public class Diagnol:Panel

    {

        /// <summary>

        /// 测量

        /// </summary>

        /// <param name="availableSize">This的尺寸</param>

        /// <returns></returns>

        protected override Size MeasureOverride(Size availableSize)

        {

            Size size = new Size();

            foreach (UIElement item in this.InternalChildren)

            {

                item.Measure(availableSize);

                size.Width += item.DesiredSize.Width;

                size.Height += item.DesiredSize.Height;

            }

            //返回所有子控件需要的 总尺寸

            return base.MeasureOverride(size);

        }

        /// <summary>

        /// 排列每个子控件

        /// </summary>

        /// <param name="finalSize">This的尺寸</param>

        /// <returns></returns>

        protected override Size ArrangeOverride(Size finalSize)

        {

            Point point1 = new Point();

            //子控件个数

            int count = this.InternalChildren.Count;

            //总个数的中间值

            int index = (count + ) / -;

            for (int i = ; i < this.InternalChildren.Count; i++)

            {

                var child = this.InternalChildren[i];

                //如果就一个没法玩，直接排列

                if (count <= )

                {

                    //设置子控件的位置

                    child.Arrange(new Rect(point1, child.DesiredSize));

                    break;

                }

                //玩起来

                if (i < index)

                {

                    child.Arrange(new Rect(point1, child.DesiredSize));

                    point1.X += child.DesiredSize.Width;

                    point1.Y += child.DesiredSize.Height;

                }

                else

                {

                    child.Arrange(new Rect(point1, child.DesiredSize));

                    point1.X += child.DesiredSize.Width;

                    point1.Y -= child.DesiredSize.Height;

                }

            }

            return base.ArrangeOverride(finalSize);

        }

    }

 <local:Diagnol>

            <Button BorderBrush="Black" Background="Red" Content="0" Width="40"></Button>

            <Button BorderBrush="Black" Background="Red" Content="1" Width="40"></Button>

            <Button BorderBrush="Black" Background="Red" Content="2" Width="40"></Button>

            <Button BorderBrush="Black" Background="Red" Content="3" Width="40"></Button>

            <Button BorderBrush="Black" Background="Red" Content="4" Width="40"></Button>

            <Button BorderBrush="Black" Background="Red" Content="5" Width="40"></Button>

            <Button BorderBrush="Black" Background="Red" Content="6" Width="40"></Button>

            <Button BorderBrush="Black" Background="Red" Content="7" Width="40"></Button>

            <Button BorderBrush="Black" Background="Red" Content="8" Width="40"></Button>

        </local:Diagnol>