1 2 /* 3 * Copyright 2006 The Android Open Source Project 4 * 5 * Use of this source code is governed by a BSD-style license that can be 6 * found in the LICENSE file. 7 */ 8 9 10 #ifndef SkPorterDuff_DEFINED 11 #define SkPorterDuff_DEFINED 12 13 #include "SkColor.h" 14 #include "SkXfermode.h" 15 16 class SkXfermode; 17 18 /** DEPRECATED - use SkXfermode::Mode instead 19 */ 20 class SkPorterDuff { 21 public: 22 /** List of predefined xfermodes. In general, the algebra for the modes 23 uses the following symbols: 24 Sa, Sc - source alpha and color 25 Da, Dc - destination alpha and color (before compositing) 26 [a, c] - Resulting (alpha, color) values 27 For these equations, the colors are in premultiplied state. 28 If no xfermode is specified, kSrcOver is assumed. 29 */ 30 enum Mode { 31 kClear_Mode, //!< [0, 0] 32 kSrc_Mode, //!< [Sa, Sc] 33 kDst_Mode, //!< [Da, Dc] 34 kSrcOver_Mode, //!< [Sa + Da - Sa*Da, Rc = Sc + (1 - Sa)*Dc] 35 kDstOver_Mode, //!< [Sa + Da - Sa*Da, Rc = Dc + (1 - Da)*Sc] 36 kSrcIn_Mode, //!< [Sa * Da, Sc * Da] 37 kDstIn_Mode, //!< [Sa * Da, Sa * Dc] 38 kSrcOut_Mode, //!< [Sa * (1 - Da), Sc * (1 - Da)] 39 kDstOut_Mode, //!< [Da * (1 - Sa), Dc * (1 - Sa)] 40 kSrcATop_Mode, //!< [Da, Sc * Da + (1 - Sa) * Dc] 41 kDstATop_Mode, //!< [Sa, Sa * Dc + Sc * (1 - Da)] 42 kXor_Mode, //!< [Sa + Da - 2 * Sa * Da, Sc * (1 - Da) + (1 - Sa) * Dc] 43 kDarken_Mode, //!< [Sa + Da - Sa*Da, Sc*(1 - Da) + Dc*(1 - Sa) + min(Sc, Dc)] 44 kLighten_Mode, //!< [Sa + Da - Sa*Da, Sc*(1 - Da) + Dc*(1 - Sa) + max(Sc, Dc)] 45 kMultiply_Mode, //!< [Sa * Da, Sc * Dc] 46 kScreen_Mode, //!< [Sa + Da - Sa * Da, Sc + Dc - Sc * Dc] 47 kAdd_Mode, //!< Saturate(S + D) 48 #ifdef SK_BUILD_FOR_ANDROID 49 kOverlay_Mode, 50 #endif 51 52 kModeCount 53 }; 54 55 /** Return an SkXfermode object for the specified mode. 56 */ 57 static SkXfermode* CreateXfermode(Mode mode); 58 59 /** Return a function pointer to a routine that applies the specified 60 porter-duff transfer mode. 61 */ 62 static SkXfermodeProc GetXfermodeProc(Mode mode); 63 64 /** Return a function pointer to a routine that applies the specified 65 porter-duff transfer mode and srcColor to a 16bit device color. Note, 66 if the mode+srcColor might return a non-opaque color, then there is not 67 16bit proc, and this will return NULL. 68 */ 69 static SkXfermodeProc16 GetXfermodeProc16(Mode mode, SkColor srcColor); 70 71 /** If the specified xfermode advertises itself as one of the porterduff 72 modes (via SkXfermode::Coeff), return true and if not null, set mode 73 to the corresponding porterduff mode. If it is not recognized as a one, 74 return false and ignore the mode parameter. 75 */ 76 static bool IsMode(SkXfermode*, Mode* mode); 77 78 /** Return the corersponding SkXfermode::Mode 79 */ 80 static SkXfermode::Mode ToXfermodeMode(Mode); 81 }; 82 83 #endif 84 85
