Question

当我使用从PhoneApplicationPage继承的客户页面而不是直接使用它时，datepicker会抛出空引用异常...

我的自定义课程：

public class CustomPhoneApplicationPage : PhoneApplicationPage
{
  public CustomPhoneApplicationPage()
  {
      Loaded += CustomPhoneApplicationPageLoaded;
      IsAnimFromDisabled = false;
      IsAnimToDisabled = false;
      this.Tap += CustomPhoneApplicationPageTap;
      InitTransition();
  }
  private void InitTransition()
  {
    RenderTransform = new CompositeTransform();
    _comeInStoryboard = Application.Current.Resources["FadeIn"] as Storyboard;
    _comeOutStoryboard = Application.Current.Resources["FadeOut"] as Storyboard;
    Debug.Assert(_comeInStoryboard != null, "_comeInStoryboard != null");
    Debug.Assert(_comeOutStoryboard != null, "_comeOutStoryboard != null");
  }
}

在Xaml中使用日期选择器：

<toolkit:DatePicker x:Name="_dateTimePicker" Value="{Binding SnapshotTime, Mode=TwoWay}" />

此处抛出异常：

Microsoft.Phone.Controls.Toolkit.dll！Microsoft.Phone.Controls.DataSource.GetPrevious（object relativeTo）+ 0x7 bytes

以下是我如何使用此类作为应用程序中我的页面的基础：

public partial class AddOrEditData : CustomPhoneApplicationPage
{


    public AddOrEditData()
    {
        InitializeComponent();
        Loaded += AddOrEditDataLoaded;

    }
...
}

这是完整的堆栈跟踪：

Microsoft.Phone.Controls.Toolkit.dll！Microsoft.Phone.Controls.DataSource.GetPrevious（object relativeTo）第58行+ 0x7字节C＃ Microsoft.Phone.Controls.Toolkit.dll！Microsoft.Phone.Controls.Primitives.LoopingSelector.Balance（）第146行+ 0xd字节C＃ Microsoft.Phone.Controls.Toolkit.dll！Microsoft.Phone.Controls.Primitives.LoopingSelector.UpdateData（）第552行+ 0xc0字节C＃ Microsoft.Phone.Controls.Toolkit.dll！Microsoft.Phone.Controls.Primitives.LoopingSelector.LoopingSelector_SizeChanged（object sender，System.Windows.SizeChangedEventArgs e）Line 365 C＃ System.Windows.dll！System.Windows.FrameworkElement.OnSizeChanged（object sender，System.Windows.SizeChangedEventArgs e）+ 0x15 bytes System.Windows.dll！MS.Internal.JoltHelper.RaiseEvent（System.IntPtr target，uint eventId，System.IntPtr coreEventArgs，uint eventArgsTypeIndex）+ 0xb2 bytes [原生于管理过渡]

Answer 1

确定，

我通过将这行代码添加到我的继承页面来解决它，以便在离开页面时禁用一些自定义动画：

 protected override void OnNavigatingFrom(System.Windows.Navigation.NavigatingCancelEventArgs e)
    {
        IsAnimFromDisabled = e.Uri.OriginalString == @"/Microsoft.Phone.Controls.Toolkit;component/DateTimePickers/DatePickerPage.xaml";
        base.OnNavigatingFrom(e);
    }

它有效！

谢谢大家！

当我的页面继承自PhoneApplicationPage时，WP7 Silverlight工具包日期选择器抛出空引用异常

1 个答案: