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/*
* Copyright 2017 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef GrNonlinearColorSpaceXformEffect_DEFINED
#define GrNonlinearColorSpaceXformEffect_DEFINED
#include "GrFragmentProcessor.h"
#include "SkColorSpace.h"
#include "SkMatrix44.h"
/**
* The output of this effect is the input, transformed into a different color space.
* This effect is used for nonlinear blending color space support - it does not assume HW sRGB
* capabilities, and performs both the source and destination transfer functions numerically in
* the shader. Any parametric transfer function is supported. Because of the nonlinear blending,
* premultiplication is also nonlinear - source pixels are unpremultiplied before the source
* transfer function, and then premultiplied after the destination transfer function.
*/
class GrNonlinearColorSpaceXformEffect : public GrFragmentProcessor {
public:
/**
* The conversion effect is only well defined with a valid source and destination color space.
* This will return nullptr if either space is nullptr, if both spaces are equal, or if either
* space has a non-parametric transfer funcion (e.g. lookup table or A2B).
*/
static sk_sp<GrFragmentProcessor> Make(const SkColorSpace* src, const SkColorSpace* dst);
const char* name() const override { return "NonlinearColorSpaceXform"; }
static const int kNumTransferFnCoeffs = 7;
/**
* Flags that specify which operations are performed for one particular conversion.
* Some color space pairs may not need all operations, if one or both transfer functions
* is linear, or if the gamuts are the same.
*/
enum Ops {
kSrcTransfer_Op = 0x1,
kGamutXform_Op = 0x2,
kDstTransfer_Op = 0x4,
};
uint32_t ops() const { return fOps; }
const float* srcTransferFnCoeffs() const { return fSrcTransferFnCoeffs; }
const float* dstTransferFnCoeffs() const { return fDstTransferFnCoeffs; }
const SkMatrix44& gamutXform() const { return fGamutXform; }
private:
GrNonlinearColorSpaceXformEffect(uint32_t ops,
const SkColorSpaceTransferFn& srcTransferFn,
const SkColorSpaceTransferFn& dstTransferFn,
const SkMatrix44& gamutXform);
GrGLSLFragmentProcessor* onCreateGLSLInstance() const override;
void onGetGLSLProcessorKey(const GrShaderCaps&, GrProcessorKeyBuilder*) const override;
bool onIsEqual(const GrFragmentProcessor&) const override;
float fSrcTransferFnCoeffs[kNumTransferFnCoeffs];
float fDstTransferFnCoeffs[kNumTransferFnCoeffs];
SkMatrix44 fGamutXform;
uint32_t fOps;
GR_DECLARE_FRAGMENT_PROCESSOR_TEST;
typedef GrFragmentProcessor INHERITED;
};
#endif
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