64 lines
1.6 KiB
C++
64 lines
1.6 KiB
C++
/*
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* Copyright (C) 2008 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef SkUnPreMultiply_DEFINED
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#define SkUnPreMultiply_DEFINED
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#include "SkColor.h"
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class SkUnPreMultiply {
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public:
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typedef uint32_t Scale;
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// index this table with alpha [0..255]
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static const Scale* GetScaleTable() {
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return gTable;
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}
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static Scale GetScale(U8CPU alpha) {
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SkASSERT(alpha <= 255);
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return gTable[alpha];
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}
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/** Usage:
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const Scale* table = SkUnPreMultiply::GetScaleTable();
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for (...) {
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unsigned a = ...
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SkUnPreMultiply::Scale scale = table[a];
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red = SkUnPreMultiply::ApplyScale(scale, red);
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...
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// now red is unpremultiplied
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}
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*/
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static U8CPU ApplyScale(Scale scale, U8CPU component) {
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SkASSERT(component <= 255);
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return (scale * component + (1 << 23)) >> 24;
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}
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static SkColor PMColorToColor(SkPMColor c);
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private:
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static const uint32_t gTable[256];
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};
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#endif
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