C# 中带有复选框的 TreeView

Question

我在 c# 中有一个带有复选框的树视图，我希望当用户检查一个节点时，自动检查以下级别上的所有节点。 有谁知道如何做到这一点，而无需在每次用户检查某个节点时在所有树上运行递归功能？

谢谢

//这个函数返回treeView。

   public TreeView GetTreeView()
    {

        getSubject();
        // fill the treeview with all subjects.
        foreach (Subject subject in subjects)
        {
            //for each root subject fill all the his children.
            if (subject.subjestId == subject.parentSubject)
            {
                TreeNode node = new TreeNode(subject.subjectString, subject.subjestId, subject.subjestId);
                addChild(node, subject.subjestId);
                tv.Nodes.Add(node);
            }
        }
        return tv;
    }
   // for each subject return sub subjects.
   private void addChild(TreeNode node, int parentId)
    {
        foreach (Subject subject in subjects)
        {
            if (subject.parentSubject == parentId && subject.parentSubject != subject.subjestId)
            {
                TreeNode childNode = new TreeNode(subject.subjectString, subject.subjestId, subject.subjestId);
                addChild(childNode, subject.subjestId);
                node.Nodes.Add(childNode);
            }
        }
    }

Answer 1

递归。像这样：

    bool busy = false;

    private void treeView1_AfterCheck(object sender, TreeViewEventArgs e) {
        if (busy) return;
        busy = true;
        try {
            checkNodes(e.Node, e.Node.Checked);
        }
        finally {
            busy = false;
        }
    }

    private void checkNodes(TreeNode node, bool check) {
        foreach (TreeNode child in node.Nodes) {
            child.Checked = check;
            checkNodes(child, check);
        }

Answer 2

private void treeView1_AfterCheck(object sender, TreeViewEventArgs e) {
  foreach (TreeNode child in e.Node.Nodes) {
    child.Checked = e.Node.Checked;
  }
}

Answer 3

这是一个更好的解决方案

private void trvMenuList_AfterCheck(object sender, TreeViewEventArgs e)
        {
            SetChildrenChecked(e.Node, e.Node.Checked);

        }

  private void SetChildrenChecked(TreeNode treeNode, bool checkedState)
        {
            foreach (TreeNode item in treeNode.Nodes)
            {
                if (item.Checked != checkedState)
                {
                    item.Checked = checkedState;
                }
                SetChildrenChecked(item, item.Checked);
            }
        }

Answer 4

正如许多答案所述，创建一个递归“将检查设置为子项”函数，然后在树上将其称为 AfterCheck。

不幸的是，即使您在代码中设置了检查值，框架也会回调 AfterCheck，尽管这在小树中可能不明显，但会为您的应用程序增加大量指数级的额外工作。为了避免这种情况，请过滤 AfterCheck 以仅在用户触发新函数时才触发该函数。

    private void tree_AfterCheck(object sender, TreeViewEventArgs e)
    {
        if (e.Action != TreeViewAction.Unknown)
        {
            SetChildrenChecked(e.Node);
        }
    }

    private void SetChildrenChecked(TreeNode treeNode)
    {
        foreach (TreeNode item in treeNode.Nodes)
        {
            if (item.Checked != treeNode.Checked)
            {
                item.Checked = treeNode.Checked;
            }

            if (item.Nodes.Count > 0)
            {
                SetChildrenChecked(item);
            }                
        }
    }

Answer 5

我对答案做了一些扩展；也通过更新父级。 [catch 中的 DisplayException 方法只是我经常使用的弹出窗口；你可以自己做]

    private bool _busy = false;  

    private void treeViewPassFail_AfterCheck(object sender, TreeViewEventArgs e)
    {
        try
        {
            if (_busy)
            {
                return;
            }

            _busy = true;

            CheckNodes(e.Node, e.Node.Checked);

            CheckParent(e.Node.Parent);
        }
        catch(Exception ex)
        {
            DisplayException(ex);
        }
        finally
        {
            _busy = false;
        }
    }

    private void CheckNodes(TreeNode node, bool check)
    {
        foreach(TreeNode child in node.Nodes)
        {
            child.Checked = check;
            CheckNodes(child, check);
        }
    }

    private void CheckParent(TreeNode parent)
    {
        if (parent != null)
        {
            bool allChecked = true;

            foreach (TreeNode node in parent.Nodes)
            {
                allChecked &= node.Checked;
            }

            parent.Checked = allChecked;
        }
    }

Answer 6

如果你想在 WinForms 中执行此操作，那么我认为你必须通过递归手动执行此操作 - 我不知道有什么更好的方法。