ShrlAlgoToolkit/Wpf.Ui.Extend/Controls/TreeComboBox/TreeComboBox.cs

using System;
using System.Collections;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Input;

namespace Wpf.Ui.Extend.Controls;
public class TreeComboBox : ComboBox
{
    public static readonly DependencyProperty SelectedItemsProperty = DependencyProperty.Register("SelectedItems", typeof(IEnumerable), typeof(TreeComboBox), new PropertyMetadata(null));
    public static readonly DependencyProperty ParentPathProperty = DependencyProperty.Register("ParentPath", typeof(string), typeof(TreeComboBox), new PropertyMetadata());
    public static readonly DependencyProperty SelectedNodeProperty = DependencyProperty.Register("SelectedNode", typeof(object), typeof(TreeComboBox), new FrameworkPropertyMetadata(default));
    public static readonly DependencyProperty IsCheckedPathProperty = DependencyProperty.Register("IsCheckedPath", typeof(string), typeof(TreeComboBox), new PropertyMetadata());
    public static readonly DependencyProperty IsExpandedPathProperty = DependencyProperty.Register("IsExpandedPath", typeof(string), typeof(TreeComboBox), new PropertyMetadata("IsExpanded"));
    public static readonly DependencyProperty IsSelectedPathProperty = DependencyProperty.Register("IsSelectedPath", typeof(string), typeof(TreeComboBox), new PropertyMetadata("IsSelected"));

    private ExtendedTreeView _treeView;
    private ObservableCollection<object> list = [];

    static TreeComboBox()
    {
        DefaultStyleKeyProperty.OverrideMetadata(typeof(TreeComboBox), new FrameworkPropertyMetadata(typeof(TreeComboBox)));
    }

    protected override void OnMouseWheel(MouseWheelEventArgs e)
    {
        //don't call the method of the base class
    }

    public override void OnApplyTemplate()
    {
        _treeView = (ExtendedTreeView)this.GetTemplateChild("treeView");
        _treeView.OnHierarchyMouseUp += new MouseEventHandler(OnTreeViewHierarchyMouseUp);
        _treeView.OnChecked += _treeView_OnChecked;
        this.UpdateSelectedItem();
        base.OnApplyTemplate();
    }

    private void _treeView_OnChecked(object sender, RoutedEventArgs e)
    {
        if (sender is CheckableTreeViewItem { IsChecked: bool isChecked } item)
        {
            if (isChecked)
            {
                list.Add(item.DataContext);
            }
            else if (list.Contains(item))
            {
                list.Remove(item.DataContext);
            }
            SelectedItems = list;
        }
    }

    protected override void OnDropDownClosed(EventArgs e)
    {
        base.OnDropDownClosed(e);
        this.UpdateSelectedItem();
    }

    protected override void OnDropDownOpened(EventArgs e)
    {
        base.OnDropDownOpened(e);
        this.UpdateSelectedItem();
    }

    /// <summary>
    /// Handles clicks on any item in the tree view
    /// </summary>
    private void OnTreeViewHierarchyMouseUp(object sender, MouseEventArgs e)
    {
        var hierarchy = SelectItems();
        this.SelectedItem = hierarchy.First();
        this.SelectedItems = hierarchy;
        UpdateSelectedItem();
        this.IsDropDownOpen = false;
        this.SelectedNode = _treeView.SelectedItem;
    }

    #region properties

    public string IsExpandedPath
    {
        get { return (string)GetValue(IsExpandedPathProperty); }
        set { SetValue(IsExpandedPathProperty, value); }
    }

    public string IsSelectedPath
    {
        get { return (string)GetValue(IsSelectedPathProperty); }
        set { SetValue(IsSelectedPathProperty, value); }
    }

    public string IsCheckedPath
    {
        get { return (string)GetValue(IsCheckedPathProperty); }
        set { SetValue(IsCheckedPathProperty, value); }
    }

    public string ParentPath
    {
        get { return (string)GetValue(ParentPathProperty); }
        set { SetValue(ParentPathProperty, value); }
    }

    public object SelectedNode
    {
        get { return GetValue(SelectedNodeProperty); }
        set { SetValue(SelectedNodeProperty, value); }
    }

    public IEnumerable SelectedItems
    {
        get { return (IEnumerable)GetValue(SelectedItemsProperty); }
        set { SetValue(SelectedItemsProperty, value); }
    }


    #endregion properties

    private void UpdateSelectedItem()
    {
        if (_treeView.SelectedItem != null)
        {
            var hierarchy = SelectItems();
            SelectedItems = hierarchy;
            SelectedNode = hierarchy.Last();
        }
    }

    private object[] SelectItems()
    {
        var type = _treeView.SelectedItem.GetType();
        var propInfo = type.GetProperty(ParentPath);
        return TreeHelper.GetAncestors(_treeView.SelectedItem, a => propInfo.GetValue(a)).Reverse().ToArray();
    }

    static class TreeHelper
    {
        public static IEnumerable<object> GetAncestors(object vm, Func<object, object> parent)
        {
            yield return vm;
            while (parent(vm) != null)
            {
                yield return parent(vm);
                vm = parent(vm);
            }
        }
    }
}