class Shape

{

    private IDrawEngine engine;

    Shape()

    {

        this.engine = new DrawEngine();

    }

    public void Draw()

    {

        if (this is Circle)

        {

            var radius = (this as Circle).Radius;

            this.engine.DrawCircle(radius);

        }

        if (this is Rectangle)

        {

            var height = (this as Rectangle).Height;

            var width = (this as Rectangle).Width;

            this.engine.DrawRectangle(height, width);

        }

    }

}

class Circle : Shape

{

    public float Radius { get; set; }

}

class Rectangle : Shape

{

    public float Height { get; set; }

    public float Width { get; set; }

}