| /* include/graphics/SkPorterDuff.h |
| ** |
| ** Copyright 2006, Google Inc. |
| ** |
| ** 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 SkPorterDuff_DEFINED |
| #define SkPorterDuff_DEFINED |
| |
| #include "SkColor.h" |
| |
| class SkXfermode; |
| |
| class SkPorterDuff { |
| public: |
| /** List of predefined xfermodes. In general, the algebra for the modes |
| uses the following symbols: |
| Sa, Sc - source alpha and color |
| Da, Dc - destination alpha and color (before compositing) |
| [a, c] - Resulting (alpha, color) values |
| For these equations, the colors are in premultiplied state. |
| If no xfermode is specified, kSrcOver is assumed. |
| */ |
| enum Mode { |
| kClear_Mode, //!< [0, 0] |
| kSrc_Mode, //!< [Sa, Sc] |
| kDst_Mode, //!< [Da, Dc] |
| kSrcOver_Mode, //!< [Sa + (1 - Sa)*Da, Rc = Sc + (1 - Sa)*Dc] this is the default mode |
| kDstOver_Mode, //!< [Sa + (1 - Sa)*Da, Rc = Dc + (1 - Da)*Sc] |
| kSrcIn_Mode, //!< [Sa * Da, Sc * Da] |
| kDstIn_Mode, //!< [Sa * Da, Sa * Dc] |
| kSrcOut_Mode, //!< [Sa * (1 - Da), Sc * (1 - Da)] |
| kDstOut_Mode, //!< [Da * (1 - Sa), Dc * (1 - Sa)] |
| kSrcATop_Mode, //!< [Da, Sc * Da + (1 - Sa) * Dc] |
| kDstATop_Mode, //!< [Sa, Sa * Dc + Sc * (1 - Da)] |
| kXor_Mode, //!< [Sa + Da - 2 * Sa * Da, Sc * (1 - Da) + (1 - Sa) * Dc] |
| kDarken_Mode, //!< [Sa + Da - Sa\u00B7Da, Sc\u00B7(1 - Da) + Dc\u00B7(1 - Sa) + min(Sc, Dc)] |
| kLighten_Mode, //!< [Sa + Da - Sa\u00B7Da, Sc\u00B7(1 - Da) + Dc\u00B7(1 - Sa) + max(Sc, Dc)] |
| |
| kModeCount |
| }; |
| /** Return an SkXfermode object for the specified mode. |
| */ |
| static SkXfermode* CreateXfermode(Mode mode); |
| |
| /** Return a function pointer to a routine that applies the specified porter-duff |
| transfer mode. |
| */ |
| static SkXfermodeProc GetXfermodeProc(Mode mode); |
| }; |
| |
| #endif |
| |