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/*
* Copyright (C) 2008 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#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);
private:
static const uint32_t gTable[256];
};
#endif
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