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 SkXfermodePriv_DEFINED 9 #define SkXfermodePriv_DEFINED 10 11 #include "SkBlendMode.h" 12 #include "SkColor.h" 13 #include "SkFlattenable.h" 14 15 class GrFragmentProcessor; 16 class GrTexture; 17 class GrXPFactory; 18 class SkRasterPipeline; 19 class SkString; 20 21 struct SkArithmeticParams; 22 23 struct SkPM4f; 24 typedef SkPM4f (*SkXfermodeProc4f)(const SkPM4f& src, const SkPM4f& dst); 25 26 /** \class SkXfermode 27 * 28 * SkXfermode is the base class for objects that are called to implement custom 29 * "transfer-modes" in the drawing pipeline. The static function Create(Modes) 30 * can be called to return an instance of any of the predefined subclasses as 31 * specified in the Modes enum. When an SkXfermode is assigned to an SkPaint, 32 * then objects drawn with that paint have the xfermode applied. 33 * 34 * All subclasses are required to be reentrant-safe : it must be legal to share 35 * the same instance between several threads. 36 */ 37 class SK_API SkXfermode : public SkFlattenable { 38 public: 39 virtual void xfer32(SkPMColor dst[], const SkPMColor src[], int count, 40 const SkAlpha aa[]) const; 41 virtual void xfer16(uint16_t dst[], const SkPMColor src[], int count, 42 const SkAlpha aa[]) const; 43 virtual void xferA8(SkAlpha dst[], const SkPMColor src[], int count, 44 const SkAlpha aa[]) const; 45 46 /** Enum of possible coefficients to describe some xfermodes 47 */ 48 enum Coeff { 49 kZero_Coeff, /** 0 */ 50 kOne_Coeff, /** 1 */ 51 kSC_Coeff, /** src color */ 52 kISC_Coeff, /** inverse src color (i.e. 1 - sc) */ 53 kDC_Coeff, /** dst color */ 54 kIDC_Coeff, /** inverse dst color (i.e. 1 - dc) */ 55 kSA_Coeff, /** src alpha */ 56 kISA_Coeff, /** inverse src alpha (i.e. 1 - sa) */ 57 kDA_Coeff, /** dst alpha */ 58 kIDA_Coeff, /** inverse dst alpha (i.e. 1 - da) */ 59 60 kCoeffCount 61 }; 62 63 /** List of predefined xfermodes. 64 The algebra for the modes uses the following symbols: 65 Sa, Sc - source alpha and color 66 Da, Dc - destination alpha and color (before compositing) 67 [a, c] - Resulting (alpha, color) values 68 For these equations, the colors are in premultiplied state. 69 If no xfermode is specified, kSrcOver is assumed. 70 The modes are ordered by those that can be expressed as a pair of Coeffs, followed by those 71 that aren't Coeffs but have separable r,g,b computations, and finally 72 those that are not separable. 73 */ 74 enum Mode { 75 kClear_Mode, //!< [0, 0] 76 kSrc_Mode, //!< [Sa, Sc] 77 kDst_Mode, //!< [Da, Dc] 78 kSrcOver_Mode, //!< [Sa + Da * (1 - Sa), Sc + Dc * (1 - Sa)] 79 kDstOver_Mode, //!< [Da + Sa * (1 - Da), Dc + Sc * (1 - Da)] 80 kSrcIn_Mode, //!< [Sa * Da, Sc * Da] 81 kDstIn_Mode, //!< [Da * Sa, Dc * Sa] 82 kSrcOut_Mode, //!< [Sa * (1 - Da), Sc * (1 - Da)] 83 kDstOut_Mode, //!< [Da * (1 - Sa), Dc * (1 - Sa)] 84 kSrcATop_Mode, //!< [Da, Sc * Da + Dc * (1 - Sa)] 85 kDstATop_Mode, //!< [Sa, Dc * Sa + Sc * (1 - Da)] 86 kXor_Mode, //!< [Sa + Da - 2 * Sa * Da, Sc * (1 - Da) + Dc * (1 - Sa)] 87 kPlus_Mode, //!< [Sa + Da, Sc + Dc] 88 kModulate_Mode, // multiplies all components (= alpha and color) 89 90 // Following blend modes are defined in the CSS Compositing standard: 91 // https://dvcs.w3.org/hg/FXTF/rawfile/tip/compositing/index.html#blending 92 kScreen_Mode, 93 kLastCoeffMode = kScreen_Mode, 94 95 kOverlay_Mode, 96 kDarken_Mode, 97 kLighten_Mode, 98 kColorDodge_Mode, 99 kColorBurn_Mode, 100 kHardLight_Mode, 101 kSoftLight_Mode, 102 kDifference_Mode, 103 kExclusion_Mode, 104 kMultiply_Mode, 105 kLastSeparableMode = kMultiply_Mode, 106 107 kHue_Mode, 108 kSaturation_Mode, 109 kColor_Mode, 110 kLuminosity_Mode, 111 kLastMode = kLuminosity_Mode 112 }; 113 114 /** 115 * Gets the name of the Mode as a string. 