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