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 SkXfermode_DEFINED 11 #define SkXfermode_DEFINED 12 13 #include "SkFlattenable.h" 14 #include "SkColor.h" 15 16 class GrEffectRef; 17 class GrTexture; 18 class SkString; 19 20 /** \class SkXfermode 21 * 22 * SkXfermode is the base class for objects that are called to implement custom 23 * "transfer-modes" in the drawing pipeline. The static function Create(Modes) 24 * can be called to return an instance of any of the predefined subclasses as 25 * specified in the Modes enum. When an SkXfermode is assigned to an SkPaint, 26 * then objects drawn with that paint have the xfermode applied. 27 * 28 * All subclasses are required to be reentrant-safe : it must be legal to share 29 * the same instance between several threads. 30 */ 31 class SK_API SkXfermode : public SkFlattenable { 32 public: 33 SK_DECLARE_INST_COUNT(SkXfermode) 34 35 SkXfermode() {} 36 37 virtual void xfer32(SkPMColor dst[], const SkPMColor src[], int count, 38 const SkAlpha aa[]) const; 39 virtual void xfer16(uint16_t dst[], const SkPMColor src[], int count, 40 const SkAlpha aa[]) const; 41 virtual void xferA8(SkAlpha dst[], const SkPMColor src[], int count, 42 const SkAlpha aa[]) const; 43 44 /** Enum of possible coefficients to describe some xfermodes 45 */ 46 enum Coeff { 47 kZero_Coeff, /** 0 */ 48 kOne_Coeff, /** 1 */ 49 kSC_Coeff, /** src color */ 50 kISC_Coeff, /** inverse src color (i.e. 1 - sc) */ 51 kDC_Coeff, /** dst color */ 52 kIDC_Coeff, /** inverse dst color (i.e. 1 - dc) */ 53 kSA_Coeff, /** src alpha */ 54 kISA_Coeff, /** inverse src alpha (i.e. 1 - sa) */ 55 kDA_Coeff, /** dst alpha */ 56 kIDA_Coeff, /** inverse dst alpha (i.e. 1 - da) */ 57 58 kCoeffCount 59 }; 60 61 /** If the xfermode can be expressed as an equation using the coefficients 62 in Coeff, then asCoeff() returns true, and sets (if not null) src and 63 dst accordingly. 64 65 result = src_coeff * src_color + dst_coeff * dst_color; 66 67 As examples, here are some of the porterduff coefficients 68 69 MODE SRC_COEFF DST_COEFF 70 clear zero zero 71 src one zero 72 dst zero one 73 srcover one isa 74 dstover ida one 75 */ 76 virtual bool asCoeff(Coeff* src, Coeff* dst) const; 77 78 /** 79 * The same as calling xfermode->asCoeff(..), except that this also checks 80 * if the xfermode is NULL, and if so, treats it as kSrcOver_Mode. 81 */ 82 static bool AsCoeff(const SkXfermode*, Coeff* src, Coeff* dst); 83 84 /** List of predefined xfermodes. 85 The algebra for the modes uses the following symbols: 86 Sa, Sc - source alpha and color 87 Da, Dc - destination alpha and color (before compositing) 88 [a, c] - Resulting (alpha, color) values 89 For these equations, the colors are in premultiplied state. 90 If no xfermode is specified, kSrcOver is assumed. 91 The modes are ordered by those that can be expressed as a pair of Coeffs, followed by those 92 that aren't Coeffs but have separable r,g,b computations, and finally 93 those that are not separable. 94 */ 95 enum Mode { 96 kClear_Mode, //!< [0, 0] 97 kSrc_Mode, //!< [Sa, Sc] 98 kDst_Mode, //!< [Da, Dc] 99 kSrcOver_Mode, //!< [Sa + Da - Sa*Da, Rc = Sc + (1 - Sa)*Dc] 100 kDstOver_Mode, //!< [Sa + Da - Sa*Da, Rc = Dc + (1 - Da)*Sc] 101 kSrcIn_Mode, //!< [Sa * Da, Sc * Da] 102 kDstIn_Mode, //!< [Sa * Da, Sa * Dc] 103 kSrcOut_Mode, //!