如何从C＃中分配的图像列表中为TreeView中的父节点和子节点分配图像？

Question

I have a TreeView and an associated ImageList. What are the steps to add images to the Parent and child nodes ?

All the nodes are being added from the code. Nothing is done from the Design.

public void fill_tree()
        {
            host_listbox_new.Items.Clear();
            foreach (KeyValuePair<string, host_config> hlitem in host_list)
            {
                string sitem = hlitem.Key;
                if (host_list[sitem].sessionOptions == null)
                    host_list[sitem].sessionOptions = new SessionOptions();
                host_list[sitem].sessionOptions.Protocol = Protocol.Sftp;
                host_list[sitem].sessionOptions.HostName = host_list[sitem].ip;
                host_list[sitem].sessionOptions.UserName = host_list[sitem].username;
                host_list[sitem].sessionOptions.Password = host_list[sitem].password;
                host_list[sitem].sessionOptions.PortNumber = Convert.ToInt32(host_list[sitem].port);
                //host_list[sitem].sessionOptions.SshHostKeyFingerprint = host_list[sitem].rsa;

                if (treeView1.SelectedNode != null)
                {
                    treeView1.SelectedNode.Nodes.Add(hlitem.Key.ToString());

                }
                else 
                {
                    treeView1.Nodes[0].Nodes.Add(hlitem.Key.ToString());
                }



            }
        }

private void Parent_Load(object sender, EventArgs e)
        {
            read_process_config();
            read_host_config();
            host_listbox.Items.Clear();
            treeView1.BeginUpdate();
            treeView1.Nodes.Add("Servers");
            fill_tree();
            treeView1.EndUpdate();
            treeView1.ExpandAll();
            connect_server_bttn.Enabled = false;

        }

i want to add items ie child nodes to Server Parent node each of them having one image before them ( green image if hlitem.Value.connected is true . red image if hlitem.Value.connected is false )

But i have no idea about treeview or imagelist. Can anyone help me about the whole thing?

Answer 1

The Add command returns a reference to the new Node. You can use it to style the Node. Change your code to this:

if (treeView1.SelectedNode != null)
{
    TreeNode tn =treeView1.SelectedNode.Nodes.Add(hlitem.Key.ToString());
    tn.ImageIndex = yourIndex;

}
else 
{
    TreeNode tn =treeView1.Nodes[0].Nodes.Add(hlitem.Key.ToString());
    tn.ImageIndex = yourIndex;
}

Or whatever logic you need to set the index.

If you need the parent node's index you could write:

tn.ImageIndex = tn.Parent.ImageIndex;

You may also want ot check out the other formats of the Add method. Some let you include the ImageIndex directly. You can also include the SelectedIndex; especially if you don't want that you should include it to prevent the Tree using its default SelectedIndex!

This will set the node to show the 2nd image, whether selected or not:

TreeNode tn =treeView1.Nodes[0].Nodes.Add(sitem, sitem, 1,1 );

Since you can't set a property of an object before you have created it, you can't set the Child nodes when you create the parent node. Instead you can use a simple function to do the changes:

void copyImgIndexToChildren(TreeNode tn)
{
    if (tn.Nodes.Count > 0) 
        foreach (TreeNode cn in tn.Nodes) cn.ImageIndex = tn.ImageIndex;
}

void copyImgIndexToAllChildren(TreeNode tn)
{
    if (tn.Nodes.Count > 0)
        foreach (TreeNode cn in tn.Nodes)
        {
            cn.ImageIndex = tn.ImageIndex;
            copyImgIndexToAllChildren(cn);
        }
}

The first method changes the direct ChildNodes only , the 2nd recursively changes all levels below the starting node.

BTW: Is there a reason to use hlitem.Key.ToString() in your code instead of sitem ?