raised.
      </description>

      <arg name="icc_profile" type="fd"
        summary="ICC profile" />
      <arg name="offset" type="uint"
        summary="byte offset in fd to start of ICC data" />
      <arg name="length" type="uint"
        summary="length of ICC data in bytes" />
    </request>
  </interface>

  <interface name="xx_image_description_creator_params_v4" version="1">
    <description summary="holder of image description parameters">
      This type of object is used for collecting all the parameters required
      to create a xx_image_description_v4 object. A complete set of required
      parameters consists of these properties:
      - transfer characteristic function (tf)
      - chromaticities of primaries and white point (primary color volume)

      The following properties are optional and have a well-defined default
      if not explicitly set:
      - primary color volume luminance range
      - reference white luminance level
      - mastering display primaries and white point (target color volume)
      - mastering luminance range
      - maximum content light level
      - maximum frame-average light level

      Each required property must be set exactly once if the client is to create
      an image description. The set requests verify that a property was not
      already set. The create request verifies that all required properties are
      set. There may be several alternative requests for setting each property,
      and in that case the client must choose one of them.

      Once all properties have been set, the create request must be used to
      create the image description object, destroying the creator in the
      process.
    </description>

    <enum name="error">
      <description summary="protocol errors" />

      <entry name="incomplete_set" value="0"
        summary="incomplete parameter set" />
      <entry name="inconsistent_set" value="1"
        summary="invalid combination of parameters" />
      <entry name="already_set" value="2"
        summary="property already set" />
      <entry name="unsupported_feature" value="3"
        summary="request not supported" />
      <entry name="invalid_tf" value="4"
        summary="invalid transfer characteristic" />
      <entry name="invalid_primaries" value="5"
        summary="invalid primaries or white point" />
      <entry name="invalid_luminance" value="6"
        summary="invalid luminance value or range" />
      <entry name="invalid_mastering" value="7"
        summary="invalid mastering information" />
    </enum>

    <request name="create" type="destructor">
      <description summary="Create the image description object using params">
        Create an image description object based on the parameters previously
        set on this object.

        The completeness of the parameter set is verified. If the set is not
        complete, the protocol error incomplete_set is raised. For the
        definition of a complete set, see the description of this interface.

        Also, the combination of the parameter set is verified. If the set is
        not consistent, the protocol error inconsistent_set is raised.

        If the particular combination of the parameter set is not supported
        by the compositor, the resulting image description object shall
        immediately deliver the xx_image_description_v4.failed event with the
        'unsupported' cause. If a valid image description was created from the
        parameter set, the xx_image_description_v4.ready event will eventually
        be sent instead.

        This request destroys the xx_image_description_creator_params_v4
        object.

        The resulting image description object does not allow get_information
        request.
      </description>

      <arg name="image_description"
        type="new_id" interface="xx_image_description_v4" />
    </request>

    <request name="set_tf_named">
      <description summary="named transfer characteristic">
        Sets the transfer characteristic using explicitly enumerated named
        functions.

        When the resulting image description is attached to an image, the
        content should be encoded and decoded according to the industry standard
        practices for the transfer characteristic.

        Only names advertised with xx_color_manager_v4 event supported_tf_named
        are allowed. Other values shall raise the protocol error invalid_tf.

        If transfer characteristic has already been set on this object, the
        protocol error already_set is raised.
      </description>

      <arg name="tf" type="uint" enum="xx_color_manager_v4.transfer_function"
        summary="named transfer function" />
    </request>

    <request name="set_tf_power">
      <description summary="transfer characteristic as a power curve">
        Sets the color component transfer characteristic to a power curve with
        the given exponent. This curve represents the conversion from electrical
        to optical pixel or color values.

        When the resulting image description is attached to an image, the
        content should be encoded with the inverse of the power curve.

        The curve exponent shall be multiplied by 10000 to get the argument eexp
        value to carry the precision of 4 decimals.

        The curve exponent must be at least 1.0 and at most 10.0. Otherwise the
        protocol error invalid_tf is raised.

        If transfer characteristic has already been set on this object, the
        protocol error already_set is raised.

        This request can be used when the compositor advertises
        xx_color_manager_v4.feature.set_tf_power. Otherwise this request raises
        the protocol error unsupported_feature.
      </description>

      <arg name="eexp" type="uint" summary="the exponent * 10000" />
    </request>

    <request name="set_primaries_named">
      <description summary="named primaries">
        Sets the color primaries and white point using explicitly named sets.
        This describes the primary color volume which is the basis for color
        value encoding.

