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comparison: gfx/skia/trunk/include/core/SkUnPreMultiply.h
gfx/skia/trunk/include/core/SkUnPreMultiply.h
- branch
- TOR_BUG_9701
- changeset 15
- b8a032363ba2
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| -1:000000000000 | 0:aa7825cd2121 |
|---|---|
| 1 | |
| 2 /* | |
| 3 * Copyright 2008 The Android Open Source Project | |
| 4 * | |
| 5 * Use of this source code is governed by a BSD-style license that can be | |
| 6 * found in the LICENSE file. | |
| 7 */ | |
| 8 | |
| 9 | |
| 10 | |
| 11 | |
| 12 | |
| 13 #ifndef SkUnPreMultiply_DEFINED | |
| 14 #define SkUnPreMultiply_DEFINED | |
| 15 | |
| 16 #include "SkColor.h" | |
| 17 | |
| 18 class SK_API SkUnPreMultiply { | |
| 19 public: | |
| 20 typedef uint32_t Scale; | |
| 21 | |
| 22 // index this table with alpha [0..255] | |
| 23 static const Scale* GetScaleTable() { | |
| 24 return gTable; | |
| 25 } | |
| 26 | |
| 27 static Scale GetScale(U8CPU alpha) { | |
| 28 SkASSERT(alpha <= 255); | |
| 29 return gTable[alpha]; | |
| 30 } | |
| 31 | |
| 32 /** Usage: | |
| 33 | |
| 34 const Scale* table = SkUnPreMultiply::GetScaleTable(); | |
| 35 | |
| 36 for (...) { | |
| 37 unsigned a = ... | |
| 38 SkUnPreMultiply::Scale scale = table[a]; | |
| 39 | |
| 40 red = SkUnPreMultiply::ApplyScale(scale, red); | |
| 41 ... | |
| 42 // now red is unpremultiplied | |
| 43 } | |
| 44 */ | |
| 45 static U8CPU ApplyScale(Scale scale, U8CPU component) { | |
| 46 SkASSERT(component <= 255); | |
| 47 return (scale * component + (1 << 23)) >> 24; | |
| 48 } | |
| 49 | |
| 50 static SkColor PMColorToColor(SkPMColor c); | |
| 51 | |
| 52 static uint32_t UnPreMultiplyPreservingByteOrder(SkPMColor c); | |
| 53 | |
| 54 private: | |
| 55 static const uint32_t gTable[256]; | |
| 56 }; | |
| 57 | |
| 58 #endif |
