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skia2/include/gpu/GrColor.h
brianosman a4535a34d1 GrColor4f is yet another 4f color type, unfortunately. 
- Sk4f would be my choice, but it's not allowed in include/
- SkColor4f and SkPM4f are specified to be unpremultiplied/premultiplied, whereas GrColor (and GrColor4f) are either, depending on context.

This adds 12 bytes to GrPaint. Not sure if we want to pay that price. The precision loss for a single value (vs. in a gradient, etc...) may not justify changing the storage type here. Easy enough to back that part out, while still keeping the 4f intermediate type for the helper math that it adds, and for storage and parameter passing in other locations.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2088303002

Review-Url: https://codereview.chromium.org/2088303002
2016-06-24 12:50:19 -07:00

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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"
#include "SkColor.h"
#include "SkColorPriv.h"
#include "SkUnPreMultiply.h"
/**
* GrColor is 4 bytes for R, G, B, A, in a specific order defined below. Whether the color is
* premultiplied or not depends on the context in which it is being used.
*/
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.
#ifdef SK_CPU_BENDIAN
#define GrColor_SHIFT_R 24
#define GrColor_SHIFT_G 16
#define GrColor_SHIFT_B 8
#define GrColor_SHIFT_A 0
#else
#define GrColor_SHIFT_R 0
#define GrColor_SHIFT_G 8
#define GrColor_SHIFT_B 16
#define GrColor_SHIFT_A 24
#endif
/**
* Pack 4 components (RGBA) into a GrColor int
*/
static inline GrColor GrColorPackRGBA(unsigned r, unsigned g, unsigned b, unsigned a) {
SkASSERT((uint8_t)r == r);
SkASSERT((uint8_t)g == g);
SkASSERT((uint8_t)b == b);
SkASSERT((uint8_t)a == a);
return (r << GrColor_SHIFT_R) |
(g << GrColor_SHIFT_G) |
(b << GrColor_SHIFT_B) |
(a << GrColor_SHIFT_A);
}
/**
* Packs a color with an alpha channel replicated across all four channels.
*/
static inline GrColor GrColorPackA4(unsigned a) {
SkASSERT((uint8_t)a == a);
return (a << GrColor_SHIFT_R) |
(a << GrColor_SHIFT_G) |
(a << 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))
#define GrColor_WHITE 0xFFFFFFFF
#define GrColor_TRANSPARENT_BLACK 0x0
/**
* Assert in debug builds that a GrColor is premultiplied.
*/
static inline void GrColorIsPMAssert(GrColor SkDEBUGCODE(c)) {
#ifdef SK_DEBUG
unsigned a = GrColorUnpackA(c);
unsigned r = GrColorUnpackR(c);
unsigned g = GrColorUnpackG(c);
unsigned b = GrColorUnpackB(c);
SkASSERT(r <= a);
SkASSERT(g <= a);
SkASSERT(b <= a);
#endif
}
/** Inverts each color channel. */
static inline GrColor GrInvertColor(GrColor c) {
U8CPU a = GrColorUnpackA(c);
U8CPU r = GrColorUnpackR(c);
U8CPU g = GrColorUnpackG(c);
U8CPU b = GrColorUnpackB(c);
return GrColorPackRGBA(0xff - r, 0xff - g, 0xff - b, 0xff - a);
}
static inline GrColor GrColorMul(GrColor c0, GrColor c1) {
U8CPU r = SkMulDiv255Round(GrColorUnpackR(c0), GrColorUnpackR(c1));
U8CPU g = SkMulDiv255Round(GrColorUnpackG(c0), GrColorUnpackG(c1));
U8CPU b = SkMulDiv255Round(GrColorUnpackB(c0), GrColorUnpackB(c1));
U8CPU a = SkMulDiv255Round(GrColorUnpackA(c0), GrColorUnpackA(c1));
return GrColorPackRGBA(r, g, b, a);
}
static inline GrColor GrColorSatAdd(GrColor c0, GrColor c1) {
unsigned r = SkTMin<unsigned>(GrColorUnpackR(c0) + GrColorUnpackR(c1), 0xff);
unsigned g = SkTMin<unsigned>(GrColorUnpackG(c0) + GrColorUnpackG(c1), 0xff);
unsigned b = SkTMin<unsigned>(GrColorUnpackB(c0) + GrColorUnpackB(c1), 0xff);
unsigned a = SkTMin<unsigned>(GrColorUnpackA(c0) + GrColorUnpackA(c1), 0xff);
return GrColorPackRGBA(r, g, b, 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;
}
/** Normalizes and coverts an uint8_t to a float. [0, 255] -> [0.0, 1.0] */
static inline float GrNormalizeByteToFloat(uint8_t value) {
static const float ONE_OVER_255 = 1.f / 255.f;
return value * ONE_OVER_255;
}
/** Determines whether the color is opaque or not. */
static inline bool GrColorIsOpaque(GrColor color) {
return (color & (0xFFU << GrColor_SHIFT_A)) == (0xFFU << GrColor_SHIFT_A);
