| |
| /* |
| * Copyright 2006 The Android Open Source Project |
| * |
| * Use of this source code is governed by a BSD-style license that can be |
| * found in the LICENSE file. |
| */ |
| |
| |
| #ifndef SkXfermode_DEFINED |
| #define SkXfermode_DEFINED |
| |
| #include "SkFlattenable.h" |
| #include "SkColor.h" |
| |
| class SkString; |
| |
| /** \class SkXfermode |
| |
| SkXfermode is the base class for objects that are called to implement custom |
| "transfer-modes" in the drawing pipeline. The static function Create(Modes) |
| can be called to return an instance of any of the predefined subclasses as |
| specified in the Modes enum. When an SkXfermode is assigned to an SkPaint, |
| then objects drawn with that paint have the xfermode applied. |
| */ |
| class SK_API SkXfermode : public SkFlattenable { |
| public: |
| SK_DECLARE_INST_COUNT(SkXfermode) |
| |
| SkXfermode() {} |
| |
| virtual void xfer32(SkPMColor dst[], const SkPMColor src[], int count, |
| const SkAlpha aa[]) const; |
| virtual void xfer16(uint16_t dst[], const SkPMColor src[], int count, |
| const SkAlpha aa[]) const; |
| virtual void xfer4444(uint16_t dst[], const SkPMColor src[], int count, |
| const SkAlpha aa[]) const; |
| virtual void xferA8(SkAlpha dst[], const SkPMColor src[], int count, |
| const SkAlpha aa[]) const; |
| |
| /** Enum of possible coefficients to describe some xfermodes |
| */ |
| enum Coeff { |
| kZero_Coeff, /** 0 */ |
| kOne_Coeff, /** 1 */ |
| kSC_Coeff, /** src color */ |
| kISC_Coeff, /** inverse src color (i.e. 1 - sc) */ |
| kDC_Coeff, /** dst color */ |
| kIDC_Coeff, /** inverse dst color (i.e. 1 - dc) */ |
| kSA_Coeff, /** src alpha */ |
| kISA_Coeff, /** inverse src alpha (i.e. 1 - sa) */ |
| kDA_Coeff, /** dst alpha */ |
| kIDA_Coeff, /** inverse dst alpha (i.e. 1 - da) */ |
| |
| kCoeffCount |
| }; |
| |
| /** If the xfermode can be expressed as an equation using the coefficients |
| in Coeff, then asCoeff() returns true, and sets (if not null) src and |
| dst accordingly. |
| |
| result = src_coeff * src_color + dst_coeff * dst_color; |
| |
| As examples, here are some of the porterduff coefficients |
| |
| MODE SRC_COEFF DST_COEFF |
| clear zero zero |
| src one zero |
| dst zero one |
| srcover one isa |
| dstover ida one |
| */ |
| virtual bool asCoeff(Coeff* src, Coeff* dst) const; |
| |
| /** |
| * The same as calling xfermode->asCoeff(..), except that this also checks |
| * if the xfermode is NULL, and if so, treats its as kSrcOver_Mode. |
| */ |
| static bool AsCoeff(const SkXfermode*, Coeff* src, Coeff* dst); |
| |
| /** List of predefined xfermodes. |
| The algebra for the modes uses the following symbols: |
| Sa, Sc - source alpha and color |
| Da, Dc - destination alpha and color (before compositing) |
| [a, c] - Resulting (alpha, color) values |
| For these equations, the colors are in premultiplied state. |
| If no xfermode is specified, kSrcOver is assumed. |
| */ |
| enum Mode { |
| kClear_Mode, //!< [0, 0] |
| kSrc_Mode, //!< [Sa, Sc] |
| kDst_Mode, //!< [Da, Dc] |
| kSrcOver_Mode, //!< [Sa + Da - Sa*Da, Rc = Sc + (1 - Sa)*Dc] |
| kDstOver_Mode, //!< [Sa + Da - Sa*Da, Rc = Dc + (1 - Da)*Sc] |
| kSrcIn_Mode, //!< [Sa * Da, Sc * Da] |
| kDstIn_Mode, //!< [Sa * Da, Sa * Dc] |
| kSrcOut_Mode, //!< [Sa * (1 - Da), Sc * (1 - Da)] |
| kDstOut_Mode, //!< [Da * (1 - Sa), Dc * (1 - Sa)] |
| kSrcATop_Mode, //!< [Da, Sc * Da + (1 - Sa) * Dc] |
| kDstATop_Mode, //!< [Sa, Sa * Dc + Sc * (1 - Da)] |
| kXor_Mode, //!< [Sa + Da - 2 * Sa * Da, Sc * (1 - Da) + (1 - Sa) * Dc] |
| |
| // all remaining modes are defined in the SVG Compositing standard |
| // http://www.w3.org/TR/2009/WD-SVGCompositing-20090430/ |
| kPlus_Mode, |
| kModulate_Mode, // multiplies all components (= alpha and color) |
| |
| // all above modes can be expressed as pair of src/dst Coeffs |
| kCoeffModesCnt, |
| |
| kScreen_Mode = kCoeffModesCnt, |
| kOverlay_Mode, |
| kDarken_Mode, |
| kLighten_Mode, |
| kColorDodge_Mode, |
| kColorBurn_Mode, |
| kHardLight_Mode, |
| kSoftLight_Mode, |
| kDifference_Mode, |
| kExclusion_Mode, |
| |
| kLastMode = kExclusion_Mode |
| }; |
| |
| /** |
