如何对齐SpriteBatch.DrawString绘制的文本？

有没有一种简单的方法可以将文本向右和居中对齐（而不是默认的左对齐）？

我使用这段代码：

 [Flags]
 public enum Alignment { Center=0, Left=1, Right=2, Top=4, Bottom = 8 }

 public void DrawString(SpriteFont font, string text, Rectangle bounds, Alignment align, Color color )
    {
        Vector2 size = font.MeasureString( text );
        Vector2 pos = bounds.GetCenter( );
        Vector2 origin = size*0.5f;

        if ( align.HasFlag( Alignment.Left ) )
            origin.X += bounds.Width/2 - size.X/2;

        if ( align.HasFlag( Alignment.Right ) )
            origin.X -= bounds.Width/2 - size.X/2;

        if ( align.HasFlag( Alignment.Top ) )
            origin.Y += bounds.Height/2 - size.Y/2;

        if ( align.HasFlag( Alignment.Bottom ) )
            origin.Y -= bounds.Height/2 - size.Y/2;

        DrawString( font, text, pos, color, 0, origin, 1, SpriteEffects.None, 0 );
    }