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