Home | History | Annotate | Download | only in gpu 
      1 
      2 /*
      3  * Copyright 2011 Google Inc.
      4  *
      5  * Use of this source code is governed by a BSD-style license that can be
      6  * found in the LICENSE file.
      7  */
      8 
      9 
     10 #ifndef GrPaint_DEFINED
     11 #define GrPaint_DEFINED
     12 
     13 #include "GrColor.h"
     14 #include "GrFragmentProcessor.h"
     15 #include "SkBlendMode.h"
     16 #include "SkRefCnt.h"
     17 #include "SkRegion.h"
     18 #include "SkTLazy.h"
     19 
     20 class GrTextureProxy;
     21 class GrXPFactory;
     22 
     23 /**
     24  * The paint describes how color and coverage are computed at each pixel by GrContext draw
     25  * functions and the how color is blended with the destination pixel.
     26  *
     27  * The paint allows installation of custom color and coverage stages. New types of stages are
     28  * created by subclassing GrProcessor.
     29  *
     30  * The primitive color computation starts with the color specified by setColor(). This color is the
     31  * input to the first color stage. Each color stage feeds its output to the next color stage.
     32  *
     33  * Fractional pixel coverage follows a similar flow. The GrGeometryProcessor (specified elsewhere)
     34  * provides the initial coverage which is passed to the first coverage fragment processor, which
     35  * feeds its output to next coverage fragment processor.
     36  *
     37  * setXPFactory is used to control blending between the output color and dest. It also implements
     38  * the application of fractional coverage from the coverage pipeline.
     39  */
     40 class GrPaint {
     41 public:
     42     GrPaint() = default;
     43     ~GrPaint() = default;
     44 
     45     static GrPaint Clone(const GrPaint& src) { return GrPaint(src); }
     46 
     47     /**
     48      * The initial color of the drawn primitive. Defaults to solid white.
     49      */
     50     void setColor4f(const GrColor4f& color) { fColor = color; }
     51     const GrColor4f& getColor4f() const { return fColor; }
     52 
     53     /**
     54      * Legacy getter, until all code handles 4f directly.
     55      */
     56     GrColor getColor() const { return fColor.toGrColor(); }
     57 
     58     /**
     59      * Should shader output conversion from linear to sRGB be disabled.
     60      * Only relevant if the destination is sRGB. Defaults to false.
     61      */
     62     void setDisableOutputConversionToSRGB(bool srgb) { fDisableOutputConversionToSRGB = srgb; }
     63     bool getDisableOutputConversionToSRGB() const { return fDisableOutputConversionToSRGB; }
     64 
     65     /**
     66      * Should sRGB inputs be allowed to perform sRGB to linear conversion. With this flag
     67      * set to false, sRGB textures will be treated as linear (including filtering).
     68      */
     69     void setAllowSRGBInputs(bool allowSRGBInputs) { fAllowSRGBInputs = allowSRGBInputs; }
     70     bool getAllowSRGBInputs() const { return fAllowSRGBInputs; }
     71 
     72     /**
     73      * Should rendering be gamma-correct, end-to-end. Causes sRGB render targets to behave
     74      * as such (with linear blending), and sRGB inputs to be filtered and decoded correctly.
     75      */
     76     void setGammaCorrect(bool gammaCorrect) {
     77         this->setDisableOutputConversionToSRGB(!gammaCorrect);
     78         this->setAllowSRGBInputs(gammaCorrect);
     79     }
     80 
     81     void setXPFactory(const GrXPFactory* xpFactory) {
     82         fXPFactory = xpFactory;
     83         fTrivial &= !SkToBool(xpFactory);
     84     }
     85 
     86     void setPorterDuffXPFactory(SkBlendMode mode);
     87 
     88     void setCoverageSetOpXPFactory(SkRegion::Op, bool invertCoverage = false);
     89 
     90     /**
     91      * Appends an additional color processor to the color computation.
     92      */
     93     void addColorFragmentProcessor(std::unique_ptr<GrFragmentProcessor> fp) {
     94         SkASSERT(fp);
     95         fColorFragmentProcessors.push_back(std::move(fp));
     96         fTrivial = false;
     97     }
     98 
     99     /**
    100      * Appends an additional coverage processor to the coverage computation.
    101      */
    102     void addCoverageFragmentProcessor(std::unique_ptr<GrFragmentProcessor> fp) {
    103         SkASSERT(fp);
    104         fCoverageFragmentProcessors.push_back(std::move(fp));
    105         fTrivial = false;
    106     }
    107 
    108     /**
    109      * Helpers for adding color or coverage effects that sample a texture. The matrix is applied
    110      * to the src space position to compute texture coordinates.
    111      */
    112     void addColorTextureProcessor(sk_sp<GrTextureProxy>, const SkMatrix&);
    113     void addColorTextureProcessor(sk_sp<GrTextureProxy>, const SkMatrix&, const GrSamplerState&);
    114 
    115     void addCoverageTextureProcessor(sk_sp<GrTextureProxy>, const SkMatrix&);
    116     void addCoverageTextureProcessor(sk_sp<GrTextureProxy>, const SkMatrix&, const GrSamplerState&);
    117 
    118     int numColorFragmentProcessors() const { return fColorFragmentProcessors.count(); }
    119     int numCoverageFragmentProcessors() const { return fCoverageFragmentProcessors.count(); }
    120     int numTotalFragmentProcessors() const { return this->numColorFragmentProcessors() +
    121                                               this->numCoverageFragmentProcessors(); }
    122 
    123     const GrXPFactory* getXPFactory() const { return fXPFactory; }
    124 
    125     GrFragmentProcessor* getColorFragmentProcessor(int i) const {
    126         return fColorFragmentProcessors[i].get();
    127     }
    128     GrFragmentProcessor* getCoverageFragmentProcessor(int i) const {
    129         return fCoverageFragmentProcessors[i].get();
    130     }
    131 
    132     /**
    133      * Returns true if the paint's output color will be constant after blending. If the result is
    134      * true, constantColor will be updated to contain the constant color. Note that we can conflate
    135      * coverage and color, so the actual values written to pixels with partial coverage may still
    136      * not seem constant, even if this function returns true.
    137      */
    138     bool isConstantBlendedColor(GrColor* constantColor) const;
    139 
    140     /**
    141      * A trivial paint is one that uses src-over and has no fragment processors.
    142      * It may have variable sRGB settings.
    143      **/
    144     bool isTrivial() const { return fTrivial; }
    145 
    146 private:
    147     // Since paint copying is expensive if there are fragment processors, we require going through
    148     // the Clone() method.
    149     GrPaint(const GrPaint&);
    150     GrPaint& operator=(const GrPaint&) = delete;
    151 
    152     friend class GrProcessorSet;
    153 
    154     const GrXPFactory* fXPFactory = nullptr;
    155     SkSTArray<4, std::unique_ptr<GrFragmentProcessor>> fColorFragmentProcessors;
    156     SkSTArray<2, std::unique_ptr<GrFragmentProcessor>> fCoverageFragmentProcessors;
    157     bool fDisableOutputConversionToSRGB = false;
    158     bool fAllowSRGBInputs = false;
    159     bool fTrivial = true;
    160     GrColor4f fColor = GrColor4f::OpaqueWhite();
    161 };
    162 
    163 #endif
    164