| * If the xfermode is one of the modes in the Mode enum, then asMode() |
| * returns true and sets (if not null) mode accordingly. Otherwise it |
| * returns false and ignores the mode parameter. |
| */ |
| virtual bool asMode(Mode* mode) const; |
| |
| /** |
| * The same as calling xfermode->asMode(mode), except that this also checks |
| * if the xfermode is NULL, and if so, treats its as kSrcOver_Mode. |
| */ |
| static bool AsMode(const SkXfermode*, Mode* mode); |
| |
| /** |
| * Returns true if the xfermode claims to be the specified Mode. This works |
| * correctly even if the xfermode is NULL (which equates to kSrcOver.) Thus |
| * you can say this without checking for a null... |
| * |
| * If (SkXfermode::IsMode(paint.getXfermode(), |
| * SkXfermode::kDstOver_Mode)) { |
| * ... |
| * } |
| */ |
| static bool IsMode(const SkXfermode* xfer, Mode mode); |
| |
| /** Return an SkXfermode object for the specified mode. |
| */ |
| static SkXfermode* Create(Mode mode); |
| |
| /** Return a function pointer to a routine that applies the specified |
| porter-duff transfer mode. |
| */ |
| static SkXfermodeProc GetProc(Mode mode); |
| |
| /** Return a function pointer to a routine that applies the specified |
| porter-duff transfer mode and srcColor to a 16bit device color. Note, |
| if the mode+srcColor might return a non-opaque color, then there is not |
| 16bit proc, and this will return NULL. |
| */ |
| static SkXfermodeProc16 GetProc16(Mode mode, SkColor srcColor); |
| |
| /** |
| * If the specified mode can be represented by a pair of Coeff, then return |
| * true and set (if not NULL) the corresponding coeffs. If the mode is |
| * not representable as a pair of Coeffs, return false and ignore the |
| * src and dst parameters. |
| */ |
| static bool ModeAsCoeff(Mode mode, Coeff* src, Coeff* dst); |
| |
| // DEPRECATED: call AsMode(...) |
| static bool IsMode(const SkXfermode* xfer, Mode* mode) { |
| return AsMode(xfer, mode); |
| } |
| |
| SkDEVCODE(virtual void toString(SkString* str) const = 0;) |
| SK_DECLARE_FLATTENABLE_REGISTRAR_GROUP() |
| protected: |
| SkXfermode(SkFlattenableReadBuffer& rb) : SkFlattenable(rb) {} |
| |
| /** The default implementation of xfer32/xfer16/xferA8 in turn call this |
| method, 1 color at a time (upscaled to a SkPMColor). The default |
| implmentation of this method just returns dst. If performance is |
| important, your subclass should override xfer32/xfer16/xferA8 directly. |
| |
| This method will not be called directly by the client, so it need not |
| be implemented if your subclass has overridden xfer32/xfer16/xferA8 |
| */ |
| virtual SkPMColor xferColor(SkPMColor src, SkPMColor dst) const; |
| |
| private: |
| enum { |
| kModeCount = kLastMode + 1 |
| }; |
| typedef SkFlattenable INHERITED; |
| }; |
| |
| /////////////////////////////////////////////////////////////////////////////// |
| |
| /** \class SkProcXfermode |
| |
| SkProcXfermode is a xfermode that applies the specified proc to its colors. |
| This class is not exported to java. |
| */ |
| class SkProcXfermode : public SkXfermode { |
| public: |
| SkProcXfermode(SkXfermodeProc proc) : fProc(proc) {} |
| |
| // overrides from SkXfermode |
| virtual void xfer32(SkPMColor dst[], const SkPMColor src[], int count, |
| const SkAlpha aa[]) const SK_OVERRIDE; |
| virtual void xfer16(uint16_t dst[], const SkPMColor src[], int count, |
| const SkAlpha aa[]) const SK_OVERRIDE; |
| virtual void xfer4444(uint16_t dst[], const SkPMColor src[], int count, |
| const SkAlpha aa[]) const SK_OVERRIDE; |
| virtual void xferA8(SkAlpha dst[], const SkPMColor src[], int count, |
| const SkAlpha aa[]) const SK_OVERRIDE; |
| |
| SK_DEVELOPER_TO_STRING() |
| SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkProcXfermode) |
| |
| protected: |
| SkProcXfermode(SkFlattenableReadBuffer&); |
| virtual void flatten(SkFlattenableWriteBuffer&) const SK_OVERRIDE; |
| |
| // allow subclasses to update this after we unflatten |
| void setProc(SkXfermodeProc proc) { |
| fProc = proc; |
| } |
| |
| private: |
| SkXfermodeProc fProc; |
| |
| typedef SkXfermode INHERITED; |
| }; |
| |
| #endif |