116 */ 117 static const char* ModeName(Mode); 118 static const char* ModeName(SkBlendMode mode) { 119 return ModeName(Mode(mode)); 120 } 121 122 /** 123 * If the xfermode is one of the modes in the Mode enum, then asMode() 124 * returns true and sets (if not null) mode accordingly. Otherwise it 125 * returns false and ignores the mode parameter. 126 */ 127 virtual bool asMode(Mode* mode) const; 128 129 /** 130 * The same as calling xfermode->asMode(mode), except that this also checks 131 * if the xfermode is NULL, and if so, treats it as kSrcOver_Mode. 132 */ 133 static bool AsMode(const SkXfermode*, Mode* mode); 134 static bool AsMode(const sk_sp<SkXfermode>& xfer, Mode* mode) { 135 return AsMode(xfer.get(), mode); 136 } 137 138 /** 139 * Returns true if the xfermode claims to be the specified Mode. This works 140 * correctly even if the xfermode is NULL (which equates to kSrcOver.) Thus 141 * you can say this without checking for a null... 142 * 143 * If (SkXfermode::IsMode(paint.getXfermode(), 144 * SkXfermode::kDstOver_Mode)) { 145 * ... 146 * } 147 */ 148 static bool IsMode(const SkXfermode* xfer, Mode mode); 149 static bool IsMode(const sk_sp<SkXfermode>& xfer, Mode mode) { 150 return IsMode(xfer.get(), mode); 151 } 152 153 /** Return an SkXfermode object for the specified mode. 154 */ 155 static sk_sp<SkXfermode> Make(SkBlendMode); 156 static sk_sp<SkXfermode> Make(Mode m) { return Make((SkBlendMode)m); } 157 158 /** 159 * Skia maintains global xfermode objects corresponding to each BlendMode. This returns a 160 * ptr to that global xfermode (or null if the mode is srcover). Thus the caller may use 161 * the returned ptr, but it should leave its refcnt untouched. 162 */ 163 static SkXfermode* Peek(SkBlendMode mode) { 164 sk_sp<SkXfermode> xfer = Make(mode); 165 if (!xfer) { 166 SkASSERT(SkBlendMode::kSrcOver == mode); 167 return nullptr; 168 } 169 SkASSERT(!xfer->unique()); 170 return xfer.get(); 171 } 172 173 SkBlendMode blend() const { 174 Mode mode; 175 SkAssertResult(this->asMode(&mode)); 176 return (SkBlendMode)mode; 177 } 178 179 static SkXfermodeProc GetProc(SkBlendMode); 180 static SkXfermodeProc4f GetProc4f(SkBlendMode); 181 182 /** 183 * If the specified mode can be represented by a pair of Coeff, then return 184 * true and set (if not NULL) the corresponding coeffs. If the mode is 185 * not representable as a pair of Coeffs, return false and ignore the 186 * src and dst parameters. 187 */ 188 static bool ModeAsCoeff(Mode mode, Coeff* src, Coeff* dst); 189 static bool ModeAsCoeff(SkBlendMode mode, Coeff* src, Coeff* dst) { 190 return ModeAsCoeff((Mode)mode, src, dst); 191 } 192 193 /** 194 * Returns whether or not the xfer mode can support treating coverage as alpha 195 */ 196 virtual bool supportsCoverageAsAlpha() const; 197 198 /** 199 * The same as calling xfermode->supportsCoverageAsAlpha(), except that this also checks if 200 * the xfermode is NULL, and if so, treats it as kSrcOver_Mode. 201 */ 202 static bool SupportsCoverageAsAlpha(const SkXfermode* xfer); 203 static bool SupportsCoverageAsAlpha(const sk_sp<SkXfermode>& xfer) { 204 return SupportsCoverageAsAlpha(xfer.get()); 205 } 206 207 enum SrcColorOpacity { 208 // The src color is known to be opaque (alpha == 255) 209 kOpaque_SrcColorOpacity = 0, 210 // The src color is known to be fully transparent (color == 0) 211 kTransparentBlack_SrcColorOpacity = 1, 212 // The src alpha is known to be fully transparent (alpha == 0) 213 kTransparentAlpha_SrcColorOpacity = 2, 214 // The src color opacity is