< [Sa * (1 - Da), Sc * (1 - Da)] 104 kDstOut_Mode, //!< [Da * (1 - Sa), Dc * (1 - Sa)] 105 kSrcATop_Mode, //!< [Da, Sc * Da + (1 - Sa) * Dc] 106 kDstATop_Mode, //!< [Sa, Sa * Dc + Sc * (1 - Da)] 107 kXor_Mode, //!< [Sa + Da - 2 * Sa * Da, Sc * (1 - Da) + (1 - Sa) * Dc] 108 kPlus_Mode, //!< [Sa + Da, Sc + Dc] 109 kModulate_Mode, // multiplies all components (= alpha and color) 110 111 // Following blend modes are defined in the CSS Compositing standard: 112 // https://dvcs.w3.org/hg/FXTF/rawfile/tip/compositing/index.html#blending 113 kScreen_Mode, 114 kLastCoeffMode = kScreen_Mode, 115 116 kOverlay_Mode, 117 kDarken_Mode, 118 kLighten_Mode, 119 kColorDodge_Mode, 120 kColorBurn_Mode, 121 kHardLight_Mode, 122 kSoftLight_Mode, 123 kDifference_Mode, 124 kExclusion_Mode, 125 kMultiply_Mode, 126 kLastSeparableMode = kMultiply_Mode, 127 128 kHue_Mode, 129 kSaturation_Mode, 130 kColor_Mode, 131 kLuminosity_Mode, 132 kLastMode = kLuminosity_Mode 133 }; 134 135 /** 136 * Gets the name of the Mode as a string. 137 */ 138 static const char* ModeName(Mode); 139 140 /** 141 * If the xfermode is one of the modes in the Mode enum, then asMode() 142 * returns true and sets (if not null) mode accordingly. Otherwise it 143 * returns false and ignores the mode parameter. 144 */ 145 virtual bool asMode(Mode* mode) const; 146 147 /** 148 * The same as calling xfermode->asMode(mode), except that this also checks 149 * if the xfermode is NULL, and if so, treats it as kSrcOver_Mode. 150 */ 151 static bool AsMode(const SkXfermode*, Mode* mode); 152 153 /** 154 * Returns true if the xfermode claims to be the specified Mode. This works 155 * correctly even if the xfermode is NULL (which equates to kSrcOver.) Thus 156 * you can say this without checking for a null... 157 * 158 * If (SkXfermode::IsMode(paint.getXfermode(), 159 * SkXfermode::kDstOver_Mode)) { 160 * ... 161 * } 162 */ 163 static bool IsMode(const SkXfermode* xfer, Mode mode); 164 165 /** Return an SkXfermode object for the specified mode. 166 */ 167 static SkXfermode* Create(Mode mode); 168 169 /** Return a function pointer to a routine that applies the specified 170 porter-duff transfer mode. 171 */ 172 static SkXfermodeProc GetProc(Mode mode); 173 174 /** Return a function pointer to a routine that applies the specified 175 porter-duff transfer mode and srcColor to a 16bit device color. Note, 176 if the mode+srcColor might return a non-opaque color, then there is not 177 16bit proc, and this will return NULL. 178 */ 179 static SkXfermodeProc16 GetProc16(Mode mode, SkColor srcColor); 180 181 /** 182 * If the specified mode can be represented by a pair of Coeff, then return 183 * true and set (if not NULL) the corresponding coeffs. If the mode is 184 * not representable as a pair of Coeffs, return false and ignore the 185 * src and dst parameters. 186 */ 187 static bool ModeAsCoeff(Mode mode, Coeff* src, Coeff* dst); 188 189 SK_ATTR_DEPRECATED("use AsMode(...)") 190 static bool IsMode(const SkXfermode* xfer, Mode* mode) { 191 return AsMode(xfer, mode); 192 } 193 194 /** A subclass may implement this factory function to work with the GPU backend. It is legal 195 to call this with all params NULL to simply test the return value. If effect is non-NULL 196 then the xfermode may optionally allocate an effect to return and the caller as *effect. 