在TreeView中使用CheckBox

实现C# TreeView的AfterCheck事件中的Checked，主要有以下情况：1.父节点勾选则子节点全部勾选2.父节点不勾选则子节点全部不勾选3.子节点全部不勾选则父节点不勾选4.子节点部分勾选则父节点不勾选5.子节点全部勾选则父节点被勾选以下是递归实现

private void SetNodeCheckStatus(TreeNode tn, bool chk){        if (tn == null)    return;    // Set child nodes check status    foreach( TreeNode tnChild in tn.Nodes)    {        tnChild.Checked = chk;        SetNodeCheckStatus(tnChild, chk);    }    // Set parent check status    int nNodeCount = 0;    TreeNode tnParent = tn;    while(tnParent.Parent != null)    {    nNodeCount = 0;    tnParent = tnParent.Parent;    foreach(TreeNode tnTmp in tnParent.Nodes)    {        if (tnTmp.Checked == chk)        {            nNodeCount++;        }    }    if (nNodeCount == tnParent.Nodes.Count)        tnParent.Checked = chk;    else        tnParent.Checked = false;    }}