1 /* 2 * Copyright 2012 Google Inc. 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 GrConfigConversionEffect_DEFINED 9 #define GrConfigConversionEffect_DEFINED 10 11 #include "GrSingleTextureEffect.h" 12 13 class GrEffectStage; 14 class GrGLConfigConversionEffect; 15 16 /** 17 * This class is used to perform config conversions. Clients may want to read/write data that is 18 * unpremultiplied. Also on some systems reading/writing BGRA or RGBA is faster. In those cases we 19 * read/write using the faster path and perform an R/B swap in the shader if the client data is in 20 * the slower config. 21 */ 22 class GrConfigConversionEffect : public GrSingleTextureEffect { 23 public: 24 /** 25 * The PM->UPM or UPM->PM conversions to apply. 26 */ 27 enum PMConversion { 28 kNone_PMConversion = 0, 29 kMulByAlpha_RoundUp_PMConversion, 30 kMulByAlpha_RoundDown_PMConversion, 31 kDivByAlpha_RoundUp_PMConversion, 32 kDivByAlpha_RoundDown_PMConversion, 33 34 kPMConversionCnt 35 }; 36 37 // Installs an effect in the GrEffectStage to perform a config conversion. 38 static const GrEffectRef* Create(GrTexture*, 39 bool swapRedAndBlue, 40 PMConversion pmConversion, 41 const SkMatrix& matrix); 42 Name()43 static const char* Name() { return "Config Conversion"; } 44 typedef GrGLConfigConversionEffect GLEffect; 45 46 virtual const GrBackendEffectFactory& getFactory() const SK_OVERRIDE; 47 48 virtual void getConstantColorComponents(GrColor* color, uint32_t* validFlags) const SK_OVERRIDE; 49 swapsRedAndBlue()50 bool swapsRedAndBlue() const { return fSwapRedAndBlue; } pmConversion()51 PMConversion pmConversion() const { return fPMConversion; } 52 53 // This function determines whether it is possible to choose PM->UPM and UPM->PM conversions 54 // for which in any PM->UPM->PM->UPM sequence the two UPM values are the same. This means that 55 // if pixels are read back to a UPM buffer, written back to PM to the GPU, and read back again 56 // both reads will produce the same result. This test is quite expensive and should not be run 57 // multiple times for a given context. 58 static void TestForPreservingPMConversions(GrContext* context, 59 PMConversion* PMToUPMRule, 60 PMConversion* UPMToPMRule); 61 62 private: 63 GrConfigConversionEffect(GrTexture*, 64 bool swapRedAndBlue, 65 PMConversion pmConversion, 66 const SkMatrix& matrix); 67 68 virtual bool onIsEqual(const GrEffect&) const SK_OVERRIDE; 69 70 bool fSwapRedAndBlue; 71 PMConversion fPMConversion; 72 73 GR_DECLARE_EFFECT_TEST; 74 75 typedef GrSingleTextureEffect INHERITED; 76 }; 77 78 #endif 79