數據綁定Image.Source不工作

Question

我有以下類PhotoChooserTask結果：

public class Sticky : INotifyPropertyChanged { 

    // ... some members 

    private BitmapImage _frontPic; 
    [DataMember] 
    public BitmapImage FrontPic { 
     get { 
      return _frontPic; 
     } 
     set { 
      _frontPic = value; 
      Changed("FrontPic"); 
      Changed("FrontBrush"); 
     } 
    } 
} 

我試圖把它的數據綁定到這個XAML：推出PhotoChooserTask這個後

<Image Width="173" Height="173" Source="{Binding FrontPic}" /> 

代碼在我的PhoneApplicationPage：

public Sticky Sticky { get; set; } 

protected override void OnNavigatedTo(System.Windows.Navigation.NavigationEventArgs e) { 
    Sticky = new Sticky(); 
    DataContext = Sticky; 
} 

private void ShowFrontPicPicker(object sender, RoutedEventArgs e) { 
    var t = new PhotoChooserTask(); 
    t.PixelHeight = 173; 
    t.PixelWidth = 173; 
    t.ShowCamera = true; 

    t.Completed += (s, ev) => { 
     if (ev.TaskResult == TaskResult.OK) { 
      var img = new BitmapImage(); 
      img.SetSource(ev.ChosenPhoto); 
      Sticky.FrontPic = img; 
     } 
    }; 

    t.Show(); 
} 

但是，我的圖像仍然是空白。如果我將Image.Source屬性直接分配給沒有數據綁定的Image，則一切正常。數據綁定其他屬性的作品，這只是圖像，似乎是問題。我怎樣才能使圖像工作DataBinding？

Answer 1

發現問題！對於PhotoChooserTask完成的回調不會在UI線程excecute，所以Dispatcher.BeginInvoke呼叫必須被添加：

t.Completed += (s, ev) => Dispatcher.BeginInvoke(() => { 
    // do stuff... 
});