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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 GrProcOptInfo_DEFINED
      9 #define GrProcOptInfo_DEFINED
     10 
     11 #include "GrColor.h"
     12 #include "GrInvariantOutput.h"
     13 
     14 class GrDrawBatch;
     15 class GrFragmentProcessor;
     16 class GrPrimitiveProcessor;
     17 class GrProcessor;
     18 
     19 /**
     20  * GrProcOptInfo gathers invariant data from a set of processor stages.It is used to recognize
     21  * optimizations related to eliminating stages and vertex attributes that aren't necessary for a
     22  * draw.
     23  */
     24 class GrProcOptInfo {
     25 public:
     26     GrProcOptInfo()
     27         : fInOut(0, static_cast<GrColorComponentFlags>(0), false)
     28         , fFirstEffectiveProcessorIndex(0)
     29         , fInputColorIsUsed(true)
     30         , fInputColor(0)
     31         , fReadsFragPosition(false) {}
     32 
     33     void calcWithInitialValues(const GrFragmentProcessor* const *, int cnt, GrColor startColor,
     34                                GrColorComponentFlags, bool areCoverageStages, bool isLCD = false);
     35     void initUsingInvariantOutput(GrInitInvariantOutput invOutput);
     36     void completeCalculations(const GrFragmentProcessor * const processors[], int cnt);
     37 
     38     bool isSolidWhite() const { return fInOut.isSolidWhite(); }
     39     bool isOpaque() const { return fInOut.isOpaque(); }
     40     bool isSingleComponent() const { return fInOut.isSingleComponent(); }
     41     bool allStagesMultiplyInput() const { return fInOut.allStagesMulInput(); }
     42 
     43     // TODO: Once texture pixel configs quaries are updated, we no longer need this function.
     44     // For now this function will correctly tell us if we are using LCD text or not and should only
     45     // be called when looking at the coverage output.
     46     bool isFourChannelOutput() const { return !fInOut.isSingleComponent() &&
     47                                                fInOut.isLCDCoverage(); }
     48 
     49     GrColor color() const { return fInOut.color(); }
     50 
     51     GrColorComponentFlags validFlags() const {
     52         return fInOut.validFlags();
     53     }
     54 
     55     /**
     56      * Returns the index of the first effective color processor. If an intermediate processor
     57      * doesn't read its input or has a known output, then we can ignore all earlier processors
     58      * since they will not affect the final output. Thus the first effective processors index is
     59      * the index to the first processor that will have an effect on the final output.
     60      *
     61      * If processors before the firstEffectiveProcessorIndex() are removed, corresponding values
     62      * from inputColorIsUsed(), inputColorToEffectiveProcessor(), removeVertexAttribs(), and
     63      * readsDst() must be used when setting up the draw to ensure correct drawing.
     64      */
     65     int firstEffectiveProcessorIndex() const { return fFirstEffectiveProcessorIndex; }
     66 
     67     /**
     68      * True if the first effective processor reads its input, false otherwise.
     69      */
     70     bool inputColorIsUsed() const { return fInputColorIsUsed; }
     71 
     72     /**
     73      * If input color is used and per-vertex colors are not used, this is the input color to the
     74      * first effective processor.
     75      */
     76     GrColor inputColorToFirstEffectiveProccesor() const { return fInputColor; }
     77 
     78     /**
     79      * Returns true if any of the processor preserved by GrProcOptInfo read the frag position.
     80      */
     81     bool readsFragPosition() const { return fReadsFragPosition; }
     82 
     83 private:
     84     void internalCalc(const GrFragmentProcessor* const[], int cnt, bool initWillReadFragPosition);
     85 
     86     GrInvariantOutput fInOut;
     87     int fFirstEffectiveProcessorIndex;
     88     bool fInputColorIsUsed;
     89     GrColor fInputColor;
     90     bool fReadsFragPosition;
     91 };
     92 
     93 #endif
     94