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// Copyright 2016 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef UI_GFX_COLOR_TRANSFORM_H_
#define UI_GFX_COLOR_TRANSFORM_H_
#include <memory>
#include <optional>
#include <string>
#include "base/feature_list.h"
#include "third_party/skia/include/core/SkData.h"
#include "third_party/skia/include/effects/SkRuntimeEffect.h"
#include "ui/gfx/color_space.h"
#include "ui/gfx/color_space_export.h"
#include "ui/gfx/geometry/point3_f.h"
#include "ui/gfx/hdr_metadata.h"
namespace gfx {
class COLOR_SPACE_EXPORT ColorTransform {
public:
// Parameters that must be specified at creation time. Changing these
// parameters will result in an entirely different SkShader.
struct Options {
// Used in testing to verify that optimizations have no effect.
bool disable_optimizations = false;
// Used to adjust the transfer and range adjust matrices.
uint32_t src_bit_depth = kDefaultBitDepth;
uint32_t dst_bit_depth = kDefaultBitDepth;
// If set to true, then map PQ and HLG inputs such that their maximum
// luminance will be `dst_max_luminance_relative`.
bool tone_map_pq_and_hlg_to_dst = false;
};
// Parameters that may be specified when the transform is applied. Changing
// these parameters will change the uniforms for a single SkShader.
struct COLOR_SPACE_EXPORT RuntimeOptions {
RuntimeOptions();
RuntimeOptions(const RuntimeOptions&) = delete;
RuntimeOptions& operator=(const RuntimeOptions&) = delete;
~RuntimeOptions();
// Offset and multiplier used when sampling textures;
float offset = 0.f;
float multiplier = 1.f;
// Used for tone mapping PQ sources.
std::optional<gfx::HDRMetadata> src_hdr_metadata;
// Used for interpreting color spaces whose definition depends on an SDR
// white point and for tone mapping.
float dst_sdr_max_luminance_nits = ColorSpace::kDefaultSDRWhiteLevel;
// The maximum luminance value for the destination, as a multiple of
// `dst_sdr_max_luminance_nits` (so this is 1 for SDR displays).
float dst_max_luminance_relative = 1.f;
};
// TriStimulus is a color coordinate in any color space.
// Channel order is XYZ, RGB or YUV.
typedef Point3F TriStim;
ColorTransform();
ColorTransform(const ColorTransform&) = delete;
ColorTransform& operator=(const ColorTransform&) = delete;
virtual ~ColorTransform();
virtual gfx::ColorSpace GetSrcColorSpace() const = 0;
virtual gfx::ColorSpace GetDstColorSpace() const = 0;
// Perform transformation of colors, |colors| is both input and output.
virtual void Transform(TriStim* colors, size_t num) const = 0;
virtual void Transform(TriStim* colors,
size_t num,
const RuntimeOptions& options) const = 0;
// Returns true if this transform is the identity.
virtual bool IsIdentity() const = 0;
virtual size_t NumberOfStepsForTesting() const = 0;
// Two special cases:
// 1. If no source color space is specified (i.e., src.IsValid() is false), do
// no transformation.
// 2. If the target color space is not defined (i.e., dst.IsValid() is false),
// just apply the range adjust and inverse transfer matrices. This can be used
// for YUV to RGB color conversion.
static std::unique_ptr<ColorTransform> NewColorTransform(
const ColorSpace& src,
const ColorSpace& dst);
static std::unique_ptr<ColorTransform> NewColorTransform(
const ColorSpace& src,
const ColorSpace& dst,
const Options& options);
private:
// The default bit depth assumed by NewColorTransform().
static constexpr int kDefaultBitDepth = 8;
};
} // namespace gfx
#endif // UI_GFX_COLOR_TRANSFORM_H_
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