BLI_color.hh

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/* SPDX-FileCopyrightText: 2023 Blender Authors
 *
 * SPDX-License-Identifier: GPL-2.0-or-later */
 
#pragma once
 
#include <ostream>
 
#include "BLI_math_color.h"
#include "BLI_struct_equality_utils.hh"
 
namespace blender {
 
enum class eAlpha {
  Straight,
  Premultiplied,
};
std::ostream &operator<<(std::ostream &stream, const eAlpha &space);
 
enum class eSpace {
  Theme,
  SceneLinear,
  SceneLinearByteEncoded,
};
std::ostream &operator<<(std::ostream &stream, const eSpace &space);
 
template<typename ChannelStorageType, eSpace Space, eAlpha Alpha> class ColorRGBA {
 public:
  ChannelStorageType r, g, b, a;
  constexpr ColorRGBA() = default;
 
  constexpr ColorRGBA(const ChannelStorageType rgba[4])
      : r(rgba[0]), g(rgba[1]), b(rgba[2]), a(rgba[3])
  {
  }
 
  constexpr ColorRGBA(const ChannelStorageType r,
                      const ChannelStorageType g,
                      const ChannelStorageType b,
                      const ChannelStorageType a)
      : r(r), g(g), b(b), a(a)
  {
  }
 
  operator ChannelStorageType *()
  {
    return &r;
  }
 
  operator const ChannelStorageType *() const
  {
    return &r;
  }
 
  friend std::ostream &operator<<(std::ostream &stream,
                                  const ColorRGBA<ChannelStorageType, Space, Alpha> &c)
  {
 
    stream << Space << Alpha << "(" << c.r << ", " << c.g << ", " << c.b << ", " << c.a << ")";
    return stream;
  }
 
  BLI_STRUCT_EQUALITY_OPERATORS_4(ColorRGBA, r, g, b, a)
 
  uint64_t hash() const
  {
    uint64_t x1 = *reinterpret_cast<const uint32_t *>(&r);
    uint64_t x2 = *reinterpret_cast<const uint32_t *>(&g);
    uint64_t x3 = *reinterpret_cast<const uint32_t *>(&b);
    uint64_t x4 = *reinterpret_cast<const uint32_t *>(&a);
    return (x1 * 1283591) ^ (x2 * 850177) ^ (x3 * 735391) ^ (x4 * 442319);
  }
};
 
/* Forward declarations of concrete color classes. */
 
template<eAlpha Alpha> class ColorSceneLinear4f;
template<eAlpha Alpha> class ColorSceneLinearByteEncoded4b;
template<typename ChannelStorageType> class ColorTheme4;
 
/* Forward declaration of precision conversion methods. */
 
BLI_INLINE ColorTheme4<float> BLI_color_convert_to_theme4f(const ColorTheme4<uint8_t> &theme4b);
BLI_INLINE ColorTheme4<uint8_t> BLI_color_convert_to_theme4b(const ColorTheme4<float> &theme4f);
 
template<eAlpha Alpha>
class ColorSceneLinear4f final : public ColorRGBA<float, eSpace::SceneLinear, Alpha> {
 public:
  constexpr ColorSceneLinear4f() = default;
 
  constexpr ColorSceneLinear4f(const float *rgba)
      : ColorRGBA<float, eSpace::SceneLinear, Alpha>(rgba)
  {
  }
 
  constexpr ColorSceneLinear4f(float r, float g, float b, float a)
      : ColorRGBA<float, eSpace::SceneLinear, Alpha>(r, g, b, a)
  {
  }
 
  ColorSceneLinearByteEncoded4b<Alpha> encode() const
  {
    ColorSceneLinearByteEncoded4b<Alpha> encoded;
    linearrgb_to_srgb_uchar4(encoded, *this);
    return encoded;
  }
 
  ColorSceneLinear4f<eAlpha::Premultiplied> premultiply_alpha() const
  {
    if constexpr (Alpha == eAlpha::Straight) {
      ColorSceneLinear4f<eAlpha::Premultiplied> premultiplied;
      straight_to_premul_v4_v4(premultiplied, *this);
      return premultiplied;
    }
    else {
      return *this;
    }
  }
 
