7534747e63
Review URL: https://codereview.appspot.com/6518044/ git-svn-id: http://skia.googlecode.com/svn/trunk@5572 2bbb7eff-a529-9590-31e7-b0007b416f81
72 lines
2.1 KiB
C
72 lines
2.1 KiB
C
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/*
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* Copyright 2010 Google Inc.
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*
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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#ifndef GrColor_DEFINED
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#define GrColor_DEFINED
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#include "GrTypes.h"
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/**
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* GrColor is 4 bytes for R, G, B, A, in a compile-time specific order. The
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* components are stored premultiplied.
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*/
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typedef uint32_t GrColor;
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// shift amount to assign a component to a GrColor int
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// These shift values are chosen for compatibility with GL attrib arrays
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// ES doesn't allow BGRA vertex attrib order so if they were not in this order
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// we'd have to swizzle in shaders. Note the assumption that the cpu is little
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// endian.
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#define GrColor_SHIFT_R 0
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#define GrColor_SHIFT_G 8
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#define GrColor_SHIFT_B 16
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#define GrColor_SHIFT_A 24
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/**
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* Pack 4 components (RGBA) into a GrColor int
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*/
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static inline GrColor GrColorPackRGBA(unsigned r, unsigned g,
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unsigned b, unsigned a) {
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GrAssert((uint8_t)r == r);
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GrAssert((uint8_t)g == g);
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GrAssert((uint8_t)b == b);
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GrAssert((uint8_t)a == a);
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return (r << GrColor_SHIFT_R) |
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(g << GrColor_SHIFT_G) |
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(b << GrColor_SHIFT_B) |
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(a << GrColor_SHIFT_A);
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}
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// extract a component (byte) from a GrColor int
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#define GrColorUnpackR(color) (((color) >> GrColor_SHIFT_R) & 0xFF)
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#define GrColorUnpackG(color) (((color) >> GrColor_SHIFT_G) & 0xFF)
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#define GrColorUnpackB(color) (((color) >> GrColor_SHIFT_B) & 0xFF)
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#define GrColorUnpackA(color) (((color) >> GrColor_SHIFT_A) & 0xFF)
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/**
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* Since premultiplied means that alpha >= color, we construct a color with
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* each component==255 and alpha == 0 to be "illegal"
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*/
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#define GrColor_ILLEGAL (~(0xFF << GrColor_SHIFT_A))
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/** Converts a GrColor to an rgba array of GrGLfloat */
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static inline void GrColorToRGBAFloat(GrColor color, float rgba[4]) {
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static const float ONE_OVER_255 = 1.f / 255.f;
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rgba[0] = GrColorUnpackR(color) * ONE_OVER_255;
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rgba[1] = GrColorUnpackG(color) * ONE_OVER_255;
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rgba[2] = GrColorUnpackB(color) * ONE_OVER_255;
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rgba[3] = GrColorUnpackA(color) * ONE_OVER_255;
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}
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#endif
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