| /* |
| * 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 |