        Only names advertised with xx_color_manager_v4 event
        supported_primaries_named are allowed. Other values shall raise the
        protocol error invalid_primaries.

        If primaries have already been set on this object, the protocol error
        already_set is raised.
      </description>

      <arg name="primaries" type="uint" enum="xx_color_manager_v4.primaries"
        summary="named primaries" />
    </request>

    <request name="set_primaries">
      <description summary="primaries as chromaticity coordinates">
        Sets the color primaries and white point using CIE 1931 xy chromaticity
        coordinates. This describes the primary color volume which is the basis
        for color value encoding.

        Each coordinate value is multiplied by 10000 to get the argument value
        to carry precision of 4 decimals.

        If primaries have already been set on this object, the protocol error
        already_set is raised.

        This request can be used if the compositor advertises
        xx_color_manager_v4.feature.set_primaries. Otherwise this request raises
        the protocol error unsupported_feature.
      </description>

      <arg name="r_x" type="int" summary="Red x * 10000" />
      <arg name="r_y" type="int" summary="Red y * 10000" />
      <arg name="g_x" type="int" summary="Green x * 10000" />
      <arg name="g_y" type="int" summary="Green y * 10000" />
      <arg name="b_x" type="int" summary="Blue x * 10000" />
      <arg name="b_y" type="int" summary="Blue y * 10000" />
      <arg name="w_x" type="int" summary="White x * 10000" />
      <arg name="w_y" type="int" summary="White y * 10000" />
    </request>

    <request name="set_luminances">
      <description summary="primary color volume luminance range and reference white">
        Sets the primary color volume luminance range and the reference white
        luminance level.

        The default luminances are
        - primary color volume minimum: 0.2 cd/m²
        - primary color volume maximum: 80 cd/m²
        - reference white: 80 cd/m²

        Setting a named transfer characteristic can imply other default
        luminances.

        The default luminances get overwritten when this request is used.

        'min_lum' and 'max_lum' specify the minimum and maximum luminances of
        the primary color volume as reproduced by the targeted display.

        'reference_lum' specifies the luminance of the reference white as
        reproduced by the targeted display, and reflects the targeted viewing
        environment.

        Compositors should make sure that all content is anchored, meaning that
        an input signal level of 'reference_lum' on one image description and
        another input signal level of 'reference_lum' on another image
        description should produce the same output level, even though the
        'reference_lum' on both image representations can be different.

        If 'max_lum' is less than the 'reference_lum', or 'reference_lum' is
        less than or equal to 'min_lum', the protocol error invalid_luminance is
        raised.

        The minimum luminance is multiplied by 10000 to get the argument
        'min_lum' value and carries precision of 4 decimals. The maximum
        luminance and reference white luminance values are unscaled.

        If the primary color volume luminance range and the reference white
        luminance level have already been set on this object, the protocol error
        already_set is raised.

        This request can be used if the compositor advertises
        xx_color_manager_v4.feature.set_luminances. Otherwise this request
        raises the protocol error unsupported_feature.
      </description>

      <arg name="min_lum" type="uint"
        summary="minimum luminance (cd/m²) * 10000" />
      <arg name="max_lum" type="uint"
        summary="maximum luminance (cd/m²)" />
      <arg name="reference_lum" type="uint"
        summary="reference white luminance (cd/m²)" />
    </request>

    <request name="set_mastering_display_primaries">
      <description summary="mastering display primaries as chromaticity coordinates">
        Provides the color primaries and white point of the mastering display
        using CIE 1931 xy chromaticity coordinates. This is compatible with the
        SMPTE ST 2086 definition of HDR static metadata.

        The mastering display primaries define the target color volume.

        If mastering display primaries are not explicitly set, the target color
        volume is assumed to be equal to the primary color volume.

        The target color volume is defined by all tristimulus values between 0.0
        and 1.0 (inclusive) of the color space defined by the given mastering
        display primaries and white point. The colorimetry is identical between
        the container color space and the mastering display color space,
        including that no chromatic adaptation is applied even if the white
        points differ.

        The target color volume can exceed the primary color volume to allow for
        a greater color volume with an existing color space definition (for
        example scRGB). It can be smaller than the primary color volume to
        minimize gamut and tone mapping distances for big color spaces (HDR
        metadata).

        To make use of the entire target color volume a suitable pixel format
        has to be chosen (e.g. floating point to exceed the primary color
        volume, or abusing limited quantization range as with xvYCC).

