public function area($exterior_only = FALSE, $signed = FALSE)
{
if ($this->isEmpty()) {
return 0;
}
if ($this->geos() && $exterior_only == FALSE) {
return $this->geos()->area();
}
$exterior_ring = $this->components[0];
$pts = $exterior_ring->getComponents();
$c = count($pts);
if ((int) $c == '0') {
return NULL;
}
$a = '0';
foreach ($pts as $k => $p) {
$j = ($k + 1) % $c;
$a = $a + $p->getX() * $pts[$j]->getY() - $p->getY() * $pts[$j]->getX();
}
if ($signed) {
$area = $a / 2;
} else {
$area = abs($a / 2);
}
if ($exterior_only == TRUE) {
return $area;
}
foreach ($this->components as $delta => $component) {
if ($delta != 0) {
$inner_poly = new Polygon(array($component));
$area -= $inner_poly->area();
}
}
return $area;
}
