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/*
* Copyright 2006 The Android Open Source Project
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef SkXfermodePriv_DEFINED
#define SkXfermodePriv_DEFINED
#include "SkBlendMode.h"
#include "SkColor.h"
#include "SkRefCnt.h"
class GrFragmentProcessor;
class GrTexture;
class GrXPFactory;
class SkRasterPipeline;
class SkString;
class SkXfermode : public SkRefCnt {
public:
virtual void xfer32(SkPMColor dst[], const SkPMColor src[], int count,
const SkAlpha aa[]) const = 0;
/**
* If the xfermode is one of the modes in the Mode enum, then asMode()
* returns true and sets (if not null) mode accordingly. Otherwise it
* returns false and ignores the mode parameter.
*/
virtual bool asMode(SkBlendMode* mode) const;
/** Return an SkXfermode object for the specified mode.
*/
static sk_sp<SkXfermode> Make(SkBlendMode);
/**
* Skia maintains global xfermode objects corresponding to each BlendMode. This returns a
* ptr to that global xfermode (or null if the mode is srcover). Thus the caller may use
* the returned ptr, but it should leave its refcnt untouched.
*/
static SkXfermode* Peek(SkBlendMode mode) {
sk_sp<SkXfermode> xfer = Make(mode);
if (!xfer) {
SkASSERT(SkBlendMode::kSrcOver == mode);
return nullptr;
}
SkASSERT(!xfer->unique());
return xfer.get();
}
SkBlendMode blend() const {
SkBlendMode mode;
SkAssertResult(this->asMode(&mode));
return mode;
}
static SkXfermodeProc GetProc(SkBlendMode);
enum SrcColorOpacity {
// The src color is known to be opaque (alpha == 255)
kOpaque_SrcColorOpacity = 0,
// The src color is known to be fully transparent (color == 0)
kTransparentBlack_SrcColorOpacity = 1,
// The src alpha is known to be fully transparent (alpha == 0)
kTransparentAlpha_SrcColorOpacity = 2,
// The src color opacity is unknown
kUnknown_SrcColorOpacity = 3
};
static bool IsOpaque(SkBlendMode, SrcColorOpacity);
#if SK_SUPPORT_GPU
/** Used by the SkXfermodeImageFilter to blend two colors via a GrFragmentProcessor.
The input to the returned FP is the src color. The dst color is
provided by the dst param which becomes a child FP of the returned FP.
It is legal for the function to return a null output. This indicates that
the output of the blend is simply the src color.
*/
virtual sk_sp<GrFragmentProcessor> makeFragmentProcessorForImageFilter(
sk_sp<GrFragmentProcessor> dst) const;
/** A subclass must implement this factory function to work with the GPU backend.
The xfermode will return a factory for which the caller will get a ref. It is up
to the caller to install it. XferProcessors cannot use a background texture.
*/
virtual const GrXPFactory* asXPFactory() const;
#endif
protected:
SkXfermode() {}
virtual ~SkXfermode() {}
private:
};
#endif
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