include/private/SkHdrMetadata.h

/*
 * Copyright 2025 Google LLC
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#ifndef SkHdrMetadata_DEFINED
#define SkHdrMetadata_DEFINED

#include "include/core/SkColorSpace.h"
#include "include/core/SkRefCnt.h"
#include "include/private/base/SkAPI.h"

#include <optional>


class SkData;
class SkString;

namespace skhdr {

/**
 * Content light level metadata.
 * The semantics of this metadata is defined in:
 *   ANSI/CTA-861-H A DTV Profile for Uncompressed High Speed Digital Interfaces
 *   Annex P Calculation of MaxCLL and MaxFALL
 * Slightly different semantics for this metadata are defined in:
 *   Portable Network Graphics (PNG) Specification (Third Edition)
 *   11.3.2.8 cLLI Content Light Level Information
 *   https://www.w3.org/TR/png-3/#cLLI-chunk
 * This metadata should only be used in ways that work with both semantics.
 */
struct SK_API ContentLightLevelInformation {
    float fMaxCLL = 0.f;
    float fMaxFALL = 0.f;

    /**
     * Decode from the binary encoding listed at:
     *   AV1 Bitstream & Decoding Process Specification Version 1.0.0 Errata 1
     *   https://aomediacodec.github.io/av1-spec/av1-spec.pdf
     *   5.8.3 Metadata high dynamic range content light level syntax
     * This encoding is equivalent to:
     *   ITU-T H.265 (V10) (07/2024)
     *   D.2.35 Content light level information SEI message syntax
     * Return false if parsing fails.
     */
    bool parse(const SkData* data);

    /**
     * Serialize to the encoding used by parse().
     */
    sk_sp<SkData> serialize() const;

    /**
     * Decode from the binary encoding listed at:
     *   Portable Network Graphics (PNG) Specification (Third Edition)
     *   11.3.2.8 cLLI Content Light Level Information
     *   https://www.w3.org/TR/png-3/#cLLI-chunk
     * This encoding is not equivalent to the encoding used by parse().
     * Return false if parsing fails.
     */
    bool parsePngChunk(const SkData* data);

    /**
     * Serialize to the encoding used by parsePngChunk().
     */
    sk_sp<SkData> serializePngChunk() const;

    /**
     * Return a human-readable description.
     */
    SkString toString() const;

    bool operator==(const ContentLightLevelInformation& other) const;
    bool operator!=(const ContentLightLevelInformation& other) const {
        return !(*this == other);
    }
};

/**
 * Mastering display color volume metadata.
 * The semantics of this metadata is defined in:
 * SMPTE ST 2086:2018 Mastering Display Color Volume Metadata Supporting
 * High Luminance and Wide Color Gamut Images
 */
struct SK_API MasteringDisplayColorVolume {
    SkColorSpacePrimaries fDisplayPrimaries = {0.f, 0.f, 0.f, 0.f, 0.f, 0.f, 0.f, 0.f};
    float fMaximumDisplayMasteringLuminance = 0.f;
    float fMinimumDisplayMasteringLuminance = 0.f;

    /**
     * The encoding as defined in:
     *   AV1 Bitstream & Decoding Process Specification Version 1.0.0 Errata 1
     *   https://aomediacodec.github.io/av1-spec/av1-spec.pdf
     *   5.8.4 Metadata high dynamic range mastering display color volume syntax
     * This encoding is equivalent to:
     *   ITU-T H.265 (V10) (07/2024)
     *   D.2.35 Content light level information SEI message syntax
     * This encoding is also equivalent to:
     *   Portable Network Graphics (PNG) Specification (Third Edition)
     *   11.3.2.7 mDCV Mastering Display Color Volume
     *   https://www.w3.org/TR/png-3/#mDCV-chunk
     * Return false if parsing fails.
     */
    bool parse(const SkData* data);

    /**
     * Serialize to the encoding used by parse().
     */
    sk_sp<SkData> serialize() const;

    /**
     * Return a human-readable description.
     */
    SkString toString() const;

    bool operator==(const MasteringDisplayColorVolume& other) const;
    bool operator!=(const MasteringDisplayColorVolume& other) const {
        return !(*this == other);
    }
};

/**
 * Structure containing all HDR metadata that can be attached to an image or video frame.
 */
class SK_API Metadata {
  public:
    /**
     * Return a container with no metadata.
     */
    static Metadata MakeEmpty();

    /**
     * If there does not exists Content Light Level Information metadata, then return false.
     * Otherwise return true and if `clli` is non-nullptr then write the metadata to `clli`.
     */
    bool getContentLightLevelInformation(ContentLightLevelInformation* clli) const;

    /**
     * Set the Content Light Level Information metadata.
     */
    void setContentLightLevelInformation(const ContentLightLevelInformation& clli);

    /**
     * If there does not exists Mastering Display Color Volume metadata, then return false.
     * Otherwise return true and if `mdcv` is non-nullptr then write the metadata to `mdcv`.
     */
    bool getMasteringDisplayColorVolume(MasteringDisplayColorVolume* mdcv) const;

    /**
     * Set the Mastering Display Color Volume metadata.
     */
    void setMasteringDisplayColorVolume(const MasteringDisplayColorVolume& mdcv);

    /**
     * Return a human-readable description.
     */
    SkString toString() const;

    bool operator==(const Metadata& other) const;
    bool operator!=(const Metadata& other) const {
      return !(*this == other);
    }

  private:
    std::optional<ContentLightLevelInformation> fContentLightLevelInformation;
    std::optional<MasteringDisplayColorVolume> fMasteringDisplayColorVolume;
};

}  // namespace skhdr

#endif