michael@0: /*
michael@0:  * Copyright 2012 Google Inc.
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 GrConfigConversionEffect_DEFINED
michael@0: #define GrConfigConversionEffect_DEFINED
michael@0: 
michael@0: #include "GrSingleTextureEffect.h"
michael@0: 
michael@0: class GrEffectStage;
michael@0: class GrGLConfigConversionEffect;
michael@0: 
michael@0: /**
michael@0:  * This class is used to perform config conversions. Clients may want to read/write data that is
michael@0:  * unpremultiplied. Also on some systems reading/writing BGRA or RGBA is faster. In those cases we
michael@0:  * read/write using the faster path and perform an R/B swap in the shader if the client data is in
michael@0:  * the slower config.
michael@0:  */
michael@0: class GrConfigConversionEffect : public GrSingleTextureEffect {
michael@0: public:
michael@0:     /**
michael@0:      * The PM->UPM or UPM->PM conversions to apply.
michael@0:      */
michael@0:     enum PMConversion {
michael@0:         kNone_PMConversion = 0,
michael@0:         kMulByAlpha_RoundUp_PMConversion,
michael@0:         kMulByAlpha_RoundDown_PMConversion,
michael@0:         kDivByAlpha_RoundUp_PMConversion,
michael@0:         kDivByAlpha_RoundDown_PMConversion,
michael@0: 
michael@0:         kPMConversionCnt
michael@0:     };
michael@0: 
michael@0:     // Installs an effect in the GrEffectStage to perform a config conversion.
michael@0:     static const GrEffectRef* Create(GrTexture*,
michael@0:                                      bool swapRedAndBlue,
michael@0:                                      PMConversion pmConversion,
michael@0:                                      const SkMatrix& matrix);
michael@0: 
michael@0:     static const char* Name() { return "Config Conversion"; }
michael@0:     typedef GrGLConfigConversionEffect GLEffect;
michael@0: 
michael@0:     virtual const GrBackendEffectFactory& getFactory() const SK_OVERRIDE;
michael@0: 
michael@0:     virtual void getConstantColorComponents(GrColor* color, uint32_t* validFlags) const SK_OVERRIDE;
michael@0: 
michael@0:     bool swapsRedAndBlue() const { return fSwapRedAndBlue; }
michael@0:     PMConversion  pmConversion() const { return fPMConversion; }
michael@0: 
michael@0:     // This function determines whether it is possible to choose PM->UPM and UPM->PM conversions
michael@0:     // for which in any PM->UPM->PM->UPM sequence the two UPM values are the same. This means that
michael@0:     // if pixels are read back to a UPM buffer, written back to PM to the GPU, and read back again
michael@0:     // both reads will produce the same result. This test is quite expensive and should not be run
michael@0:     // multiple times for a given context.
michael@0:     static void TestForPreservingPMConversions(GrContext* context,
michael@0:                                                PMConversion* PMToUPMRule,
michael@0:                                                PMConversion* UPMToPMRule);
michael@0: 
michael@0: private:
michael@0:     GrConfigConversionEffect(GrTexture*,
michael@0:                             bool swapRedAndBlue,
michael@0:                             PMConversion pmConversion,
michael@0:                             const SkMatrix& matrix);
michael@0: 
michael@0:     virtual bool onIsEqual(const GrEffect&) const SK_OVERRIDE;
michael@0: 
michael@0:     bool            fSwapRedAndBlue;
michael@0:     PMConversion    fPMConversion;
michael@0: 
michael@0:     GR_DECLARE_EFFECT_TEST;
michael@0: 
michael@0:     typedef GrSingleTextureEffect INHERITED;
michael@0: };
michael@0: 
michael@0: #endif