polygon

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// Copyright (C) 2010, Guy Barrand. All rights reserved.
// See the file tools.license for terms.
 
#ifndef tools_zb_polygon
#define tools_zb_polygon
 
#include "edge_table"
#include "../mnmx"
 
namespace tools {
namespace zb {
 
class polygon {
 
  static const int NUMPTSTOBUFFER = 200;
 
  typedef struct _POINTBLOCK {
      point pts[NUMPTSTOBUFFER];
      struct _POINTBLOCK* next;
  } POINTBLOCK;
 
  int             m_pETEn;
  EdgeTableEntry* m_pETEs;
  int             m_numAllocPtBlocks;
  POINTBLOCK      m_FirstPtBlock;
public:
  polygon():m_pETEn(0),m_pETEs(NULL),m_numAllocPtBlocks(0){}
  virtual ~polygon(){clear();}
protected:
  polygon(const polygon&){}
  polygon& operator=(const polygon&){return *this;}
public:
  void clear(){
    POINTBLOCK* curPtBlock;
    cmem_free(m_pETEs);
    m_pETEn = 0;
    for(curPtBlock = m_FirstPtBlock.next; --m_numAllocPtBlocks >= 0;){
        POINTBLOCK* tmpPtBlock;
        tmpPtBlock  = curPtBlock->next;
        cmem_free(curPtBlock);
        curPtBlock  = tmpPtBlock;
    }
    m_numAllocPtBlocks = 0;
  }
 
  typedef void (*scan_func)(void*,int,int,int);
 
  void scan(int    Count,         /* number of pts  */
            const point* Pts,     /* the pts        */
            int    rule,          /* winding rule   */
            scan_func a_proc,void* a_tag){
    // polytoregion
    //   Scan converts a polygon by returning a run-length
    //   encoding of the resultant bitmap -- the run-length
    //   encoding is in the form of an array of rectangles.
 
    EdgeTableEntry* pAET;   /* Active Edge Table       */
    int y;                  /* current scanline        */
    int iPts = 0;           /* number of pts in buffer */
    EdgeTableEntry* pWETE;  /* Winding Edge Table Entry*/
    ScanLineList*   pSLL;   /* current scanLineList    */
 
    EdgeTableEntry* pPrevAET;        /* ptr to previous AET     */
    EdgeTable ET;                    /* header node for ET      */
    EdgeTableEntry AET;              /* header node for AET     */
    ScanLineListBlock SLLBlock;      /* header for scanlinelist */
    int         fixWAET = 0;
    POINTBLOCK* curPtBlock;
    int         numFullPtBlocks = 0;
 
    if(a_proc==NULL) return;
    if(Count==0)  return;
 
    /* special case a rectangle */
    point* pts = (point*)Pts;
    if (((Count == 4) ||
     ((Count == 5) && (pts[4].x == pts[0].x) && (pts[4].y == pts[0].y))) &&
    (((pts[0].y == pts[1].y) &&
      (pts[1].x == pts[2].x) &&
      (pts[2].y == pts[3].y) &&
      (pts[3].x == pts[0].x)) ||
     ((pts[0].x == pts[1].x) &&
      (pts[1].y == pts[2].y) &&
      (pts[2].x == pts[3].x) &&
      (pts[3].y == pts[0].y))))
      {
        int  xmin,xmax,ymin,ymax;
    xmin = (int)mn(pts[0].x, pts[2].x);
    ymin = (int)mn(pts[0].y, pts[2].y);
    xmax = (int)mx(pts[0].x, pts[2].x);
    ymax = (int)mx(pts[0].y, pts[2].y);
    if ((xmin != xmax) && (ymin != ymax))
        {
              for(y=ymin;y<=ymax;y++)  a_proc(a_tag,xmin  ,xmax  ,y);
        }
    return;
    }
 
    if(Count>m_pETEn)
      {
    cmem_free(m_pETEs);
    m_pETEn = Count;
    m_pETEs = cmem_alloc<EdgeTableEntry>(m_pETEn);
    if(m_pETEs==NULL)
      {
        m_pETEn = 0;
        return;
      }
      }
 
    CreateETandAET (Count,(point*)Pts, &ET, &AET, m_pETEs, &SLLBlock);
 
    pSLL           = ET.scanlines.next;
 
    curPtBlock     = &m_FirstPtBlock;
    pts            =  m_FirstPtBlock.pts;
 
 
    if (rule==0)
      {
        /*
         *  for each scanline
         */
        for (y = ET.ymin; y < ET.ymax; y++) {
            /*
             *  Add a new edge to the active edge table when we
             *  get to the next edge.
             */
            if (pSLL != NULL && y == pSLL->scanline)
          {
                LoadAET(&AET, pSLL->edgelist);
                pSLL = pSLL->next;
          }
            pPrevAET = &AET;
            pAET = AET.next;
 
