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 GrFragmentStage; 14 class GrInvariantOutput; 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 static const GrFragmentProcessor* Create(GrTexture*, bool swapRedAndBlue, PMConversion, 38 const SkMatrix&); 39 name()40 const char* name() const override { return "Config Conversion"; } 41 42 void getGLProcessorKey(const GrGLSLCaps&, GrProcessorKeyBuilder*) const override; 43 44 GrGLFragmentProcessor* createGLInstance() const override; 45 swapsRedAndBlue()46 bool swapsRedAndBlue() const { return fSwapRedAndBlue; } pmConversion()47 PMConversion pmConversion() const { return fPMConversion; } 48 49 // This function determines whether it is possible to choose PM->UPM and UPM->PM conversions 50 // for which in any PM->UPM->PM->UPM sequence the two UPM values are the same. This means that 51 // if pixels are read back to a UPM buffer, written back to PM to the GPU, and read back again 52 // both reads will produce the same result. This test is quite expensive and should not be run 53 // multiple times for a given context. 54 static void TestForPreservingPMConversions(GrContext* context, 55 PMConversion* PMToUPMRule, 56 PMConversion* UPMToPMRule); 57 58 private: 59 GrConfigConversionEffect(GrTexture*, 60 bool swapRedAndBlue, 61 PMConversion pmConversion, 62 const SkMatrix& matrix); 63 64 bool onIsEqual(const GrFragmentProcessor&) const override; 65 66 void onComputeInvariantOutput(GrInvariantOutput* inout) const override; 67 68 bool fSwapRedAndBlue; 69 PMConversion fPMConversion; 70 71 GR_DECLARE_FRAGMENT_PROCESSOR_TEST; 72 73 typedef GrSingleTextureEffect INHERITED; 74 }; 75 76 #endif 77