197 The caller will install it and own a ref to it. Since the xfermode may or may not assign 198 *effect, the caller should set *effect to NULL beforehand. background specifies the 199 texture to use as the background for compositing, and should be accessed in the effect's 200 fragment shader. If NULL, the effect should request access to destination color 201 (setWillReadDstColor()), and use that in the fragment shader (builder->dstColor()). 202 */ 203 virtual bool asNewEffect(GrEffectRef** effect, GrTexture* background = NULL) const; 204 205 /** Returns true if the xfermode can be expressed as coeffs (src, dst), or as an effect 206 (effect). This helper calls the asCoeff() and asNewEffect() virtuals. If the xfermode is 207 NULL, it is treated as kSrcOver_Mode. It is legal to call this with all params NULL to 208 simply test the return value. effect, src, and dst must all be NULL or all non-NULL. 209 */ 210 static bool AsNewEffectOrCoeff(SkXfermode*, 211 GrEffectRef** effect, 212 Coeff* src, 213 Coeff* dst, 214 GrTexture* background = NULL); 215 216 SkDEVCODE(virtual void toString(SkString* str) const = 0;) 217 SK_DECLARE_FLATTENABLE_REGISTRAR_GROUP() 218 SK_DEFINE_FLATTENABLE_TYPE(SkXfermode) 219 220 protected: 221 SkXfermode(SkFlattenableReadBuffer& rb) : SkFlattenable(rb) {} 222 223 /** The default implementation of xfer32/xfer16/xferA8 in turn call this 224 method, 1 color at a time (upscaled to a SkPMColor). The default 225 implmentation of this method just returns dst. If performance is 226 important, your subclass should override xfer32/xfer16/xferA8 directly. 227 228 This method will not be called directly by the client, so it need not 229 be implemented if your subclass has overridden xfer32/xfer16/xferA8 230 */ 231 virtual SkPMColor xferColor(SkPMColor src, SkPMColor dst) const; 232 233 private: 234 enum { 235 kModeCount = kLastMode + 1 236 }; 237 238 friend class SkGraphics; 239 static void Term(); 240 241 typedef SkFlattenable INHERITED; 242 }; 243 244 /////////////////////////////////////////////////////////////////////////////// 245 246 /** \class SkProcXfermode 247 248 SkProcXfermode is a xfermode that applies the specified proc to its colors. 249 This class is not exported to java. 250 */ 251 class SkProcXfermode : public SkXfermode { 252 public: 253 SkProcXfermode(SkXfermodeProc proc) : fProc(proc) {} 254 255 // overrides from SkXfermode 256 virtual void xfer32(SkPMColor dst[], const SkPMColor src[], int count, 257 const SkAlpha aa[]) const SK_OVERRIDE; 258 virtual void xfer16(uint16_t dst[], const SkPMColor src[], int count, 259 const SkAlpha aa[]) const SK_OVERRIDE; 260 virtual void xferA8(SkAlpha dst[], const SkPMColor src[], int count, 261 const SkAlpha aa[]) const SK_OVERRIDE; 262 263 SK_DEVELOPER_TO_STRING() 264 SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkProcXfermode) 265 266 protected: 267 SkProcXfermode(SkFlattenableReadBuffer&); 268 virtual void flatten(SkFlattenableWriteBuffer&) const SK_OVERRIDE; 269 270 // allow subclasses to update this after we unflatten 271 void setProc(SkXfermodeProc proc) { 272 fProc = proc; 273 } 274 275 SkXfermodeProc getProc() const { 276 return fProc; 277 } 278 279 private: 280 SkXfermodeProc fProc; 281 282 typedef SkXfermode INHERITED; 283 }; 284 285 #endif 286
