c# - 带有 ContextMenu ItemCollection 的 WPF 自定义控件

Question

我正在尝试创建类似可扩展按钮 - 上面带有上下文菜单的按钮，该按钮将通过单击鼠标左键打开。唯一我仍然无法完成的是 items 属性，它可以在 WPF XAML 设计器中设置，例如用于ContextMenu控制。所以，据我所知，这意味着我需要ItemCollection为我的属性使用类型。好的。让我们看一下我的组件：

public partial class MenuButton : Button
{
    private readonly ContextMenu Menu;

    public static readonly DependencyProperty MenuItemsProperty =
        DependencyProperty.Register("MenuItems", typeof(ItemCollection), typeof(ContextMenu), new PropertyMetadata(default(ItemCollection), new PropertyChangedCallback(OnSomeMenuItemsPropertyChanged)));

    public ItemCollection MenuItems
    {
        get => (ItemCollection)GetValue(MenuItemsProperty);
        set => SetValue(MenuItemsProperty, value);
    }

    public MenuButton()
    {
        MenuItems = new DataGrid().Items; // I really need to do it - otherwise I'll get an error

        Menu = new ContextMenu
        {
            HasDropShadow = false,
            PlacementTarget = this,
            Placement = PlacementMode.Top,
        };

        InitializeComponent();
    }

    protected override void OnMouseLeftButtonDown(MouseButtonEventArgs e)
    {
        base.OnMouseLeftButtonDown(e);

        Menu.Width = ActualWidth;
        Menu.IsOpen = true;
    }

    private static void OnSomeMenuItemsPropertyChanged(DependencyObject target, DependencyPropertyChangedEventArgs e)
    {
        if (target is ContextMenu menu)
        {
            menu.ItemsSource = (ItemCollection)e.NewValue;
        }
    }
}

但我无法“捕捉” OnSomeMenuItemsPropertyChanged- 断点在这里不起作用。所以，这意味着这个机制是错误的。我该如何解决？我应该使用OnItemsChangedandOnItemsCollectionChanged事件（例如 for ObservableCollection）来处理属性的更改吗？或者也许是别的什么？

Answer 1

所以，最后我找到了解决方案。我并没有声称这是最佳实践，但也许它对某人有用：

public partial class MenuButton : Button
{
    private readonly ContextMenu Menu;

    public static readonly DependencyProperty MenuItemsProperty =
        DependencyProperty.Register("MenuItems", typeof(ItemCollection), typeof(MenuButton), new PropertyMetadata(default(ItemCollection), new PropertyChangedCallback(OnSomeMenuItemsPropertyChanged)));

    public ItemCollection MenuItems
    {
        get => (ItemCollection)GetValue(MenuItemsProperty);
        set => SetValue(MenuItemsProperty, value);
    }

    public MenuButton()
    {
        Menu = new ContextMenu
        {
            HasDropShadow = false,
            PlacementTarget = this,
            Placement = PlacementMode.Top,
        };
        MenuItems = new DataGrid().Items;

        InitializeComponent();
    }

    protected override void OnMouseLeftButtonDown(MouseButtonEventArgs e)
    {
        base.OnMouseLeftButtonDown(e);

        Menu.Width = ActualWidth;
        Menu.IsOpen = true;
    }

    private static void OnSomeMenuItemsPropertyChanged(DependencyObject target, DependencyPropertyChangedEventArgs e)
    {
        var menuButton = target as MenuButton;
        menuButton.Menu.ItemsSource = (ItemCollection)e.NewValue;
    }
}