我如何使画布在一个事件可见

我有以下问题，我想通过一个按钮点击生成一个小画布，生成后我想通过一个键按事件移动它，但我不能在事件中看到画布。我怎样才能使它可见?(WPF的源代码中没有XAML)

public void Button_Click_1(object sender, RoutedEventArgs e)
{   
    Canvas c = new Canvas();
    c.Height = System.Windows.SystemParameters.PrimaryScreenHeight;
    c.Width = System.Windows.SystemParameters.PrimaryScreenWidth;
    c.Loaded += c_Loaded;
    Grid.Children.Add(c);
    Canvas ship = new Canvas();
    ship.Background = Brushes.Aquamarine;
    ship.Height = 30;
    ship.Width = 30;
    ship.KeyDown += ship_KeyDown;
    Canvas.SetTop(ship, 50);
    c.Children.Add(ship);  
}
void ship_KeyDown(object sender, KeyEventArgs e)
{
    canvas.Setleft(ship, canvas.Getleft(ship) +10);  //here i can not see the object "ship" :(          
}

Canvas ship = (Canvas) sender;