2 * Copyright 2012 Google Inc.
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
8 #ifndef GrConfigConversionEffect_DEFINED
9 #define GrConfigConversionEffect_DEFINED
11 #include "GrSingleTextureEffect.h"
13 class GrFragmentStage;
14 class GrGLConfigConversionEffect;
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
22 class GrConfigConversionEffect : public GrSingleTextureEffect {
25 * The PM->UPM or UPM->PM conversions to apply.
28 kNone_PMConversion = 0,
29 kMulByAlpha_RoundUp_PMConversion,
30 kMulByAlpha_RoundDown_PMConversion,
31 kDivByAlpha_RoundUp_PMConversion,
32 kDivByAlpha_RoundDown_PMConversion,
37 // Installs an effect in the GrProcessorStage to perform a config conversion.
38 static const GrFragmentProcessor* Create(GrTexture*, bool swapRedAndBlue, PMConversion,
41 static const char* Name() { return "Config Conversion"; }
42 typedef GrGLConfigConversionEffect GLProcessor;
44 virtual const GrBackendFragmentProcessorFactory& getFactory() const SK_OVERRIDE;
46 bool swapsRedAndBlue() const { return fSwapRedAndBlue; }
47 PMConversion pmConversion() const { return fPMConversion; }
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);
59 GrConfigConversionEffect(GrTexture*,
61 PMConversion pmConversion,
62 const SkMatrix& matrix);
64 virtual bool onIsEqual(const GrFragmentProcessor&) const SK_OVERRIDE;
66 virtual void onComputeInvariantOutput(InvariantOutput* inout) const SK_OVERRIDE;
69 PMConversion fPMConversion;
71 GR_DECLARE_FRAGMENT_PROCESSOR_TEST;
73 typedef GrSingleTextureEffect INHERITED;