  ColorSceneLinear4f<eAlpha::Straight> unpremultiply_alpha() const
  {
    if constexpr (Alpha == eAlpha::Premultiplied) {
      ColorSceneLinear4f<eAlpha::Straight> straighten;
      premul_to_straight_v4_v4(straighten, *this);
      return straighten;
    }
    else {
      return *this;
    }
  }
};
 
template<eAlpha Alpha>
class ColorSceneLinearByteEncoded4b final
    : public ColorRGBA<uint8_t, eSpace::SceneLinearByteEncoded, Alpha> {
 public:
  constexpr ColorSceneLinearByteEncoded4b() = default;
 
  constexpr ColorSceneLinearByteEncoded4b(const uint8_t *rgba)
      : ColorRGBA<uint8_t, eSpace::SceneLinearByteEncoded, Alpha>(rgba)
  {
  }
 
  constexpr ColorSceneLinearByteEncoded4b(uint8_t r, uint8_t g, uint8_t b, uint8_t a)
      : ColorRGBA<uint8_t, eSpace::SceneLinearByteEncoded, Alpha>(r, g, b, a)
  {
  }
 
  ColorSceneLinear4f<Alpha> decode() const
  {
    ColorSceneLinear4f<Alpha> decoded;
    srgb_to_linearrgb_uchar4(decoded, *this);
    return decoded;
  }
};
 
template<typename ChannelStorageType>
class ColorTheme4 final : public ColorRGBA<ChannelStorageType, eSpace::Theme, eAlpha::Straight> {
 public:
  constexpr ColorTheme4() = default;
 
  constexpr ColorTheme4(const ChannelStorageType *rgba)
      : ColorRGBA<ChannelStorageType, eSpace::Theme, eAlpha::Straight>(rgba)
  {
  }
 
  constexpr ColorTheme4(ChannelStorageType r,
                        ChannelStorageType g,
                        ChannelStorageType b,
                        ChannelStorageType a)
      : ColorRGBA<ChannelStorageType, eSpace::Theme, eAlpha::Straight>(r, g, b, a)
  {
  }
 
  ColorTheme4<float> to_4f() const
  {
    if constexpr ((std::is_same_v<ChannelStorageType, uint8_t>)) {
      return BLI_color_convert_to_theme4f(*this);
    }
    else {
      return *this;
    }
  }
 
  ColorTheme4<uint8_t> to_4b() const
  {
    if constexpr ((std::is_same_v<ChannelStorageType, float>)) {
      return BLI_color_convert_to_theme4b(*this);
    }
    else {
      return *this;
    }
  }
};
 
using ColorTheme4b = ColorTheme4<uint8_t>;
using ColorTheme4f = ColorTheme4<float>;
 
BLI_INLINE ColorTheme4b BLI_color_convert_to_theme4b(const ColorTheme4f &theme4f)
{
  ColorTheme4b theme4b;
  rgba_float_to_uchar(theme4b, theme4f);
  return theme4b;
}
 
BLI_INLINE ColorTheme4f BLI_color_convert_to_theme4f(const ColorTheme4b &theme4b)
{
  ColorTheme4f theme4f;
  rgba_uchar_to_float(theme4f, theme4b);
  return theme4f;
}
 
BLI_INLINE ColorSceneLinear4f<eAlpha::Straight> BLI_color_convert_to_scene_linear(
    const ColorTheme4f &theme4f)
{
  ColorSceneLinear4f<eAlpha::Straight> scene_linear;
  srgb_to_linearrgb_v4(scene_linear, theme4f);
  return scene_linear;
}
 
BLI_INLINE ColorSceneLinear4f<eAlpha::Straight> BLI_color_convert_to_scene_linear(
    const ColorTheme4b &theme4b)
{
  ColorSceneLinear4f<eAlpha::Straight> scene_linear;
  srgb_to_linearrgb_uchar4(scene_linear, theme4b);
  return scene_linear;
}
 
BLI_INLINE ColorTheme4f
BLI_color_convert_to_theme4f(const ColorSceneLinear4f<eAlpha::Straight> &scene_linear)
{
  ColorTheme4f theme4f;
  linearrgb_to_srgb_v4(theme4f, scene_linear);
  return theme4f;
}
 
BLI_INLINE ColorTheme4b
BLI_color_convert_to_theme4b(const ColorSceneLinear4f<eAlpha::Straight> &scene_linear)
{
  ColorTheme4b theme4b;
  linearrgb_to_srgb_uchar4(theme4b, scene_linear);
  return theme4b;
}
 
/* Internal roles. For convenience to shorten the type names and hide complexity. */
 
using ColorGeometry4f = ColorSceneLinear4f<eAlpha::Premultiplied>;
using ColorGeometry4b = ColorSceneLinearByteEncoded4b<eAlpha::Premultiplied>;
using ColorPaint4f = ColorSceneLinear4f<eAlpha::Straight>;
using ColorPaint4b = ColorSceneLinearByteEncoded4b<eAlpha::Straight>;
 
}  // namespace blender