Function msPolygonLabelPoint

mapprimitive.c:1277–1506

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

** Find a label point in a polygon.
*/
int msPolygonLabelPoint(shapeObj *p, pointObj *lp, double min_dimension)
{
  double slope;
  pointObj *point1=NULL, *point2=NULL, cp;
  int i, j, nfound;
  double x, y, *intersect, temp;
  double min, max;
  int wrong_order, n;
  double len, max_len=0;
  double minx, maxx, maxy, miny;

  int method = 2;

  msComputeBounds(p);
  minx = p->bounds.minx;
  miny = p->bounds.miny;
  maxx = p->bounds.maxx;
  maxy = p->bounds.maxy;

  if(min_dimension != -1)
    if(MS_MIN(maxx-minx,maxy-miny) < min_dimension) return(MS_FAILURE);

  cp.x = (maxx+minx)/2.0;
  cp.y = (maxy+miny)/2.0;

  switch (method) {
  case 0: /* MBR */
    lp->x = cp.x;
    lp->y = cp.y;
    break;
  case 1: /* centroid */
    if(msGetPolygonCentroid(p, lp, &miny, &maxy) != MS_SUCCESS) return(MS_FAILURE);  
    break;
  case 2: /* center of gravity */
    if(getPolygonCenterOfGravity(p, lp) != MS_SUCCESS) return(MS_FAILURE);
    break;
  }

  if(msIntersectPointPolygon(lp, p) == MS_TRUE) {
    double dist, min_dist=-1;

    /* compute a distance to the polygon */
    for(j=0;j<p->numlines;j++) {
      for(i=1; i<p->line[j].numpoints; i++) {
        dist = msSquareDistancePointToSegment(lp, &(p->line[j].point[i-1]), &(p->line[j].point[i]));
        if((dist < min_dist) || (min_dist < 0)) min_dist = dist;
      }
    }
    min_dist = sqrt(min_dist);

    if(min_dist > .1*MS_MAX(maxx-minx, maxy-miny))
      return(MS_SUCCESS); /* point is not too close to the edge */
  }

  // printf("label: %s\n", p->text);
  // printf("    bbox: %g %g %g %g\n",minx, miny, maxx, maxy);
  // printf("    center: %g %g\n", cp.x, cp.y);
  // printf("    center of gravity: %g %g\n", lp->x, lp->y);