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/*
* Copyright 2011 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef GrPaint_DEFINED
#define GrPaint_DEFINED
#include "GrColor.h"
#include "GrFragmentStage.h"
#include "GrXferProcessor.h"
#include "effects/GrPorterDuffXferProcessor.h"
#include "SkRegion.h"
#include "SkXfermode.h"
/**
* The paint describes how color and coverage are computed at each pixel by GrContext draw
* functions and the how color is blended with the destination pixel.
*
* The paint allows installation of custom color and coverage stages. New types of stages are
* created by subclassing GrProcessor.
*
* The primitive color computation starts with the color specified by setColor(). This color is the
* input to the first color stage. Each color stage feeds its output to the next color stage.
*
* Fractional pixel coverage follows a similar flow. The coverage is initially the value specified
* by setCoverage(). This is input to the first coverage stage. Coverage stages are chained
* together in the same manner as color stages. The output of the last stage is modulated by any
* fractional coverage produced by anti-aliasing. This last step produces the final coverage, C.
*
* setXPFactory is used to control blending between the output color and dest. It also implements
* the application of fractional coverage from the coverage pipeline.
*/
class GrPaint {
public:
GrPaint();
GrPaint(const GrPaint& paint) { *this = paint; }
~GrPaint() {}
/**
* The initial color of the drawn primitive. Defaults to solid white.
*/
void setColor(GrColor color) { fColor = color; }
GrColor getColor() const { return fColor; }
/**
* Should primitives be anti-aliased or not. Defaults to false.
*/
void setAntiAlias(bool aa) { fAntiAlias = aa; }
bool isAntiAlias() const { return fAntiAlias; }
/**
* Should dithering be applied. Defaults to false.
*/
void setDither(bool dither) { fDither = dither; }
bool isDither() const { return fDither; }
const GrXPFactory* setXPFactory(const GrXPFactory* xpFactory) {
fXPFactory.reset(SkRef(xpFactory));
return xpFactory;
}
void setPorterDuffXPFactory(SkXfermode::Mode mode) {
fXPFactory.reset(GrPorterDuffXPFactory::Create(mode));
}
void setCoverageSetOpXPFactory(SkRegion::Op regionOp, bool invertCoverage = false);
/**
* Appends an additional color processor to the color computation.
*/
const GrFragmentProcessor* addColorProcessor(const GrFragmentProcessor* fp) {
SkASSERT(fp);
SkNEW_APPEND_TO_TARRAY(&fColorStages, GrFragmentStage, (fp));
return fp;
}
/**
* Appends an additional coverage processor to the coverage computation.
*/
const GrFragmentProcessor* addCoverageProcessor(const GrFragmentProcessor* fp) {
SkASSERT(fp);
SkNEW_APPEND_TO_TARRAY(&fCoverageStages, GrFragmentStage, (fp));
return fp;
}
/**
* Helpers for adding color or coverage effects that sample a texture. The matrix is applied
* to the src space position to compute texture coordinates.
*/
void addColorTextureProcessor(GrTexture*, const SkMatrix&);
void addCoverageTextureProcessor(GrTexture*, const SkMatrix&);
void addColorTextureProcessor(GrTexture*, const SkMatrix&, const GrTextureParams&);
void addCoverageTextureProcessor(GrTexture*, const SkMatrix&, const GrTextureParams&);
int numColorStages() const { return fColorStages.count(); }
int numCoverageStages() const { return fCoverageStages.count(); }
int numTotalStages() const { return this->numColorStages() + this->numCoverageStages(); }
const GrXPFactory* getXPFactory() const {
if (!fXPFactory) {
fXPFactory.reset(GrPorterDuffXPFactory::Create(SkXfermode::kSrc_Mode));
}
return fXPFactory.get();
}
const GrFragmentStage& getColorStage(int s) const { return fColorStages[s]; }
const GrFragmentStage& getCoverageStage(int s) const { return fCoverageStages[s]; }
GrPaint& operator=(const GrPaint& paint) {
fAntiAlias = paint.fAntiAlias;
fDither = paint.fDither;
fColor = paint.fColor;
fColorStages = paint.fColorStages;
fCoverageStages = paint.fCoverageStages;
fXPFactory.reset(SkRef(paint.getXPFactory()));
return *this;
}
/**
* Returns true if the paint's output color will be constant after blending. If the result is
* true, constantColor will be updated to contain the constant color. Note that we can conflate
* coverage and color, so the actual values written to pixels with partial coverage may still
* not seem constant, even if this function returns true.
*/
bool isConstantBlendedColor(GrColor* constantColor) const;
private:
mutable SkAutoTUnref<const GrXPFactory> fXPFactory;
SkSTArray<4, GrFragmentStage> fColorStages;
SkSTArray<2, GrFragmentStage> fCoverageStages;
bool fAntiAlias;
bool fDither;
GrColor fColor;
};
#endif
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