michael@0: /*
michael@0:  * Copyright 2006 The Android Open Source Project
michael@0:  *
michael@0:  * Use of this source code is governed by a BSD-style license that can be
michael@0:  * found in the LICENSE file.
michael@0:  */
michael@0: 
michael@0: #ifndef SkPorterDuff_DEFINED
michael@0: #define SkPorterDuff_DEFINED
michael@0: 
michael@0: #include "SkColor.h"
michael@0: #include "SkXfermode.h"
michael@0: 
michael@0: class SkXfermode;
michael@0: 
michael@0: class SK_API SkPorterDuff {
michael@0: public:
michael@0:     /** List of predefined xfermodes. In general, the algebra for the modes
michael@0:         uses the following symbols:
michael@0:         Sa, Sc  - source alpha and color
michael@0:         Da, Dc - destination alpha and color (before compositing)
michael@0:         [a, c] - Resulting (alpha, color) values
michael@0:         For these equations, the colors are in premultiplied state.
michael@0:         If no xfermode is specified, kSrcOver is assumed.
michael@0:     */
michael@0:     enum Mode {
michael@0:         kClear_Mode,    //!< [0, 0]
michael@0:         kSrc_Mode,      //!< [Sa, Sc]
michael@0:         kDst_Mode,      //!< [Da, Dc]
michael@0:         kSrcOver_Mode,  //!< [Sa + Da - Sa*Da, Rc = Sc + (1 - Sa)*Dc]
michael@0:         kDstOver_Mode,  //!< [Sa + Da - Sa*Da, Rc = Dc + (1 - Da)*Sc]
michael@0:         kSrcIn_Mode,    //!< [Sa * Da, Sc * Da]
michael@0:         kDstIn_Mode,    //!< [Sa * Da, Sa * Dc]
michael@0:         kSrcOut_Mode,   //!< [Sa * (1 - Da), Sc * (1 - Da)]
michael@0:         kDstOut_Mode,   //!< [Da * (1 - Sa), Dc * (1 - Sa)]
michael@0:         kSrcATop_Mode,  //!< [Da, Sc * Da + (1 - Sa) * Dc]
michael@0:         kDstATop_Mode,  //!< [Sa, Sa * Dc + Sc * (1 - Da)]
michael@0:         kXor_Mode,      //!< [Sa + Da - 2 * Sa * Da, Sc * (1 - Da) + (1 - Sa) * Dc]
michael@0:         kDarken_Mode,   //!< [Sa + Da - Sa*Da, Sc*(1 - Da) + Dc*(1 - Sa) + min(Sc, Dc)]
michael@0:         kLighten_Mode,  //!< [Sa + Da - Sa*Da, Sc*(1 - Da) + Dc*(1 - Sa) + max(Sc, Dc)]
michael@0:         kModulate_Mode, //!< [Sa * Da, Sc * Dc] multiplies all components
michael@0:         kScreen_Mode,   //!< [Sa + Da - Sa * Da, Sc + Dc - Sc * Dc]
michael@0:         kAdd_Mode,      //!< Saturate(S + D)
michael@0: #ifdef SK_BUILD_FOR_ANDROID
michael@0:         kOverlay_Mode,
michael@0: #endif
michael@0: 
michael@0:         kModeCount
michael@0:     };
michael@0: 
michael@0:     /** Return an SkXfermode object for the specified mode.
michael@0:     */
michael@0:     static SkXfermode* CreateXfermode(Mode mode);
michael@0: 
michael@0:     /** Return a function pointer to a routine that applies the specified
michael@0:         porter-duff transfer mode.
michael@0:     */
michael@0:     static SkXfermodeProc GetXfermodeProc(Mode mode);
michael@0: 
michael@0:     /** Return a function pointer to a routine that applies the specified
michael@0:         porter-duff transfer mode and srcColor to a 16bit device color. Note,
michael@0:         if the mode+srcColor might return a non-opaque color, then there is not
michael@0:         16bit proc, and this will return NULL.
michael@0:     */
michael@0:     static SkXfermodeProc16 GetXfermodeProc16(Mode mode, SkColor srcColor);
michael@0: 
michael@0:     /** If the specified xfermode advertises itself as one of the porterduff
michael@0:         modes (via SkXfermode::Coeff), return true and if not null, set mode
michael@0:         to the corresponding porterduff mode. If it is not recognized as a one,
michael@0:         return false and ignore the mode parameter.
michael@0:     */
michael@0:     static bool IsMode(SkXfermode*, Mode* mode);
michael@0: 
michael@0:     /** Return the corersponding SkXfermode::Mode
michael@0:      */
michael@0:     static SkXfermode::Mode ToXfermodeMode(Mode);
michael@0: } SK_ATTR_DEPRECATED("use SkXfermode::Mode");
michael@0: 
michael@0: #endif