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      1 /*
      2  * Copyright 2014 Google Inc.
      3  *
      4  * Use of this source code is governed by a BSD-style license that can be
      5  * found in the LICENSE file.
      6  */
      7 
      8 #ifndef GrProcessorAnalysis_DEFINED
      9 #define GrProcessorAnalysis_DEFINED
     10 
     11 #include "GrColor.h"
     12 
     13 class GrDrawOp;
     14 class GrFragmentProcessor;
     15 class GrPrimitiveProcessor;
     16 
     17 class GrProcessorAnalysisColor {
     18 public:
     19     enum class Opaque {
     20         kNo,
     21         kYes,
     22     };
     23 
     24     constexpr GrProcessorAnalysisColor(Opaque opaque = Opaque::kNo)
     25             : fFlags(opaque == Opaque::kYes ? kIsOpaque_Flag : 0), fColor(0) {}
     26 
     27     GrProcessorAnalysisColor(GrColor color) { this->setToConstant(color); }
     28 
     29     void setToConstant(GrColor color) {
     30         fColor = color;
     31         if (GrColorIsOpaque(color)) {
     32             fFlags = kColorIsKnown_Flag | kIsOpaque_Flag;
     33         } else {
     34             fFlags = kColorIsKnown_Flag;
     35         }
     36     }
     37 
     38     void setToUnknown() { fFlags = 0; }
     39 
     40     void setToUnknownOpaque() { fFlags = kIsOpaque_Flag; }
     41 
     42     bool isOpaque() const { return SkToBool(kIsOpaque_Flag & fFlags); }
     43 
     44     bool isConstant(GrColor* color = nullptr) const {
     45         if (kColorIsKnown_Flag & fFlags) {
     46             if (color) {
     47                 *color = fColor;
     48             }
     49             return true;
     50         }
     51         return false;
     52     }
     53 
     54     bool operator==(const GrProcessorAnalysisColor& that) const {
     55         if (fFlags != that.fFlags) {
     56             return false;
     57         }
     58         return (kColorIsKnown_Flag & fFlags) ? fColor == that.fColor : true;
     59     }
     60 
     61     /** The returned value reflects the common properties of the two inputs. */
     62     static GrProcessorAnalysisColor Combine(const GrProcessorAnalysisColor& a,
     63                                             const GrProcessorAnalysisColor& b) {
     64         GrProcessorAnalysisColor result;
     65         uint32_t commonFlags = a.fFlags & b.fFlags;
     66         if ((kColorIsKnown_Flag & commonFlags) && a.fColor == b.fColor) {
     67             result.fColor = a.fColor;
     68             result.fFlags = a.fFlags;
     69         } else if (kIsOpaque_Flag & commonFlags) {
     70             result.fFlags = kIsOpaque_Flag;
     71         }
     72         return result;
     73     }
     74 
     75 private:
     76     enum Flags {
     77         kColorIsKnown_Flag = 0x1,
     78         kIsOpaque_Flag = 0x2,
     79     };
     80     uint32_t fFlags;
     81     GrColor fColor;
     82 };
     83 
     84 enum class GrProcessorAnalysisCoverage { kNone, kSingleChannel, kLCD };
     85 
     86 /**
     87  * GrColorFragmentProcessorAnalysis gathers invariant data from a set of color fragment processor.
     88  * It is used to recognize optimizations that can simplify the generated shader or make blending
     89  * more effecient.
     90  */
     91 class GrColorFragmentProcessorAnalysis {
     92 public:
     93     GrColorFragmentProcessorAnalysis() = delete;
     94 
     95     GrColorFragmentProcessorAnalysis(const GrProcessorAnalysisColor& input,
     96                                      const GrFragmentProcessor* const* processors,
     97                                      int cnt);
     98 
     99     bool isOpaque() const { return fIsOpaque; }
    100 
    101     /**
    102      * Are all the fragment processors compatible with conflating coverage with color prior to the
    103      * the first fragment processor. This result assumes that processors that should be eliminated
    104      * as indicated by initialProcessorsToEliminate() are in fact eliminated.
    105      */
    106     bool allProcessorsCompatibleWithCoverageAsAlpha() const {
    107         return fCompatibleWithCoverageAsAlpha;
    108     }
    109 
    110     /**
    111      * Do any of the fragment processors require local coords. This result assumes that
    112      * processors that should be eliminated as indicated by initialProcessorsToEliminate() are in
    113      * fact eliminated.
    114      */
    115     bool usesLocalCoords() const { return fUsesLocalCoords; }
    116 
    117     /**
    118      * If we detected that the result after the first N processors is a known color then we
    119      * eliminate those N processors and replace the GrDrawOp's color input to the GrPipeline with
    120      * the known output of the Nth processor, so that the Nth+1 fragment processor (or the XP if
    121      * there are only N processors) sees its expected input. If this returns 0 then there are no
    122      * processors to eliminate.
    123      */
    124     int initialProcessorsToEliminate(GrColor* newPipelineInputColor) const {
    125         if (fProcessorsToEliminate > 0) {
    126             *newPipelineInputColor = fLastKnownOutputColor.toGrColor();
    127         }
    128         return fProcessorsToEliminate;
    129     }
    130 
    131     int initialProcessorsToEliminate(GrColor4f* newPipelineInputColor) const {
    132         if (fProcessorsToEliminate > 0) {
    133             *newPipelineInputColor = fLastKnownOutputColor;
    134         }
    135         return fProcessorsToEliminate;
    136     }
    137 
    138     /**
    139      * Provides known information about the last processor's output color.
    140      */
    141     GrProcessorAnalysisColor outputColor() const {
    142         if (fKnowOutputColor) {
    143             return fLastKnownOutputColor.toGrColor();
    144         }
    145         return fIsOpaque ? GrProcessorAnalysisColor::Opaque::kYes
    146                          : GrProcessorAnalysisColor::Opaque::kNo;
    147     }
    148 
    149 private:
    150     bool fIsOpaque;
    151     bool fCompatibleWithCoverageAsAlpha;
    152     bool fUsesLocalCoords;
    153     bool fKnowOutputColor;
    154     int fProcessorsToEliminate;
    155     GrColor4f fLastKnownOutputColor;
    156 };
    157 
    158 #endif
    159