//创建多边形区域1  

  CRgn   poly1;  

  poly1.CreatePolygonRgn(lpVertex1,nVertexCount1,ALTERNATE);  

  delete[]   lpVertex1;  

  //创建多边形区域2  

  CRgn   poly2;  

  poly2.CreatePolygonRgn(lpVertex2,nVertexCount2,ALTERNATE);  

  delete[]   lpVertex2;  

   

  //获取相交的多边形区域  

  CRgn   IntersectRgn;  

  IntersectRgn.CreateRectRgn(0,0,0,0);  

  int   nIntersectResult   =   IntersectRgn.CombineRgn(   &poly1,&poly2,RGN_AND);  

  if(nIntersectResult==ERROR)  

        {  

        }  

    //没有相交  

    if(nIntersectResult==NULLREGION)  

            return   0;  

    /***********精华部分到了************/    

    //计算相交部分的面积  

      Region   intersectRegion((HRGN)IntersectRgn);  

      Matrix   matrix;  

      Rect*   rects   =   NULL;  

      int   count   =   0;    

   

      CClientDC   dc(this);  

      Graphics   graphics(   dc.GetSafeHdc()   );  

      graphics.GetTransform(&matrix);  

      count   =   intersectRegion.GetRegionScansCount(&matrix);  

      rects   =   (Rect*)malloc(count*sizeof(Rect));  

      intersectRegion.GetRegionScans(&matrix,   rects,   &count);  

       

      double   dbTotalArea=0;  

      for(int   j   =   0;   j   <   count;   ++j)  

          dbTotalArea +=(rects[j].GetBottom()-rects[j].GetTop())*   (rects[j].GetRight()-rects[j].GetLeft());  

   

      free(rects);  

      graphics.ReleaseHDC(dc.GetSafeHdc());  

      //返回面积值  

      return   dbTotalArea;