TreeView Control Usage Guide

TreeView is a control used to display hierarchical data, commonly utilized for showcasing folder structures, directory layouts, and the like. It allows users to expand and collapse nodes, making it easy for them to navigate and manage hierarchical data structures.

The usage of TreeView is as follows:

1. Add a TreeView control: Add a TreeView control in the interface designer, and set its Name property to reference it in the code.
2. Add nodes: Use the TreeView.Nodes property to add nodes. Each node is a child node of the TreeView control, and you can use the Text property of the node to set the text displayed for the node.
3. // Add a root node
   TreeNode rootNode = new TreeNode(“Root Node”);
   treeView.Nodes.Add(rootNode);

   // Add child nodes
   TreeNode childNode1 = new TreeNode(“Child Node 1”);
   rootNode.Nodes.Add(childNode1);

   TreeNode childNode2 = new TreeNode(“Child Node 2”);
   rootNode.Nodes.Add(childNode2);

4. Node attributes can be set by using the ImageIndex and SelectedImageIndex properties of the node for setting icons, and using the Tag property for setting additional data.
5. // Assigning icon to the node
   childNode1.ImageIndex = 0;
   childNode1.SelectedImageIndex = 1;

   // Assigning additional data to the node
   childNode1.Tag = “Additional data for node1”;

6. Handling node events: You can subscribe to TreeView events to manage operations related to nodes, such as expanding and collapsing nodes.
7. // Event for node expansion
   treeView.NodeExpanded += new EventHandler(treeView_NodeExpanded);

   // Event for node collapse
   treeView.NodeCollapsed += new EventHandler(treeView_NodeCollapsed);

   // Handling node expansion event
   private void treeView_NodeExpanded(object sender, TreeNodeEventArgs e)
   {
   // Actions for when a node is expanded
   }

   // Handling node collapse event
   private void treeView_NodeCollapsed(object sender, TreeNodeEventArgs e)
   {
   // Actions for when a node is collapsed
   }

8. To set the checked state of a node, you can use the node’s Checked property to do so, and handle the node’s checking operation by subscribing to the TreeView’s AfterCheck event.
9. // Node selection event
   treeView.AfterCheck += new TreeViewEventHandler(treeView_AfterCheck);

   // Handling node selection event
   private void treeView_AfterCheck(object sender, TreeViewEventArgs e)
   {
   // Actions when a node is selected
   }

10. Other common operations: TreeView also provides some other commonly used operations, such as getting the currently selected node, expanding or collapsing all nodes, and more.
11. // Get the currently selected node
    TreeNode selectedNode = treeView.SelectedNode;

    // Expand all nodes
    treeView.ExpandAll();

    // Collapse all nodes

Here are some common usages of the TreeView control, which can be used to display and manipulate hierarchical data.