Question

在我的应用程序中，当加载了ICommand或UserControl时，我具有以下附加属性可以调用Window：

public static readonly DependencyProperty LoadedCommandProperty = DependencyProperty.RegisterAttached(
    "LoadedCommand", typeof(ICommand), typeof(UserControlExtensions), new PropertyMetadata(null, OnLoadedCommandChanged));

private static void OnLoadedCommandChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
    ContentControl userControl = d as ContentControl;
    if (userControl == null)
        return;

    if (e.NewValue is ICommand)
    {
        userControl.Loaded += UserControlOnLoaded;
    }
}

private static void UserControlOnLoaded(object sender, RoutedEventArgs e)
{
    ContentControl userControl = sender as ContentControl;
    if (userControl == null)
        return;

    ICommand command = GetLoadedCommand(userControl);
    command.Execute(GetLoadedCommandParameter(userControl));
}

public static void SetLoadedCommand(DependencyObject element, ICommand value)
{
    element.SetValue(LoadedCommandProperty, value);
}

public static ICommand GetLoadedCommand(DependencyObject element)
{
    return (ICommand) element.GetValue(LoadedCommandProperty);
}

public static readonly DependencyProperty LoadedCommandParameterProperty = DependencyProperty.RegisterAttached(
    "LoadedCommandParameter", typeof(object), typeof(UserControlExtensions), new PropertyMetadata(default(object)));

public static void SetLoadedCommandParameter(DependencyObject element, object value)
{
    element.SetValue(LoadedCommandParameterProperty, value);
}

public static object GetLoadedCommandParameter(DependencyObject element)
{
    return (object) element.GetValue(LoadedCommandParameterProperty);
}

这很好用。在我看来，我用UserControl来称呼它，例如：

AttachedProperties:UserControlExtensions.LoadedCommand="{Binding ViewLoadedCommand}"

然后将调用viewmodel中的ICommand。

现在，我实现了一项功能，可以单击Button标头中的TabItem，然后在新窗口中打开此TabItem的内容。（就像在视觉工作室中取消停靠一个标签页一样。）

因此，我正在使用以下代码：

private void OpenInWindowButtonOnClick(object sender, RoutedEventArgs e)
{
    Button button = sender as Button;
    if (button == null)
        return;

    TabItem tabItem = button.Tag as TabItem;
    if (tabItem == null)
        return;

    string title = string.Empty;

    ContentControl headerContent = tabItem.Header as ContentControl;
    if (headerContent != null)
    {
        title = headerContent.Content.ToString();
    }

    string workspaceId = tabItem.Tag as string;

    TabItem workspaceTab = WorkspaceTab.Items.OfType<TabItem>()
        .FirstOrDefault(ti => ti.Tag is string && (string)ti.Tag == workspaceId);
    if (workspaceTab != null)
    {
        WorkspaceWindow workspaceWindow = new WorkspaceWindow(tabItem);
        workspaceWindow.Content = workspaceTab.Content;

        workspaceWindow.Width = (workspaceTab.Content as FrameworkElement).ActualWidth;
        workspaceWindow.Height = (workspaceTab.Content as FrameworkElement).ActualHeight;

        workspaceWindow.Title = title;
        workspaceWindow.Closing += WorkspaceWindowOnClosing;
        workspaceWindow.Show();
        workspaceWindows.Add(workspaceId, workspaceWindow);
        WorkspaceTab.Items.Remove(workspaceTab);
    }
}

这也很好。

我现在的问题是，如果我打开一个新标签页（女巫还包含TabControl，其中TabItem具有已加载的附加属性），然后使用上面的代码将此标签页移动到新窗口：当我切换到使用已加载属性的视图时，将不会调用该加载命令。

如果我调试附加属性，可以看到正确调用了OnLoadedCommandChanged，但未调用UserControlOnLoaded。如果我没有在新窗口中打开TabItem，则会正确调用UserControlOnLoaded。

有什么主意，如果我将TabItem移到新的Window时为什么子页面的加载事件不会被触发？

Answer 1

问题出在WorkspaceTab.Items.Remove(workspaceTab);

行内

此行从TabItem中删除了TabControl，看来wpf在这里做了某种清理。

我已经解决了仅将Visibility中的TabItem设置为“隐藏”的问题。

在新窗口中打开TabItem

1 个答案: