Wpf：我怎么知道 TreeView 是否已更新？

Question

我正在使用 Wpf TreeView，在此我可以动态添加 TreeViewItems。 有什么方法可以知道树何时更新？我尝试使用与 TreeView 绑定的 ObservableCollection 的 CollectionChanged 事件，但没有成功。

编辑：

我的代码是这样的：

class Temp
{
    public void Load()
    {
        DeriveA d1 = new DeriveA();
        DeriveB d2 = new DeriveB();
        DeriveB d3 = new DeriveB();
        DeriveC d4 = new DeriveC();
        DeriveC d5 = new DeriveC();
        d1.Items.Add(d2);
        d1.Items.Add(d3);
        d2.Items.Add(d4);
        d2.Items.Add(d5);
        
        List = new ObservableCollection<object>();
        List.Add(d1);
        tree.ItemsSource = List;

        DeriveC d6 = new DeriveC();
        d3.Items.Add(d6);        //At this point, I want to know that List got updated
    }
    
    public ObservableCollection<object> List
    {
        get;
        set;
    }
}

class Base
{
    ObservableCollection<Base> Items = new ObservableCollection<Base>();
}

class DeriveA : Base
{
}

class DeriveB : Base
{
}

class DeriveC : Base
{
}

我如何知道 List 属性何时在任何级别更新？

Answer 1

你可以有这样的东西：

private void Loaded()
{
    MyTreeNode d1 = new MyTreeNode();
    MyTreeNode d2 = new MyTreeNode();
    MyTreeNode d3 = new MyTreeNode();
    MyTreeNode d4 = new MyTreeNode();
    MyTreeNode d5 = new MyTreeNode();
    d1.AddNode(d2);
    d1.AddNode(d3);
    d2.AddNode(d4);
    d2.AddNode(d5);

    d1.CollectionChanged += (s, e) =>
    {
        MessageBox.Show("Tree Changed");
    };

    MyTreeNode d6 = new MyTreeNode();
    d3.AddNode(d6);
}  

public class MyTreeNode : ObservableCollection<MyTreeNode>
{
    public void AddNode(MyTreeNode node)
    {
        this.Add(node);
        node.CollectionChanged += (s, e) => this.OnCollectionChanged(e);
    }
}

Answer 2

SourceUpdated 事件呢？

---

编辑 SourceUpdated 事件不会触发，但我尝试使用 ObservableCollection.CollectionChanged 并且没问题，所以我想提供一些你的代码，这是我测试过的，希望对您有所帮助：

public partial class Window1 : Window
{
    ObservableCollection<string> items = new ObservableCollection<string>()
    {
        "string1","string2","string3","string4","string5"
    };
    public Window1()
    {
        InitializeComponent();
        DataContext = this;
        tree.ItemsSource = items;
        items.CollectionChanged += new System.Collections.Specialized.NotifyCollectionChangedEventHandler(items_CollectionChanged);
    }

    void items_CollectionChanged(object sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e)
    {
        MessageBox.Show("Event raised");
    }


    private void btnAddItem_Click(object sender, RoutedEventArgs e)
    {
        items.Add("string6");
    }
}

和 xaml

<StackPanel Orientation="Vertical">
            <TreeView x:Name="tree" />
            <Button x:Name="btnAddItem" Click="btnAddItem_Click" Content="AddItem" />
</StackPanel>