        Each coordinate value is multiplied by 10000 to get the argument value
        to carry precision of 4 decimals.

        If mastering display primaries have already been set on this object, the
        protocol error already_set is raised.

        This request can be used if the compositor advertises
        xx_color_manager_v4.feature.set_mastering_display_primaries. Otherwise
        this request raises the protocol error unsupported_feature. The
        advertisement implies support only for target color volumes fully
        contained within the primary color volume.

        If a compositor additionally supports target color volume exceeding the
        primary color volume, it must advertise
        xx_color_manager_v4.feature.extended_target_volume. If a client uses
        target color volume exceeding the primary color volume and the
        compositor does not support it, the result is implementation defined.
        Compositors are recommended to detect this case and fail the image
        description gracefully, but it may as well result in color artifacts.
      </description>

      <arg name="r_x" type="int" summary="Red x * 10000" />
      <arg name="r_y" type="int" summary="Red y * 10000" />
      <arg name="g_x" type="int" summary="Green x * 10000" />
      <arg name="g_y" type="int" summary="Green y * 10000" />
      <arg name="b_x" type="int" summary="Blue x * 10000" />
      <arg name="b_y" type="int" summary="Blue y * 10000" />
      <arg name="w_x" type="int" summary="White x * 10000" />
      <arg name="w_y" type="int" summary="White y * 10000" />
    </request>

    <request name="set_mastering_luminance">
      <description summary="display mastering luminance range">
        Sets the luminance range that was used during the content mastering
        process as the minimum and maximum absolute luminance L. This is
        compatible with the SMPTE ST 2086 definition of HDR static metadata.

        The mastering luminance range is undefined by default.

        If max L is less than or equal to min L, the protocol error
        invalid_luminance is raised.

        Min L value is multiplied by 10000 to get the argument min_lum value
        and carry precision of 4 decimals. Max L value is unscaled for max_lum.
      </description>

      <arg name="min_lum" type="uint" summary="min L (cd/m²) * 10000" />
      <arg name="max_lum" type="uint" summary="max L (cd/m²)" />
    </request>

    <request name="set_max_cll">
      <description summary="maximum content light level">
        Sets the maximum content light level (max_cll) as defined by CTA-861-H.

        This can only be set when set_tf_cicp is used to set the transfer
        characteristic to Rec. ITU-R BT.2100-2 perceptual quantization system.
        Otherwise, 'create' request shall raise inconsistent_set protocol
        error.

        max_cll is undefined by default.
      </description>

      <arg name="max_cll" type="uint" summary="Maximum content light level (cd/m²)" />
    </request>

    <request name="set_max_fall">
      <description summary="maximum frame-average light level">
        Sets the maximum frame-average light level (max_fall) as defined by
        CTA-861-H.

        This can only be set when set_tf_cicp is used to set the transfer
        characteristic to Rec. ITU-R BT.2100-2 perceptual quantization system.
        Otherwise, 'create' request shall raise inconsistent_set protocol error.

        max_fall is undefined by default.
      </description>

      <arg name="max_fall" type="uint" summary="Maximum frame-average light level (cd/m²)" />
    </request>
  </interface>

  <interface name="xx_image_description_v4" version="1">
    <description summary="Colorimetric image description">
      An image description carries information about the color encoding used on
      a surface when attached to a wl_surface via
      xx_color_management_surface_v4.set_image_description. A compositor can use
      this information to decode pixel values into colorimetrically meaningful
      quantities.

      Note, that the xx_image_description_v4 object is not ready to be used
      immediately after creation. The object eventually delivers either the
      'ready' or the 'failed' event, specified in all requests creating it. The
      object is deemed "ready" after receiving the 'ready' event.

      An object which is not ready is illegal to use, it can only be destroyed.
      Any other request in this interface shall result in the 'not_ready'
      protocol error. Attempts to use an object which is not ready through other
      interfaces shall raise protocol errors defined there.

      Once created and regardless of how it was created, a
      xx_image_description_v4 object always refers to one fixed image
      description. It cannot change after creation.
    </description>

    <request name="destroy" type="destructor">
      <description summary="destroy the image description">
        Destroy this object. It is safe to destroy an object which is not ready.

