Question

I have treeview in windowsform application when searching for node is performed I need to hide all the remaining node and I need to show only the searched node and its parent .like

grandParent
Parent1
child1
child2
child3.
parent2
child4
child5
if the searched node is child 3 i need to show the out put as..

grandParent
Parent1
child3
all auother are to be Hide.

Answer 1

Unfortunately (as far as I know) if you are using a WinForms TreeView control then hiding nodes is not as simple as setting the IsVisible property (due to the fact that the property is read only).

The only way of hiding nodes is to remove them from the Nodes collection.

This means displaying them again would require you to keep track of their location within the tree hierarchy to be able to restore them.

The following code seems to do what you require:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using ClassLibrary;
using System.Xml;
using System.Diagnostics;
using System.IO;
using System.Xml.Linq;

namespace WindowsFormsApplication
{
    public partial class HideRestoreNodesForm : Form
    {
        private List<RemovedTreeNode> _removedNodes = new List<RemovedTreeNode>();

        public HideRestoreNodesForm()
        {
            InitializeComponent();

            //AddNodesToTree();
        }

        private void searchButton_Click(object sender, EventArgs e)
        {
            TreeNode[] foundNodes = treeView1.Nodes.Find("NameOfNodeToFind", true);
            if(foundNodes.Length > 0)
            {
                TreeNode foundNode = foundNodes[0];
                HideNodes(treeView1.Nodes, foundNode);
            }
        }

        private void HideNodes(TreeNodeCollection nodes, TreeNode visibleNode)
        {
            List<TreeNode> nodesToRemove = new List<TreeNode>();
            foreach (TreeNode node in nodes)
            {
                if (!AreNodesRelated(node, visibleNode))
                {
                    _removedNodes.Add(new RemovedTreeNode() { RemovedNode = node, ParentNode = node.Parent, RemovedNodeIndex = node.Index });
                    nodesToRemove.Add(node);
                }
                else
                {
                    HideNodes(node.Nodes, visibleNode);
                }
            }

            foreach (TreeNode node in nodesToRemove)
                node.Remove();
        }

        private bool AreNodesRelated(TreeNode firstNode, TreeNode secondNode)
        {
            if (!IsNodeAncestor(firstNode, secondNode) && !IsNodeAncestor(secondNode, firstNode) && firstNode != secondNode)
            {
                return false;
            }
            else
            {
                return true;
            }
        }

        private bool IsNodeAncestor(TreeNode nodeToCheck, TreeNode descendantNode)
        {
            TreeNode parentNode = descendantNode.Parent;
            while (parentNode != null)
            {
                if (parentNode == nodeToCheck)
                {
                    return true;
                }
                else
                {
                    parentNode = parentNode.Parent;
                }
            }

            return false;
        }

        private void restoreNodes_Click(object sender, EventArgs e)
        {
            RestoreNodes();
        }

        private void RestoreNodes()
        {
            _removedNodes.Reverse();
            foreach (RemovedTreeNode removedNode in _removedNodes)
            {
                if (removedNode.ParentNode == null)
                    treeView1.Nodes.Add(removedNode.RemovedNode);
                else
                    removedNode.ParentNode.Nodes.Insert(removedNode.RemovedNodeIndex ,removedNode.RemovedNode);
            }

            _removedNodes.Clear();
        }
    }

    public class RemovedTreeNode
    {
        public TreeNode RemovedNode { get; set; }
        public int RemovedNodeIndex { get; set; }
        public TreeNode ParentNode { get; set; }
    }
}

Hope this helps you.

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