b06faacaf1
BUG= R=reed@google.com Author: mtklein@google.com Review URL: https://codereview.chromium.org/130303005 git-svn-id: http://skia.googlecode.com/svn/trunk@13103 2bbb7eff-a529-9590-31e7-b0007b416f81
59 lines
1.2 KiB
C++
59 lines
1.2 KiB
C++
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/*
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* Copyright 2008 The Android Open Source Project
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*
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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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 SK_API 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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static uint32_t UnPreMultiplyPreservingByteOrder(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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