Can the default behavior of a Google Maps Event be overridden - google-maps

Question

I am trying create a restriction on the movement of an editable polygon. I want to prevent the inside path from being pulled outside of outer path. I am using Google Maps google.maps.geometry.poly.containsLocation function to check if the new point is within the outer bounds but I can't find a way to stop the action from happening if it is outside.
I have tried returning false but the polygon still goes to the new location
google.maps.event.addListener(poly.getPaths().getArray()[1], 'set_at', function() {
return keepInside(this, arguments[0], arguments[1]);
});
function keepInside(polygon, index, new_point)
{
outer_edge = new google.maps.Polygon({
paths: polygon.getArray(),
});
is_in = google.maps.geometry.poly.containsLocation(new_point,outer_edge);
if(!is_in)
{
return false;
}
return true;
}

Answer 1

You got pretty close with your original code. Instead of returning false, you could set the point back to it's original position. Also, the second argument passed to the set_at listener is not the new point but the old point. Try this:
google.maps.event.addListener(poly.getPaths().getArray()[1], 'set_at', function(index, oldPoint) {
return keepInside(this, index, this.getAt(index), oldPoint);
});
function keepInside(polygon, index, newPoint, oldPoint)
{
outer_edge = new google.maps.Polygon({
paths: polygon.getArray(),
});
if(!google.maps.geometry.poly.containsLocation(newPoint, outer_edge))
{
polygon.setAt(index, oldPoint);
}
}