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      1 /*
      2  * Copyright (C) 2006 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #ifndef SkPorterDuff_DEFINED
     18 #define SkPorterDuff_DEFINED
     19 
     20 #include "SkColor.h"
     21 #include "SkXfermode.h"
     22 
     23 class SkXfermode;
     24 
     25 /** DEPRECATED - use SkXfermode::Mode instead
     26  */
     27 class SkPorterDuff {
     28 public:
     29     /** List of predefined xfermodes. In general, the algebra for the modes
     30         uses the following symbols:
     31         Sa, Sc  - source alpha and color
     32         Da, Dc - destination alpha and color (before compositing)
     33         [a, c] - Resulting (alpha, color) values
     34         For these equations, the colors are in premultiplied state.
     35         If no xfermode is specified, kSrcOver is assumed.
     36     */
     37     enum Mode {
     38         kClear_Mode,    //!< [0, 0]
     39         kSrc_Mode,      //!< [Sa, Sc]
     40         kDst_Mode,      //!< [Da, Dc]
     41         kSrcOver_Mode,  //!< [Sa + Da - Sa*Da, Rc = Sc + (1 - Sa)*Dc]
     42         kDstOver_Mode,  //!< [Sa + Da - Sa*Da, Rc = Dc + (1 - Da)*Sc]
     43         kSrcIn_Mode,    //!< [Sa * Da, Sc * Da]
     44         kDstIn_Mode,    //!< [Sa * Da, Sa * Dc]
     45         kSrcOut_Mode,   //!< [Sa * (1 - Da), Sc * (1 - Da)]
     46         kDstOut_Mode,   //!< [Da * (1 - Sa), Dc * (1 - Sa)]
     47         kSrcATop_Mode,  //!< [Da, Sc * Da + (1 - Sa) * Dc]
     48         kDstATop_Mode,  //!< [Sa, Sa * Dc + Sc * (1 - Da)]
     49         kXor_Mode,      //!< [Sa + Da - 2 * Sa * Da, Sc * (1 - Da) + (1 - Sa) * Dc]
     50         kDarken_Mode,   //!< [Sa + Da - Sa*Da, Sc*(1 - Da) + Dc*(1 - Sa) + min(Sc, Dc)]
     51         kLighten_Mode,  //!< [Sa + Da - Sa*Da, Sc*(1 - Da) + Dc*(1 - Sa) + max(Sc, Dc)]
     52         kMultiply_Mode, //!< [Sa * Da, Sc * Dc]
     53         kScreen_Mode,   //!< [Sa + Da - Sa * Da, Sc + Dc - Sc * Dc]
     54         kAdd_Mode,      //!< Saturate(S + D)
     55 #ifdef ANDROID
     56         kOverlay_Mode,
     57 #endif
     58 
     59         kModeCount
     60     };
     61 
     62     /** Return an SkXfermode object for the specified mode.
     63     */
     64     static SkXfermode* CreateXfermode(Mode mode);
     65 
     66     /** Return a function pointer to a routine that applies the specified
     67         porter-duff transfer mode.
     68     */
     69     static SkXfermodeProc GetXfermodeProc(Mode mode);
     70 
     71     /** Return a function pointer to a routine that applies the specified
     72         porter-duff transfer mode and srcColor to a 16bit device color. Note,
     73         if the mode+srcColor might return a non-opaque color, then there is not
     74         16bit proc, and this will return NULL.
     75     */
     76     static SkXfermodeProc16 GetXfermodeProc16(Mode mode, SkColor srcColor);
     77 
     78     /** If the specified xfermode advertises itself as one of the porterduff
     79         modes (via SkXfermode::Coeff), return true and if not null, set mode
     80         to the corresponding porterduff mode. If it is not recognized as a one,
     81         return false and ignore the mode parameter.
     82     */
     83     static bool IsMode(SkXfermode*, Mode* mode);
     84 
     85     /** Return the corersponding SkXfermode::Mode
     86      */
     87     static SkXfermode::Mode ToXfermodeMode(Mode);
     88 };
     89 
     90 #endif
     91 
     92