如何在另一个线程之间切换视图？

Question

我试图使用MVVM，所以我有：

主窗口：

<Window x:Class="tbtest.MainWindow" 
     xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
     Title="MainWindow" Height="350" Width="525"> 
    <Grid> 
     <Grid.RowDefinitions> 
      <RowDefinition Height="*" /> 
      <RowDefinition Height="Auto" /> 
     </Grid.RowDefinitions> 
     <TabControl ItemsSource="{Binding Tabs}" IsSynchronizedWithCurrentItem="True" Grid.Row="0"/> 
     <Button Command="{Binding AddNewTab}" Grid.Row="1">Add new tab</Button> 
    </Grid> 
</Window> 

和视图模型：

public class VM 
{ 
    public VM() 
    { 
     Tabs = new ObservableCollection<Object>(); 
     AddNewTab = new DelegateCommand<object>(ExecAddNewTab); 
    } 

    private void ExecAddNewTab(object obj) 
    { 
     var tab = new SomeTab(); 
     Tabs.Add(tab.View); 
     ThreadPool.QueueUserWorkItem(item => tab.Activate()); 
    } 

    public ObservableCollection<Object> Tabs { get; private set; } 
    public DelegateCommand<object> AddNewTab { get; private set; } 
} 

每个选项卡是独立的视图模型与景观：

public class SomeTab : ITab, INotifyPropertyChanged 
{ 
    public SomeTab() 
    { 
     View = new SomeTabView1 {DataContext = this}; 
    } 

    public string Header { get { return "Header"; } } 
    private object _view; 
    public object View 
    { 
     get { return _view; } 
     private set 
     { 
      _view = value; 
      PropertyChanged(this, new PropertyChangedEventArgs("View")); 
     } 
    } 

    public void Activate() 
    { 
     Thread.Sleep(2000); 

     // Some work 

     Application.Current.Dispatcher.BeginInvoke(new Action<SomeTab>(vm => 
                    { 
// switching views, how can it be done? 
                      vm.View = new SomeTabView2 { DataContext = this }; 

                    }), this); 
    } 

    public event PropertyChangedEventHandler PropertyChanged = delegate { }; 
} 

SomeTabView1 And SomeTabView2 are si使用TextBlock的'View1'和'View2'实现多个WPF UserControl。

我需要的是在Activate方法（即在单独的线程中运行）将View1切换到View2。
我提供的这段代码不起作用。

我该怎么做才能满足需求？谢谢。

Answer 1

上面的问题是由于您的代码是“假设”它将通过简单地使用IsSynchronizedWithCurrentItem选择\专注新创建的Tab项目。

您需要将该字段替换为CollectionView。你也应该使用这个CollectionView本身添加新标签。

E.g.

假设你有一个叫ListCollectionView与TabsView源集合为Tabs观察到的集合......

绑定TabControl.ItemsSource到TabsView，然后代替......

var tab = new SomeTab(); 
    Tabs.Add(tab.View); 

使用此...

var tabUi = this.TabsView.AddNew() as SomeTab; 
    this.TabsView.CommitNew(); 
    tabUi.Activate(); 

让我知道这是否有帮助....

周

Answer 2

你的ViewModels不应该查看

工作相反，有你MainViewModel包含SelectedTab属性，并将其绑定到你的TabControl，然后切换选项卡，你只设置SelectedTab。使用DataTemplates告诉WPF如何绘制每个视图模型

主窗口XAML

<Window x:Class="tbtest.MainWindow" 
     xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
     Title="MainWindow" Height="350" Width="525" 
     xmlns:local=clr-namespace:MyNamespace> 

    <Window.Resources> 
     <DataTemplate DataType="{x:Type local:SomeTabViewModel1}"> 
      <local:SomeTabView1 /> 
     </DataTemplate> 
     <DataTemplate DataType="{x:Type local:SomeTabViewModel2}"> 
      <local:SomeTabView2 /> 
     </DataTemplate> 
     </DataTemplate> 
     <DataTemplate DataType="{x:Type local:SomeTabViewModel3}"> 
      <local:SomeTabView3 /> 
     </DataTemplate> 
    </Window.Resources> 

    <Grid> 
     <Grid.RowDefinitions> 
      <RowDefinition Height="*" /> 
      <RowDefinition Height="Auto" /> 
     </Grid.RowDefinitions> 
     <TabControl ItemsSource="{Binding Tabs}" SelectedItem="{Binding SelectedTab}" 
        IsSynchronizedWithCurrentItem="True" Grid.Row="0"/> 
     <Button Command="{Binding AddNewTab}" Grid.Row="1">Add new tab</Button> 
    </Grid> 
</Window> 

主窗口视图模型

public class VM 
{ 
    public VM() 
    { 
     Tabs = new ObservableCollection<Object>(); 
     AddNewTab = new DelegateCommand<object>(ExecAddNewTab); 
    } 

    private void ExecAddNewTab(object obj) 
    { 
     var tab = new SomeTab(); 
     Tabs.Add(tab); 
     SelectedTab = tab; 

     // This should only run whatever code is needed to initialize the 
     // ViewModel. It should have nothing to do with views 
     ((ITab)tab).Activate(); 
    } 

    public object SelectedTab { get; private set; } 
    public ObservableCollection<Object> Tabs { get; private set; } 
    public DelegateCommand<object> AddNewTab { get; private set; } 
}