Function getRingArea

mapprimitive.c:1186–1195

}

static double getRingArea(lineObj *ring)
{
  int i;
  double s=0;

  for(i=0; i<ring->numpoints-1; i++)
    s += (ring->point[i].x*ring->point[i+1].y - ring->point[i+1].x*ring->point[i].y);

  return (MS_ABS(s/2));
}

double msGetPolygonArea(shapeObj *p) 
{