Terminal.Gui/docfx/articles/treeview.md

Tree View

TreeView is a control for navigating hierarchical objects. It comes in two forms TreeView and TreeView<T>.

TreeView

The basic non generic TreeView class is populated by ITreeNode objects. The simplest tree you can make would look something like:

var tree = new TreeView()
{
    X = 0,
    Y = 0,
    Width = 40,
    Height = 20
};

Win.Add(tree);

var root1 = new TreeNode("Root1");
root1.Children.Add(new TreeNode("Child1.1"));
root1.Children.Add(new TreeNode("Child1.2"));

var root2 = new TreeNode("Root2");
root2.Children.Add(new TreeNode("Child2.1"));
root2.Children.Add(new TreeNode("Child2.2"));

tree.AddObject(root1);
tree.AddObject(root2);

Having to create a bunch of TreeNode objects can be a pain especially if you already have your own objects e.g. House, Room etc. There are two ways to use your own classes without having to create nodes manually. Firstly you can implement the ITreeNode interface:

// Your data class
private class House : ITreeNode {


    // Your properties
    public string Address {get;set;}
    public List<Room> Rooms {get;set;}

    // ITreeNode member:

    public IList<ITreeNode> Children => Rooms.Cast<ITreeNode>().ToList();
    
    public override string ToString ()
    {
        return Address;
    }
}

// Your other data class
private class Room : ITreeNode{
    
    public string Name {get;set;}


    // Rooms have no sub objects
    public IList<ITreeNode> Children => new List<ITreeNode>();

    public override string ToString ()
    {
        return Name;
    }
}


...

// After implementing the interface you can add your objects directly to the tree

var myHouse = new House()
{
    Address = "23 Nowhere Street",
    Rooms = new List<Room>{
        new Room(){Name = "Ballroom"},
        new Room(){Name = "Bedroom 1"},
        new Room(){Name = "Bedroom 2"}
    }
};

var tree = new TreeView()
{
    X = 0,
    Y = 0,
    Width = 40,
    Height = 20
};

tree.AddObject(myHouse);

Alternatively you can simply tell the tree how the objects relate to one another by implementing ITreeBuilder. This is a good option if you don't have control of the data objects you are working with:

TODO

TreeView