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/*
* Copyright 2008 The Android Open Source Project
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef SkUnPreMultiply_DEFINED
#define SkUnPreMultiply_DEFINED
#include "SkColor.h"
class SK_API SkUnPreMultiply {
public:
typedef uint32_t Scale;
// index this table with alpha [0..255]
static const Scale* GetScaleTable() {
return gTable;
}
static Scale GetScale(U8CPU alpha) {
SkASSERT(alpha <= 255);
return gTable[alpha];
}
/** Usage:
const Scale* table = SkUnPreMultiply::GetScaleTable();
for (...) {
unsigned a = ...
SkUnPreMultiply::Scale scale = table[a];
red = SkUnPreMultiply::ApplyScale(scale, red);
...
// now red is unpremultiplied
}
*/
static U8CPU ApplyScale(Scale scale, U8CPU component) {
SkASSERT(component <= 255);
return (scale * component + (1 << 23)) >> 24;
}
static SkColor PMColorToColor(SkPMColor c);
static uint32_t UnPreMultiplyPreservingByteOrder(SkPMColor c);
private:
static const uint32_t gTable[256];
};
#endif
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