mirror of https://github.com/axmolengine/axmol.git
64 lines
1.6 KiB
C
64 lines
1.6 KiB
C
|
/*
|
||
|
|
* 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
|