private void HandleTouches(MonoTouch.Foundation.NSSet touches, UIEvent evt)
{
var touch = (UITouch)evt.TouchesForView (this).AnyObject;
PointF pos;
pos = touch.LocationInView (this);
float w = Frame.Size.Width;
float h = Frame.Size.Height;
if (pos.X < 0)
saturation = 0;
else if (pos.X > w)
saturation = 1;
else
saturation = pos.X / w;
if (pos.Y < 0)
brightness = 1;
else if (pos.Y > h)
brightness = 0;
else
brightness = 1 - (pos.Y / h);
if (ColorPicked != null) {
ColorPicked ();
}
}