unknown 215 kUnknown_SrcColorOpacity = 3 216 }; 217 218 /** 219 * Returns whether or not the result of the draw with the xfer mode will be opaque or not. The 220 * input to this call is an enum describing known information about the opacity of the src color 221 * that will be given to the xfer mode. 222 */ 223 virtual bool isOpaque(SrcColorOpacity opacityType) const; 224 225 /** 226 * The same as calling xfermode->isOpaque(...), except that this also checks if 227 * the xfermode is NULL, and if so, treats it as kSrcOver_Mode. 228 */ 229 static bool IsOpaque(const SkXfermode* xfer, SrcColorOpacity opacityType); 230 static bool IsOpaque(const sk_sp<SkXfermode>& xfer, SrcColorOpacity opacityType) { 231 return IsOpaque(xfer.get(), opacityType); 232 } 233 static bool IsOpaque(SkBlendMode, SrcColorOpacity); 234 235 #if SK_SUPPORT_GPU 236 /** Used by the SkXfermodeImageFilter to blend two colors via a GrFragmentProcessor. 237 The input to the returned FP is the src color. The dst color is 238 provided by the dst param which becomes a child FP of the returned FP. 239 It is legal for the function to return a null output. This indicates that 240 the output of the blend is simply the src color. 241 */ 242 virtual sk_sp<GrFragmentProcessor> makeFragmentProcessorForImageFilter( 243 sk_sp<GrFragmentProcessor> dst) const; 244 245 /** A subclass must implement this factory function to work with the GPU backend. 246 The xfermode will return a factory for which the caller will get a ref. It is up 247 to the caller to install it. XferProcessors cannot use a background texture. 248 */ 249 virtual const GrXPFactory* asXPFactory() const; 250 #endif 251 252 SK_TO_STRING_PUREVIRT() 253 SK_DECLARE_FLATTENABLE_REGISTRAR_GROUP() 254 SK_DEFINE_FLATTENABLE_TYPE(SkXfermode) 255 256 enum D32Flags { 257 kSrcIsOpaque_D32Flag = 1 << 0, 258 kSrcIsSingle_D32Flag = 1 << 1, 259 kDstIsSRGB_D32Flag = 1 << 2, 260 }; 261 typedef void (*D32Proc)(SkBlendMode, uint32_t dst[], const SkPM4f src[], 262 int count, const SkAlpha coverage[]); 263 static D32Proc GetD32Proc(SkBlendMode, uint32_t flags); 264 265 enum F16Flags { 266 kSrcIsOpaque_F16Flag = 1 << 0, 267 kSrcIsSingle_F16Flag = 1 << 1, 268 }; 269 typedef void (*F16Proc)(SkBlendMode, uint64_t dst[], const SkPM4f src[], int count, 270 const SkAlpha coverage[]); 271 static F16Proc GetF16Proc(SkBlendMode, uint32_t flags); 272 273 enum LCDFlags { 274 kSrcIsOpaque_LCDFlag = 1 << 0, // else src(s) may have alpha < 1 275 kSrcIsSingle_LCDFlag = 1 << 1, // else src[count] 276 kDstIsSRGB_LCDFlag = 1 << 2, // else l32 or f16 277 }; 278 typedef void (*LCD32Proc)(uint32_t* dst, const SkPM4f* src, int count, const uint16_t lcd[]); 279 typedef void (*LCDF16Proc)(uint64_t* dst, const SkPM4f* src, int count, const uint16_t lcd[]); 280 static LCD32Proc GetLCD32Proc(uint32_t flags); 281 static LCDF16Proc GetLCDF16Proc(uint32_t) { return nullptr; } 282 283 virtual bool isArithmetic(SkArithmeticParams*) const { return false; } 284 285 protected: 286 SkXfermode() {} 287 /** The default implementation of xfer32/xfer16/xferA8 in turn call this 288 method, 1 color at a time (upscaled to a SkPMColor). The default 289 implementation of this method just returns dst. If performance is 290 important, your subclass should override xfer32/xfer16/xferA8 directly. 291 292 This method will not be called directly by the client, so it need not 293 be implemented if your subclass has overridden xfer32/xfer16/xferA8 294 */ 295 virtual SkPMColor xferColor(SkPMColor src, SkPMColor dst) const; 296 297 private: 298 enum { 299 kModeCount = kLastMode + 1 300 }; 301 302 typedef SkFlattenable INHERITED; 303 }; 304 305 #endif 306
