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      1 /*
      2  * Copyright 2011 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 #ifndef SkAntiEdge_DEFINED
      8 #define SkAntiEdge_DEFINED
      9 
     10 #include "SkFixed.h"
     11 #include "SkTDArray.h"
     12 
     13 struct SkBitmap;
     14 struct SkPoint;
     15 
     16 struct SkAntiEdge {
     17     SkAntiEdge* fNext; // list in walking order (y, then x, then diag)
     18     SkAntiEdge* fPrev; // reverse in walking order
     19     SkAntiEdge* fLink; // list in connected order, top to bottom
     20 
     21     SkFixed     fFirstX; // starting X
     22     SkFixed     fFirstY; // starting Y
     23     SkFixed     fLastX; // ending X
     24     SkFixed     fLastY; // ending Y
     25     SkFixed     fX0; // computed edge current value (may be off end)
     26     SkFixed     fY0;
     27     SkFixed     fX; // edge current value (always on edge)
     28     SkFixed     fY;
     29     SkFixed     fDX; // change in X per unit step in Y
     30     SkFixed     fDY; // change in Y per unit step in X
     31     SkFixed     fWalkX; // unit step position (integer after initial step)
     32     SkFixed     fWalkY;
     33     uint16_t    fPartialY; // initial partial coverage in Y (0 .. SkFixed1]
     34     int16_t     fWindingSum; // winding including contributions to the left
     35     int8_t      fWinding; // 1 or -1 (could be 2 bits)
     36     bool        fFinished : 1;
     37     unsigned    fDXFlipped : 1; // used as bool and to adjust calculations (0/1)
     38     bool        fLinkSet : 1; // set if edge has been attached to another edge
     39 
     40     void calcLine();
     41     bool setLine(const SkPoint& p0, const SkPoint& p1);
     42     uint16_t advanceX(SkFixed left);
     43     uint16_t advanceFlippedX(SkFixed left);
     44     void advanceY(SkFixed top);
     45 // FIXME: mark DEBUG
     46     void pointInLine(SkFixed x, SkFixed y);
     47     void pointOnLine(SkFixed x, SkFixed y);
     48     void validate();
     49 };
     50 
     51 class SkAntiEdgeBuilder {
     52 public:
     53 void process(const SkPoint* points, int ptCount,
     54         uint8_t* result, int pixelCol, int pixelRow);
     55 private:
     56     int build(const SkPoint pts[], int count);
     57     void calc();
     58     void link();
     59     void sort();
     60     void sort(SkTDArray<SkAntiEdge*>&);
     61     void split();
     62     void split(SkAntiEdge* edge, SkFixed y);
     63     void walk(uint8_t* result, int rowBytes, int height);
     64     SkAntiEdge fHeadEdge;
     65     SkAntiEdge fTailEdge;
     66     SkTDArray<SkAntiEdge> fEdges;
     67     SkTDArray<SkAntiEdge*> fList;
     68 };
     69 
     70 void SkAntiEdge_Test();
     71 void CreateSweep(SkBitmap* , float width);
     72 void CreateHorz(SkBitmap* );
     73 void CreateVert(SkBitmap* );
     74 void CreateAngle(SkBitmap* sweep, float angle);
     75 
     76 #endif
     77