Function msGetPolygonCentroid

mapprimitive.c:1247–1272

}

int msGetPolygonCentroid(shapeObj *p, pointObj *lp, double *miny, double *maxy)
{
  int i,j;
  double cent_weight_x=0.0, cent_weight_y=0.0;
  double len, total_len=0;

  *miny = *maxy = p->line[0].point[0].y;
  for(i=0; i<p->numlines; i++) {
    for(j=1; j<p->line[i].numpoints; j++) {
      *miny = MS_MIN(*miny, p->line[i].point[j].y);
      *maxy = MS_MAX(*maxy, p->line[i].point[j].y);
      len = msDistancePointToPoint(&(p->line[i].point[j-1]), &(p->line[i].point[j]));
      cent_weight_x += len * ((p->line[i].point[j-1].x + p->line[i].point[j].x)/2);
      cent_weight_y += len * ((p->line[i].point[j-1].y + p->line[i].point[j].y)/2);
      total_len += len;
    }
  }

  if(total_len == 0)
    return(MS_FAILURE);

  lp->x = cent_weight_x / total_len;
  lp->y = cent_weight_y / total_len;
  
  return(MS_SUCCESS);
}

/*
** Find a label point in a polygon.