1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/gfx/skia/trunk/include/core/SkUnPreMultiply.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,58 @@
1.4 +
1.5 +/*
1.6 + * Copyright 2008 The Android Open Source Project
1.7 + *
1.8 + * Use of this source code is governed by a BSD-style license that can be
1.9 + * found in the LICENSE file.
1.10 + */
1.11 +
1.12 +
1.13 +
1.14 +
1.15 +
1.16 +#ifndef SkUnPreMultiply_DEFINED
1.17 +#define SkUnPreMultiply_DEFINED
1.18 +
1.19 +#include "SkColor.h"
1.20 +
1.21 +class SK_API SkUnPreMultiply {
1.22 +public:
1.23 + typedef uint32_t Scale;
1.24 +
1.25 + // index this table with alpha [0..255]
1.26 + static const Scale* GetScaleTable() {
1.27 + return gTable;
1.28 + }
1.29 +
1.30 + static Scale GetScale(U8CPU alpha) {
1.31 + SkASSERT(alpha <= 255);
1.32 + return gTable[alpha];
1.33 + }
1.34 +
1.35 + /** Usage:
1.36 +
1.37 + const Scale* table = SkUnPreMultiply::GetScaleTable();
1.38 +
1.39 + for (...) {
1.40 + unsigned a = ...
1.41 + SkUnPreMultiply::Scale scale = table[a];
1.42 +
1.43 + red = SkUnPreMultiply::ApplyScale(scale, red);
1.44 + ...
1.45 + // now red is unpremultiplied
1.46 + }
1.47 + */
1.48 + static U8CPU ApplyScale(Scale scale, U8CPU component) {
1.49 + SkASSERT(component <= 255);
1.50 + return (scale * component + (1 << 23)) >> 24;
1.51 + }
1.52 +
1.53 + static SkColor PMColorToColor(SkPMColor c);
1.54 +
1.55 + static uint32_t UnPreMultiplyPreservingByteOrder(SkPMColor c);
1.56 +
1.57 +private:
1.58 + static const uint32_t gTable[256];
1.59 +};
1.60 +
1.61 +#endif
