public bool AddVertex2DChangeListener(Vertex2DChangeListener listener)
{
if (listener == null)
{
throw new System.ArgumentNullException();
}
if (listeners == null)
{
listeners = new List <Vertex2DChangeListener> (1);
listeners.Add(listener);
// listener.Vertex2DChangedEvent (this);//initial
return(true);
}
else
{
if (listeners.Contains(listener))
{
return(false);
}
else
{
listeners.Add(listener);
//listener.Vertex2DChangedEvent (this);//initial
return(true);
}
}
}
public bool RemoveVertex2DChangeListener(Vertex2DChangeListener listener) //TODO may be i should remove list when it is empty
{
if (listener != null)
{
return(listeners.Remove(listener));
}
return(false);
}
