WinForm 简单实现仿WPF的WrapPanel和StackPanel

public interface IDesiredPanel
{
    Size GetDesiredSize(int availableWidth, int avaiableHeight);
}


public class StackPanel : Panel, IDesiredPanel
{


    protected override void OnLayout(LayoutEventArgs levent)
    {
        base.OnLayout(levent);

        List<Control> visibleCtrls = GetVisiableControls();

        int renderHeight = 0;
        for (int i = 0; i < visibleCtrls.Count; i++)
        {
            Control childCtrl = visibleCtrls[i];
            IDesiredPanel idesiredPnl = childCtrl as IDesiredPanel;
            Size childDesignSize = idesiredPnl == null
                   ? new Size(childCtrl.Width, childCtrl.Height)
                   : idesiredPnl.GetDesiredSize(this.Width, this.Height);

            childCtrl.Location = new Point(0, renderHeight);
            childCtrl.Width = childDesignSize.Width;
            renderHeight += childDesignSize.Height;
        }

        if (this.Parent is IDesiredPanel)
        {
            if (visibleCtrls.Count > 0)
            {
                this.Height = renderHeight;
            }
            else
            {
                this.Height = 3;
            }
        }
        else if (this.DesignMode == false)
        {
            this.Height = renderHeight;
        }
    }

    private List<Control> GetVisiableControls()
    {
        List<Control> controls = new List<Control>();
        foreach (Control c in this.Controls)
        {
            if (c.Visible)
            {
                controls.Add(c);
            }
        }
        controls.Reverse();
        return controls;
    }
    public Size GetDesiredSize(int availableWidth, int avaiableHeight)
    {
        List<Control> visibleCtrls = GetVisiableControls();
        int desiredHeight = 0;
        for (int i = 0; i < visibleCtrls.Count; i++)
        {
            Control childCtrl = visibleCtrls[i];
            IDesiredPanel idesiredPnl = childCtrl as IDesiredPanel;
            Size childDesiredSize = idesiredPnl == null
                   ? new Size(childCtrl.Width, childCtrl.Height)
                   : idesiredPnl.GetDesiredSize(availableWidth, avaiableHeight);

            desiredHeight += childDesiredSize.Height;
        }
        return new Size(availableWidth, desiredHeight);
    }

}

public class WrapPanel : Panel, IDesiredPanel
{
    protected override void OnLayout(LayoutEventArgs levent)
    {
        base.OnLayout(levent);

        List<Control> visibleCtrls = GetVisiableControls();


        int renderHeight = 0;
        int curLineWidth = 0, curLineMaxHeight = 0;
        for (int i = 0; i < visibleCtrls.Count; i++)
        {
            Control childCtrl = visibleCtrls[i];
            IDesiredPanel idesiredPnl = childCtrl as IDesiredPanel;
            Size childDesignSize = idesiredPnl == null
                   ? new Size(childCtrl.Width, childCtrl.Height)
                   : idesiredPnl.GetDesiredSize(this.Width, this.Height);

            childCtrl.Width = childDesignSize.Width;
            childCtrl.Height = childDesignSize.Height;
            if (curLineWidth == 0)
            {   //第一个元素
                curLineMaxHeight = Math.Max(curLineMaxHeight, childDesignSize.Height);
                childCtrl.Location = new Point(0, renderHeight);
                curLineWidth += childDesignSize.Width;                   
            }
            else if (curLineWidth + childDesignSize.Width < this.Width)
            {   //非第一个元素，再次元素则宽度累加 不会超出
                childCtrl.Location = new Point(curLineWidth, renderHeight);
                curLineWidth += childDesignSize.Width;
            }
            else
            {   //非第一个元素，再次元素则宽度累加 会超出，采用换行
                renderHeight += curLineMaxHeight;

                //换行了
                childCtrl.Location = new Point(0, renderHeight);
                curLineWidth = childCtrl.Width;
                curLineMaxHeight = childCtrl.Height;
            }


            if (curLineWidth > this.Width)
            {   //这个元素溢出了
                renderHeight += curLineMaxHeight;       //累加上
                curLineWidth = 0;       //重置为0
                curLineMaxHeight = 0;   //需要换到下一行
            }
        }
        if (curLineWidth > 0)
        {
            renderHeight += curLineMaxHeight;
        }

        if(this.Parent is IDesiredPanel)
        {
            if(visibleCtrls.Count>0)
            {
                this.Height =  renderHeight;
            }
            else
            {
                this.Height = 3;
            }
        }
        else if (this.DesignMode == false)
        {
            this.Height = renderHeight;
        }
    }
    private List<Control> GetVisiableControls()
    {
        List<Control> controls = new List<Control>();
        foreach (Control c in this.Controls)
        {
            if (c.Visible)
            {
                controls.Add(c);
            }
        }
        controls.Reverse();
        return controls;
    }

    public Size GetDesiredSize(int availableWidth,int avaiableHeight)
    {
        List<Control> visibleCtrls = GetVisiableControls();
        int desiredHeight = 0;
        int curLineWidth = 0,curLineMaxHeight = 0;
        for (int i = 0; i < visibleCtrls.Count; i++)
        {
            Control childCtrl = visibleCtrls[i];
            IDesiredPanel idesiredPnl = childCtrl as IDesiredPanel;
            Size childDesiredSize = idesiredPnl == null
                   ? new Size(childCtrl.Width, childCtrl.Height)
                   : idesiredPnl.GetDesiredSize(availableWidth,avaiableHeight);

            if (curLineWidth == 0)
            {
                curLineMaxHeight = Math.Max(curLineMaxHeight, childDesiredSize.Height);
                curLineWidth += childDesiredSize.Width;
            }
            else if (curLineWidth + childDesiredSize.Width < availableWidth)
            {
                curLineWidth += childDesiredSize.Width;
            }
            else
            {
                desiredHeight += curLineMaxHeight;

                curLineWidth = childCtrl.Width;
                curLineMaxHeight = childCtrl.Height;
            }
            if (curLineWidth > availableWidth)
            {
                desiredHeight += curLineMaxHeight;
                curLineWidth = 0;
                curLineMaxHeight = 0;
            }
        }
        if (curLineWidth > 0)
        {
            desiredHeight += curLineMaxHeight;
        }
        return new Size(availableWidth, desiredHeight);
    }
}