# 展示TreeView的視窗

class SimpleTreeViewWindow : EditorWindow
{
    [MenuItem("TreeView Examples/Simple Tree View Window")]
    static void ShowWindow()
    {
        var window = GetWindow<SimpleTreeViewWindow>();
        window.titleContent = new GUIContent("My Window");
        window.Show();
    }

    SimpleTreeView _tableView;
    TreeViewState _treeViewState;

    
 
private void OnEnable()
    {
        if (null == _treeViewState)
            _treeViewState = new TreeViewState(); //單獨用一個類, 以便於序列化狀態

        _tableView = new SimpleTreeView(_treeViewState);
    }

    private void OnGUI()
    {
        var xMargin = 10;
        var yMargin = 10;
        var rect = new
 
 Rect(xMargin, yMargin, position.width - xMargin * 2, position.height - yMargin * 2);
        _tableView.OnGUI(rect);
    }

}

# TreeView

(#) BuildRoot必須重寫

(#) 沒有重寫RowGUI的情況下，預設實現將直接用Label展示TreeViewItem的displayName

class SimpleTreeView : TreeView
{
    public SimpleTreeView(TreeViewState state)
        : 
 
base(state)
    {
        //rowHeight = 35;
        showAlternatingRowBackgrounds = true; //隔行顯示顏色
        showBorder = true; //表格邊框
        Reload();
    }

    protected override TreeViewItem BuildRoot()
    {
        var rootTreeViewItem = new TreeViewItem(-1, -1); //root的depth必須為-1

        var rows = new List<TreeViewItem>();
        for (var i = 0; i < 10; ++i)
        {
            rows.Add(new TreeViewItem(i, i % 3, $"index {i}"));
        }
        SetupParentsAndChildrenFromDepths(rootTreeViewItem, rows); //根據depth自動調整TreeViewItem間的父子關係

        return rootTreeViewItem;
    }

}

# 效果圖