private void SetBindings()
{
if (_mask!=null)
{
Binding binding=new Binding();
binding.Path = new PropertyPath("Left");
binding.Source = this;
_mask.SetBinding(Canvas.LeftProperty, binding);
binding = new Binding();
binding.Path = new PropertyPath("Top");
binding.Source = this;
_mask.SetBinding(Canvas.TopProperty, binding);
binding = new Binding();
binding.Path = new PropertyPath("Width");
binding.Source = this;
_mask.SetBinding(WidthProperty, binding);
binding = new Binding();
binding.Path = new PropertyPath("Height");
binding.Source = this;
_mask.SetBinding(HeightProperty, binding);
}
}