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"
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 GrEffectStage to perform a config conversion.
38 static const GrEffect* Create(GrTexture*,
40 PMConversion pmConversion,
41 const SkMatrix& matrix);
43 static const char* Name() { return "Config Conversion"; }
44 typedef GrGLConfigConversionEffect GLEffect;
46 virtual const GrBackendEffectFactory& getFactory() const SK_OVERRIDE;
48 virtual void getConstantColorComponents(GrColor* color, uint32_t* validFlags) const SK_OVERRIDE;
50 bool swapsRedAndBlue() const { return fSwapRedAndBlue; }
51 PMConversion pmConversion() const { return fPMConversion; }
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);
63 GrConfigConversionEffect(GrTexture*,
65 PMConversion pmConversion,
66 const SkMatrix& matrix);
68 virtual bool onIsEqual(const GrEffect&) const SK_OVERRIDE;
71 PMConversion fPMConversion;
73 GR_DECLARE_EFFECT_TEST;
75 typedef GrSingleTextureEffect INHERITED;