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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
#ifndef MOZILLA_GFX_SWIZZLE_HELPERS_H_
#define MOZILLA_GFX_SWIZZLE_HELPERS_H_
#include <bit>
#include "mozilla/gfx/Types.h"
namespace mozilla::gfx {
/**
* Convenience macros for dispatching to various format combinations.
*/
// Hash the formats to a relatively dense value to optimize jump table
// generation. The first 6 formats in SurfaceFormat are the 32-bit BGRA variants
// and are the most common formats dispatched here. Room is reserved in the
// lowish bits for up to these 6 destination formats. If a destination format is
// >= 6, the 6th bit is set to avoid collisions.
#define FORMAT_KEY(aSrcFormat, aDstFormat) \
(int(aSrcFormat) * 6 + int(aDstFormat) + (int(int(aDstFormat) >= 6) << 6))
#define FORMAT_CASE_EXPR(aSrcFormat, aDstFormat, ...) \
case FORMAT_KEY(aSrcFormat, aDstFormat): \
__VA_ARGS__; \
return true;
#define FORMAT_CASE(aSrcFormat, aDstFormat, ...) \
FORMAT_CASE_EXPR(aSrcFormat, aDstFormat, FORMAT_CASE_CALL(__VA_ARGS__))
#define FORMAT_CASE_ROW(aSrcFormat, aDstFormat, ...) \
case FORMAT_KEY(aSrcFormat, aDstFormat): \
return &__VA_ARGS__;
/**
* Constexpr functions for analyzing format attributes in templates.
*/
// Whether the CMYK needs to be inverted first.
static constexpr bool ShouldInvert(SurfaceFormat aFormat) {
return aFormat == SurfaceFormat::InvertedCMYK;
}
// Whether B comes before R in pixel memory layout.
static constexpr MOZ_ALWAYS_INLINE bool IsBGRFormat(SurfaceFormat aFormat) {
return aFormat == SurfaceFormat::B8G8R8A8 ||
(std::endian::native == std::endian::little &&
aFormat == SurfaceFormat::R5G6B5_UINT16) ||
aFormat == SurfaceFormat::B8G8R8X8 || aFormat == SurfaceFormat::B8G8R8;
}
// Whether the order of B and R need to be swapped to map from src to dst.
static constexpr MOZ_ALWAYS_INLINE bool ShouldSwapRB(SurfaceFormat aSrcFormat,
SurfaceFormat aDstFormat) {
return IsBGRFormat(aSrcFormat) != IsBGRFormat(aDstFormat);
}
// The starting byte of the RGB components in pixel memory.
static constexpr MOZ_ALWAYS_INLINE uint32_t
RGBByteIndex(SurfaceFormat aFormat) {
return aFormat == SurfaceFormat::A8R8G8B8 ||
aFormat == SurfaceFormat::X8R8G8B8
? 1
: 0;
}
// The byte of the alpha component, which just comes after RGB.
static constexpr MOZ_ALWAYS_INLINE uint32_t
AlphaByteIndex(SurfaceFormat aFormat) {
return (RGBByteIndex(aFormat) + 3) % 4;
}
// The endian-dependent bit shift to access RGB of a UINT32 pixel.
static constexpr MOZ_ALWAYS_INLINE uint32_t RGBBitShift(SurfaceFormat aFormat) {
if constexpr (std::endian::native == std::endian::little) {
return 8 * RGBByteIndex(aFormat);
} else {
return 8 - 8 * RGBByteIndex(aFormat);
}
}
// The endian-dependent bit shift to access alpha of a UINT32 pixel.
static constexpr MOZ_ALWAYS_INLINE uint32_t
AlphaBitShift(SurfaceFormat aFormat) {
return (RGBBitShift(aFormat) + 24) % 32;
}
// Whether the pixel format should ignore the value of the alpha channel and
// treat it as opaque.
static constexpr MOZ_ALWAYS_INLINE bool IgnoreAlpha(SurfaceFormat aFormat) {
return aFormat == SurfaceFormat::B8G8R8X8 ||
aFormat == SurfaceFormat::R8G8B8X8 ||
aFormat == SurfaceFormat::X8R8G8B8;
}
// Whether to force alpha to opaque to map from src to dst.
static constexpr MOZ_ALWAYS_INLINE bool ShouldForceOpaque(
SurfaceFormat aSrcFormat, SurfaceFormat aDstFormat) {
return IgnoreAlpha(aSrcFormat) != IgnoreAlpha(aDstFormat);
}
} // namespace mozilla::gfx
#endif /* MOZILLA_GFX_SWIZZLE_HELPERS_H_ */