            /*
             *  for each active edge
             */
            while (pAET) {
                pts->x = pAET->bres.minor_axis;
                pts->y = y;
                pts++;
                iPts++;
 
                /*
                 *  send out the buffer
                 */
                if (iPts == NUMPTSTOBUFFER)
          {
                    if(numFullPtBlocks < m_numAllocPtBlocks)
                      {
                        curPtBlock = curPtBlock->next;
                      }
            else
              {
            POINTBLOCK* tmpPtBlock = cmem_alloc<POINTBLOCK>(1);
                        if(tmpPtBlock==NULL)
              {
                FreeStorage(SLLBlock.next);
                return;
              }
            tmpPtBlock->next = NULL; /*Barrand*/
            curPtBlock->next = tmpPtBlock;
            curPtBlock       = tmpPtBlock;
            m_numAllocPtBlocks++;
              }
            numFullPtBlocks++;
            pts  = curPtBlock->pts;
                    iPts = 0;
          }
 
                EVALUATEEDGEEVENODD(pAET, pPrevAET, y)
            }
            (void) InsertAndSort(&AET);
        }
      }
    else
      {
        /*
         *  for each scanline
         */
        for (y = ET.ymin; y < ET.ymax; y++) {
            /*
             *  Add a new edge to the active edge table when we
             *  get to the next edge.
             */
            if (pSLL != NULL && y == pSLL->scanline)
          {
                LoadAET(&AET, pSLL->edgelist);
                ComputeWAET(&AET);
                pSLL = pSLL->next;
          }
            pPrevAET = &AET;
            pAET = AET.next;
            pWETE = pAET;
 
            /*
             *  for each active edge
             */
            while (pAET) {
                /*
                 *  add to the buffer only those edges that
                 *  are in the Winding active edge table.
                 */
                if (pWETE == pAET) {
                    pts->x = pAET->bres.minor_axis;
                    pts->y = y;
                    pts++;
            iPts++;
 
                    /*
                     *  send out the buffer
                     */
            if (iPts == NUMPTSTOBUFFER)
              {
            if(numFullPtBlocks < m_numAllocPtBlocks)
              {
                curPtBlock = curPtBlock->next;
              }
            else
              {
                POINTBLOCK* tmpPtBlock = cmem_alloc<POINTBLOCK>(1);
                            if(tmpPtBlock==NULL)
                  {
                FreeStorage(SLLBlock.next);
                return;
                  }
                tmpPtBlock->next = NULL; /*Barrand*/
                curPtBlock->next = tmpPtBlock;
                curPtBlock       = tmpPtBlock;
                m_numAllocPtBlocks++;
              }
            numFullPtBlocks++;
            pts  = curPtBlock->pts;
            iPts = 0;
              }
                    pWETE = pWETE->nextWETE;
                }
                EVALUATEEDGEWINDING(pAET, pPrevAET, y, fixWAET)
            }
 
            /*
             *  recompute the winding active edge table if
             *  we just resorted or have exited an edge.
             */
            if ( (InsertAndSort(&AET)!=0) || (fixWAET!=0) )
          {
                ComputeWAET(&AET);
                fixWAET = 0;
          }
        }
      }
    FreeStorage   (SLLBlock.next);
 
    ScanPoints (numFullPtBlocks, iPts, &m_FirstPtBlock,a_proc,a_tag);
 
  }
protected:
  void ScanPoints (int  numFullPtBlocks,
                   int  iCurPtBlock,
                   POINTBLOCK* FirstPtBlock,
                   scan_func a_proc,void* a_tag) {
    point*  pts;
    POINTBLOCK* CurPtBlock;
    int         i;
    CurPtBlock = FirstPtBlock;
    for ( ; numFullPtBlocks >= 0; numFullPtBlocks--)
      {
        /* the loop uses 2 points per iteration */
        i = numFullPtBlocks!=0 ? NUMPTSTOBUFFER >> 1 : iCurPtBlock >> 1 ;
        for (pts = CurPtBlock->pts; i--; pts += 2)
    {
      a_proc (a_tag,(int)(pts->x),(int)pts[1].x,(int)pts->y);
    }
        CurPtBlock = CurPtBlock->next;
      }
  }
 
 
};
 
}}
 
#endif