How to traverse and find the specified CheckBox status in the Windows Form Control TreeView

As a common Control, the TreeView Control gives us a lot of capabilities to present hierarchical data sources. Its powerful customization and ease of use are very popular with client application developers. However, when displaying the status of the CheckBox control in front of the tree control, we sometimes need to traverse the entire tree to get the setting status of all checkpoints.

Before using the sample code, we will first demonstrate the relevant types:

1. TreeView class

Public classTreeView: Control {

// Set the events triggered between and before the CheckBox is selected in the tree

       public event TreeViewEventHandler AfterCheck;

       public event TreeViewCancelEventHandler BeforeCheck;

// Set the CheckBoxes enabling status, code-level use

       public bool CheckBoxes { get; set; }

// Obtain the parent node at the highest level of the current child node

       public TreeNode TopNode { get; set; }

}

2. TreeNode class:

 public class TreeNode : MarshalByRefObject, ICloneable, ISerializable{

// CheckBox status of the current node

   public bool Checked { get; set; }

// Additional special information

   public object Tag { get; set; }

// Traverse the attributes of the node linked list

  public TreeNode PrevNode { get; }

  public TreeNode FirstNode { get; }

  public TreeNode NextNode { get; }

}

Now we can operate the CheckBox in the TreeView through the relevant attributes and methods provided by the above two classes.

Intent:

We need to obtain information about all the selected checkboxes. For convenience, Tag is used in the TreeView node to append the CheckBox ID information.

Key steps:

1,Add an AfterCheck event to set the CheckBox status of the TreeNode

If you select the CheckBox, set the TreeNode Tag to "True". Otherwise, set it to null. The Code is as follows:

 Private void nodeTree_AfterCheck (object sender, TreeViewEventArgs e ){
TreeNode node = e. Node;

If (node. Tag = null)
Node. Tag = tag; // additional node Information
Else

Node. Tag = null;

}

2,Search for the root node of the TreeView

Because the TopNode attribute of the TreeView can obtain the top-level node of the selected node, we can use it to traverse forward and get the root node. The Code is as follows:

 TreeNode node = nodeTree. TopNode; // obtain the root node of the TreeView. Note that there is only one root node.

// Each time the root node is searched

While (node. PrevNode! = Null)

Node = node. PrevNode;

 

3,Traverse all Tree nodes to get the corresponding status

For the convenience of the example, we didn't use the method of getting data from the database, but we used the built-in XML data source, and we presented the result to the user in the form of MessageBox to display the status. [The Tree recursion algorithm is used here] the relevant code is as follows:

Traversal method

 Private void TraversNodes (TreeNode parent ){

TreeNode node = parent;

If (node! = Null ){

If (node. Tag! = Null & node. Tag. ToString () = tag)

NodesTag. AppendFormat ("node: {0} has checked \ n", node. Name );

// Recursively traverse the tree

If (node. FirstNode! = Null ){

TraversNodes (node. FirstNode );

}

If (node. NextNode! = Null ){

TraversNodes (node. NextNode );

}

}

}

Result

 

Tip:

Here is just a relatively simple example of the traversal algorithm of the built-in control in TreeView. Because no relevant information is found on the Internet, it is written to a friend who needs it for reference. Sample Code