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