        Destroying a xx_image_description_v4 object has no side-effects, not
        even if a xx_color_management_surface_v4.set_image_description has not
        yet been followed by a wl_surface.commit.
      </description>
    </request>

    <enum name="error">
      <description summary="protocol errors" />

      <entry name="not_ready" value="0"
        summary="attempted to use an object which is not ready" />
      <entry name="no_information" value="1"
        summary="get_information not allowed" />
    </enum>

    <enum name="cause">
      <description summary="generic reason for failure" />

      <entry name="low_version" value="0"
        summary="interface version too low" />
      <entry name="unsupported" value="1"
        summary="unsupported image description data" />
      <entry name="operating_system" value="2"
        summary="error independent of the client" />
      <entry name="no_output" value="3"
        summary="the relevant output no longer exists" />
    </enum>

    <event name="failed">
      <description summary="graceful error on creating the image description">
        If creating a xx_image_description_v4 object fails for a reason that is
        not defined as a protocol error, this event is sent.

        The requests that create image description objects define whether and
        when this can occur. Only such creation requests can trigger this event.
        This event cannot be triggered after the image description was
        successfully formed.

        Once this event has been sent, the xx_image_description_v4 object will
        never become ready and it can only be destroyed.
      </description>

      <arg name="cause" type="uint" enum="cause"
        summary="generic reason" />
      <arg name="msg" type="string"
        summary="ad hoc human-readable explanation" />
    </event>

    <event name="ready">
      <description summary="indication that the object is ready to be used">
        Once this event has been sent, the xx_image_description_v4 object is
        deemed "ready". Ready objects can be used to send requests and can be
        used through other interfaces.

        Every ready xx_image_description_v4 protocol object refers to an
        underlying image description record in the compositor. Multiple protocol
        objects may end up referring to the same record. Clients may identify
        these "copies" by comparing their id numbers: if the numbers from two
        protocol objects are identical, the protocol objects refer to the same
        image description record. Two different image description records
        cannot have the same id number simultaneously. The id number does not
        change during the lifetime of the image description record.

        The id number is valid only as long as the protocol object is alive. If
        all protocol objects referring to the same image description record are
        destroyed, the id number may be recycled for a different image
        description record.

        Image description id number is not a protocol object id. Zero is
        reserved as an invalid id number. It shall not be possible for a client
        to refer to an image description by its id number in protocol. The id
        numbers might not be portable between Wayland connections.

        This identity allows clients to de-duplicate image description records
        and avoid get_information request if they already have the image
        description information.
      </description>

      <arg name="identity" type="uint" summary="image description id number" />
    </event>

    <request name="get_information">
      <description summary="get information about the image description">
        Creates a xx_image_description_info_v4 object which delivers the
        information that makes up the image description.

        Not all image description protocol objects allow get_information
        request. Whether it is allowed or not is defined by the request that
        created the object. If get_information is not allowed, the protocol
        error no_information is raised.
      </description>

      <arg name="information"
        type="new_id" interface="xx_image_description_info_v4" />
    </request>
  </interface>

  <interface name="xx_image_description_info_v4" version="1">
    <description summary="Colorimetric image description information">
      Sends all matching events describing an image description object exactly
      once and finally sends the 'done' event.

      Once a xx_image_description_info_v4 object has delivered a 'done' event it
      is automatically destroyed.

      Every xx_image_description_info_v4 created from the same
      xx_image_description_v4 shall always return the exact same data.
    </description>

    <event name="done" type="destructor">
      <description summary="end of information">
        Signals the end of information events and destroys the object.
      </description>
    </event>

    <event name="icc_file">
      <description summary="ICC profile matching the image description">
        The icc argument provides a file descriptor to the client which may be
        memory-mapped to provide the ICC profile matching the image description.
        The fd is read-only, and if mapped then it must be mapped with
        MAP_PRIVATE by the client.

        The ICC profile version and other details are determined by the
        compositor. There is no provision for a client to ask for a specific
        kind of a profile.
      </description>

      <arg name="icc" type="fd" summary="ICC profile file descriptor" />
      <arg name="icc_size" type="uint" summary="ICC profile size, in bytes" />
      <!-- Offset always 0, compositor must not expose unnecessary data. -->
    </event>

    <event name="primaries">
      <description summary="primaries as chromaticity coordinates">
        Delivers the primary color volume primaries and white point using CIE
        1931 xy chromaticity coordinates.