}
static inline GrColor GrPremulColor(GrColor color) {
unsigned r = GrColorUnpackR(color);
unsigned g = GrColorUnpackG(color);
unsigned b = GrColorUnpackB(color);
unsigned a = GrColorUnpackA(color);
return GrColorPackRGBA(SkMulDiv255Round(r, a),
SkMulDiv255Round(g, a),
SkMulDiv255Round(b, a),
a);
}
/** Returns an unpremuled version of the GrColor. */
static inline GrColor GrUnpremulColor(GrColor color) {
GrColorIsPMAssert(color);
unsigned r = GrColorUnpackR(color);
unsigned g = GrColorUnpackG(color);
unsigned b = GrColorUnpackB(color);
unsigned a = GrColorUnpackA(color);
SkPMColor colorPM = SkPackARGB32(a, r, g, b);
SkColor colorUPM = SkUnPreMultiply::PMColorToColor(colorPM);
r = SkColorGetR(colorUPM);
g = SkColorGetG(colorUPM);
b = SkColorGetB(colorUPM);
a = SkColorGetA(colorUPM);
return GrColorPackRGBA(r, g, b, a);
}
/**
* Similarly, GrColor4f is 4 floats for R, G, B, A, in that order. And like GrColor, whether
* the color is premultiplied or not depends on the context.
*/
struct GrColor4f {
float fRGBA[4];
GrColor4f() {}
GrColor4f(float r, float g, float b, float a) {
fRGBA[0] = r;
fRGBA[1] = g;
fRGBA[2] = b;
fRGBA[3] = a;
}
static GrColor4f FromGrColor(GrColor color) {
GrColor4f result;
GrColorToRGBAFloat(color, result.fRGBA);
return result;
}
static GrColor4f FromSkColor4f(const SkColor4f& color) {
return GrColor4f(color.fR, color.fG, color.fB, color.fA);
}
GrColor toGrColor() const {
return GrColorPackRGBA(
SkTPin<unsigned>(static_cast<unsigned>(fRGBA[0] * 255.0f + 0.5f), 0, 255),
SkTPin<unsigned>(static_cast<unsigned>(fRGBA[1] * 255.0f + 0.5f), 0, 255),
SkTPin<unsigned>(static_cast<unsigned>(fRGBA[2] * 255.0f + 0.5f), 0, 255),
SkTPin<unsigned>(static_cast<unsigned>(fRGBA[3] * 255.0f + 0.5f), 0, 255));
}
SkColor4f toSkColor4f() const {
return SkColor4f { fRGBA[0], fRGBA[1], fRGBA[2], fRGBA[3] };
}
GrColor4f opaque() const {
return GrColor4f(fRGBA[0], fRGBA[1], fRGBA[2], 1.0f);
}
GrColor4f premul() const {
float a = fRGBA[3];
return GrColor4f(fRGBA[0] * a, fRGBA[1] * a, fRGBA[2] * a, a);
}
};
/**
* 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),
kNone_GrColorComponentFlags = 0,
kRGB_GrColorComponentFlags = (kR_GrColorComponentFlag | kG_GrColorComponentFlag |
kB_GrColorComponentFlag),
kRGBA_GrColorComponentFlags = (kR_GrColorComponentFlag | kG_GrColorComponentFlag |
kB_GrColorComponentFlag | kA_GrColorComponentFlag)
};
GR_MAKE_BITFIELD_OPS(GrColorComponentFlags)
static inline char GrColorComponentFlagToChar(GrColorComponentFlags component) {
SkASSERT(SkIsPow2(component));
switch (component) {
case kR_GrColorComponentFlag:
return 'r';
case kG_GrColorComponentFlag:
return 'g';
case kB_GrColorComponentFlag:
return 'b';
case kA_GrColorComponentFlag:
return 'a';
default:
SkFAIL("Invalid color component flag.");
return '\0';
}
}
static inline uint32_t GrPixelConfigComponentMask(GrPixelConfig config) {
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
kRGBA_GrColorComponentFlags, // kSRGBA_8888_GrPixelConfig
kRGBA_GrColorComponentFlags, // kSBGRA_8888_GrPixelConfig
kRGB_GrColorComponentFlags, // kETC1_GrPixelConfig
kA_GrColorComponentFlag, // kLATC_GrPixelConfig
kA_GrColorComponentFlag, // kR11_EAC_GrPixelConfig
kRGBA_GrColorComponentFlags, // kASTC_12x12_GrPixelConfig
kRGBA_GrColorComponentFlags, // kRGBA_float_GrPixelConfig
kA_GrColorComponentFlag, // kAlpha_16_GrPixelConfig
kRGBA_GrColorComponentFlags, // kRGBA_half_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(7 == kSRGBA_8888_GrPixelConfig);
GR_STATIC_ASSERT(8 == kSBGRA_8888_GrPixelConfig);
GR_STATIC_ASSERT(9 == kETC1_GrPixelConfig);
GR_STATIC_ASSERT(10 == kLATC_GrPixelConfig);
GR_STATIC_ASSERT(11 == kR11_EAC_GrPixelConfig);
GR_STATIC_ASSERT(12 == kASTC_12x12_GrPixelConfig);
GR_STATIC_ASSERT(13 == kRGBA_float_GrPixelConfig);
GR_STATIC_ASSERT(14 == kAlpha_half_GrPixelConfig);
GR_STATIC_ASSERT(15 == kRGBA_half_GrPixelConfig);
GR_STATIC_ASSERT(SK_ARRAY_COUNT(kFlags) == kGrPixelConfigCnt);
}
#endif
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