如何激活视图时获取？

Question

简单来说，我有一个棱镜模块有几个视图。

其中之一是一个带有网格的用户控件，我需要获取这个视图是否活动来重新加载它的datacontext。

我知道我必须使用IActiveAware接口，但我无法弄清楚如何...

编辑：

MyUserControl.xaml

<UserControl x:Class="[...] 
      mc:Ignorable="d"> 

    <UserControl.Resources> 
     <dc:MyViewModel x:Key="MyViewModel" /> 
    </UserControl.Resources> 

    <Grid DataContext="{StaticResource MyViewModel}"> 
     <Grid.RowDefinitions> 
    [...] 

MyUserControl.xaml .cs

public partial class MyUserControl: UserControl, IActiveAware 
{ 
    public MyUserControl(IRegionManager _regionManager) 
    { 
     regionManager = _regionManager; 
     InitializeComponent();   
    } 

    public event EventHandler<EventArgs> Activated; 

    public event EventHandler<EventArgs> Deactivated; 

    private bool _IsActive; 
    public bool IsActive 
    { 
     get 
     { 
      return _IsActive; 
     } 
     set 
     { 
      _IsActive = value; 
      IActiveAware vmAware = DataContext as IActiveAware; 
      if (vmAware != null) 
       vmAware.IsActive = value; 

     } 
    } 
    public event EventHandler IsActiveChanged = delegate { }; 
[...] 

MyViewModel.cs

public class MyViewModel: IActiveAware 
{ 
    private bool isActive { get; set; } 
    public bool IsActive 
    { 
     get 
     { 
      return isActive; 
     } 
     set 
     { 
      isActive = value; 
      LoadData(); 
      IsActiveChanged(this, EventArgs.Empty); 
     } 
    } 

    public event EventHandler IsActiveChanged = delegate { }; 
[...] 

Answer 1

只需在您的视图模型上实现接口。你也需要实现事件处理程序，但是我没有把它从这个例子中解放出来。你可以在Brian Noyes's blog上看到一个完整的例子。

public class ViewModel : IActiveAware 
{ 
    private bool _isActive; 

    public bool IsActive 
    { 
     get { return _isActive; } 
     get 
     { 
      _isActive = value; 

      // Do Other Stuff e.g. 
      LoadData(); 
     } 
    } 

    private void LoadData() 
    { 
     ..... 
    } 
} 

棱镜看着它被激活视图模型，并确定它是否实现了IActiveAware，如果这样做，这是套IsActive，这样就可以使视图模型，并因此认为，做的东西。