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/*
* Copyright 2010 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef GrColor_DEFINED
#define GrColor_DEFINED
#include "GrTypes.h"
/**
* GrColor is 4 bytes for R, G, B, A, in a compile-time specific order. The
* components are stored premultiplied.
*/
typedef uint32_t GrColor;
// shift amount to assign a component to a GrColor int
// These shift values are chosen for compatibility with GL attrib arrays
// ES doesn't allow BGRA vertex attrib order so if they were not in this order
// we'd have to swizzle in shaders. Note the assumption that the cpu is little
// endian.
#define GrColor_SHIFT_R 0
#define GrColor_SHIFT_G 8
#define GrColor_SHIFT_B 16
#define GrColor_SHIFT_A 24
/**
* Pack 4 components (RGBA) into a GrColor int
*/
static inline GrColor GrColorPackRGBA(unsigned r, unsigned g,
unsigned b, unsigned a) {
GrAssert((uint8_t)r == r);
GrAssert((uint8_t)g == g);
GrAssert((uint8_t)b == b);
GrAssert((uint8_t)a == a);
return (r << GrColor_SHIFT_R) |
(g << GrColor_SHIFT_G) |
(b << GrColor_SHIFT_B) |
(a << GrColor_SHIFT_A);
}
// extract a component (byte) from a GrColor int
#define GrColorUnpackR(color) (((color) >> GrColor_SHIFT_R) & 0xFF)
#define GrColorUnpackG(color) (((color) >> GrColor_SHIFT_G) & 0xFF)
#define GrColorUnpackB(color) (((color) >> GrColor_SHIFT_B) & 0xFF)
#define GrColorUnpackA(color) (((color) >> GrColor_SHIFT_A) & 0xFF)
/**
* Since premultiplied means that alpha >= color, we construct a color with
* each component==255 and alpha == 0 to be "illegal"
*/
#define GrColor_ILLEGAL (~(0xFF << GrColor_SHIFT_A))
/** Converts a GrColor to an rgba array of GrGLfloat */
static inline void GrColorToRGBAFloat(GrColor color, float rgba[4]) {
static const float ONE_OVER_255 = 1.f / 255.f;
rgba[0] = GrColorUnpackR(color) * ONE_OVER_255;
rgba[1] = GrColorUnpackG(color) * ONE_OVER_255;
rgba[2] = GrColorUnpackB(color) * ONE_OVER_255;
rgba[3] = GrColorUnpackA(color) * ONE_OVER_255;
}
/**
* Flags used for bitfields of color components. They are defined so that the bit order reflects the
* GrColor shift order.
*/
enum GrColorComponentFlags {
kR_GrColorComponentFlag = 1 << (GrColor_SHIFT_R / 8),
kG_GrColorComponentFlag = 1 << (GrColor_SHIFT_G / 8),
kB_GrColorComponentFlag = 1 << (GrColor_SHIFT_B / 8),
kA_GrColorComponentFlag = 1 << (GrColor_SHIFT_A / 8),
kRGB_GrColorComponentFlags = (kR_GrColorComponentFlag | kG_GrColorComponentFlag |
kB_GrColorComponentFlag),
kRGBA_GrColorComponentFlags = (kR_GrColorComponentFlag | kG_GrColorComponentFlag |
kB_GrColorComponentFlag | kA_GrColorComponentFlag)
};
static inline char GrColorComponentFlagToChar(GrColorComponentFlags component) {
GrAssert(GrIsPow2(component));
switch (component) {
case kR_GrColorComponentFlag:
return 'r';
case kG_GrColorComponentFlag:
return 'g';
case kB_GrColorComponentFlag:
return 'b';
case kA_GrColorComponentFlag:
return 'a';
default:
GrCrash("Invalid color component flag.");
return '\0';
}
}
static inline uint32_t GrPixelConfigComponentMask(GrPixelConfig config) {
GrAssert(config >= 0 && config < kGrPixelConfigCnt);
static const uint32_t kFlags[] = {
0, // kUnknown_GrPixelConfig
kA_GrColorComponentFlag, // kAlpha_8_GrPixelConfig
kRGBA_GrColorComponentFlags, // kIndex_8_GrPixelConfig
kRGB_GrColorComponentFlags, // kRGB_565_GrPixelConfig
kRGBA_GrColorComponentFlags, // kRGBA_4444_GrPixelConfig
kRGBA_GrColorComponentFlags, // kRGBA_8888_GrPixelConfig
kRGBA_GrColorComponentFlags, // kBGRA_8888_GrPixelConfig
};
return kFlags[config];
GR_STATIC_ASSERT(0 == kUnknown_GrPixelConfig);
GR_STATIC_ASSERT(1 == kAlpha_8_GrPixelConfig);
GR_STATIC_ASSERT(2 == kIndex_8_GrPixelConfig);
GR_STATIC_ASSERT(3 == kRGB_565_GrPixelConfig);
GR_STATIC_ASSERT(4 == kRGBA_4444_GrPixelConfig);
GR_STATIC_ASSERT(5 == kRGBA_8888_GrPixelConfig);
GR_STATIC_ASSERT(6 == kBGRA_8888_GrPixelConfig);
GR_STATIC_ASSERT(SK_ARRAY_COUNT(kFlags) == kGrPixelConfigCnt);
}
#endif
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