        Each coordinate value is multiplied by 10000 to get the argument value
        to carry precision of 4 decimals.
      </description>

      <arg name="r_x" type="int" summary="Red x * 10000" />
      <arg name="r_y" type="int" summary="Red y * 10000" />
      <arg name="g_x" type="int" summary="Green x * 10000" />
      <arg name="g_y" type="int" summary="Green y * 10000" />
      <arg name="b_x" type="int" summary="Blue x * 10000" />
      <arg name="b_y" type="int" summary="Blue y * 10000" />
      <arg name="w_x" type="int" summary="White x * 10000" />
      <arg name="w_y" type="int" summary="White y * 10000" />
    </event>

    <event name="primaries_named">
      <description summary="named primaries">
        Delivers the primary color volume primaries and white point using an
        explicitly enumerated named set.
      </description>

      <arg name="primaries" type="uint" enum="xx_color_manager_v4.primaries"
        summary="named primaries" />
    </event>

    <event name="tf_power">
      <description summary="transfer characteristic as a power curve">
        The color component transfer characteristic of this image description is
        a pure power curve. This event provides the exponent of the power
        function. This curve represents the conversion from electrical to
        optical pixel or color values.

        The curve exponent has been multiplied by 10000 to get the argument eexp
        value to carry the precision of 4 decimals.
      </description>

      <arg name="eexp" type="uint" summary="the exponent * 10000" />
    </event>

    <event name="tf_named">
      <description summary="named transfer characteristic">
        Delivers the transfer characteristic using an explicitly enumerated
        named function.
      </description>

      <arg name="tf" type="uint" enum="xx_color_manager_v4.transfer_function"
        summary="named transfer function" />
    </event>

    <event name="luminances">
      <description summary="primary color volume luminance range and reference white">
        Delivers the primary color volume luminance range and the reference
        white luminance level.

        The minimum luminance is multiplied by 10000 to get the argument
        'min_lum' value and carries precision of 4 decimals. The maximum
        luminance and reference white luminance values are unscaled.
      </description>

      <arg name="min_lum" type="uint"
        summary="minimum luminance (cd/m²) * 10000" />
      <arg name="max_lum" type="uint"
        summary="maximum luminance (cd/m²)" />
      <arg name="reference_lum" type="uint"
        summary="reference white luminance (cd/m²)" />
    </event>

    <event name="target_primaries">
      <description summary="target primaries as chromaticity coordinates">
        Provides the color primaries and white point of the target color volume
        using CIE 1931 xy chromaticity coordinates. This is compatible with the
        SMPTE ST 2086 definition of HDR static metadata for mastering displays.

        While primary color volume is about how color is encoded, the target
        color volume is the actually displayable color volume. If target color
        volume is equal to the primary color volume, then this event is not
        sent.

        Each coordinate value is multiplied by 10000 to get the argument value
        to carry precision of 4 decimals.
      </description>

      <arg name="r_x" type="int" summary="Red x * 10000" />
      <arg name="r_y" type="int" summary="Red y * 10000" />
      <arg name="g_x" type="int" summary="Green x * 10000" />
      <arg name="g_y" type="int" summary="Green y * 10000" />
      <arg name="b_x" type="int" summary="Blue x * 10000" />
      <arg name="b_y" type="int" summary="Blue y * 10000" />
      <arg name="w_x" type="int" summary="White x * 10000" />
      <arg name="w_y" type="int" summary="White y * 10000" />
    </event>

    <event name="target_luminance">
      <description summary="target luminance range">
        Provides the luminance range that the image description is targeting as
        the minimum and maximum absolute luminance L. This is compatible with
        the SMPTE ST 2086 definition of HDR static metadata.

        This luminance range is only theoretical and may not correspond to the
        luminance of light emitted on an actual display.

        Min L value is multiplied by 10000 to get the argument min_lum value and
        carry precision of 4 decimals. Max L value is unscaled for max_lum.
      </description>

      <arg name="min_lum" type="uint" summary="min L (cd/m²) * 10000" />
      <arg name="max_lum" type="uint" summary="max L (cd/m²)" />
    </event>

    <event name="target_max_cll">
      <description summary="target maximum content light level">
        Provides the targeted max_cll of the image description. max_cll is
        defined by CTA-861-H.

        This luminance is only theoretical and may not correspond to the
        luminance of light emitted on an actual display.
      </description>

      <arg name="max_cll" type="uint"
        summary="Maximum content light-level (cd/m²)" />
    </event>

    <event name="target_max_fall">
      <description summary="target maximum frame-average light level">
        Provides the targeted max_fall of the image description. max_fall is
        defined by CTA-861-H.

        This luminance is only theoretical and may not correspond to the
        luminance of light emitted on an actual display.
      </description>

      <arg name="max_fall" type="uint"
        summary="Maximum frame-average light level (cd/m²)" />
    </event>
  </interface>
</protocol>