Question

我正在使用带有此datatemplate的列表框开发Windows Phone 8应用程序：

<phone:PhoneApplicationPage.Resources>
    <DataTemplate x:Key="LocalizationItemTemplate">
        <Border BorderBrush="Black" BorderThickness="2" CornerRadius="8" Background="#FF003847" Height="80">
            <StackPanel x:Name="contentGrid" Margin="4" Orientation="Horizontal">
                <CheckBox x:Name="selectedCheck" Visibility="{Binding CheckBoxVisibility}" IsChecked="{Binding IsChecked}"
                        HorizontalAlignment="Left" Margin="10,0,0,0" VerticalAlignment="Center" IsEnabled="False"/>
                <TextBlock x:Name="locationName" TextWrapping="Wrap" Text="{Binding Content}" VerticalAlignment="Center" FontSize="24" HorizontalAlignment="Left" Margin="10,0,0,0"/>
            </StackPanel>
        </Border>
    </DataTemplate>
</phone:PhoneApplicationPage.Resources>

我使用ObservableCollection<LocationToShow>作为ItemsSource：

public class LocationToShow : ARItem
{
    public double Distance { get; set; }

    public string FormatedDistance
    {
        get
        {
            if (Distance == double.NaN)
                return string.Empty;
            else
                return string.Format("{0} metros", Distance.ToString("N0"));
        }
    }

    public Visibility CheckBoxVisibility { get; set; }

    public bool IsChecked { get; set; }
}

但是，当我更改CheckBoxVisibility或IsChecked时，我看不到复选框或检查它。

如何解决此问题？

Answer 1

LocationToShow或ARItem类需要实现INotifyPropertyChanged接口，每次视图模型属性更改值时，您需要引发PropertyChanged事件：

public event PropertyChangedEventHandler PropertyChanged;

private void NotifyPropertyChanged(String propertyName)
{
    var handler = PropertyChanged;
    if (handler != null)
        handler(this, new PropertyChangedEventArgs(propertyName));
}

private bool _isChecked;

public bool IsChecked 
{ 
    get { return _isChecked; }
    set
    {
        if (_isChecked != value)
        {
            _isChecked = value;
            NotifyPropertyChanged("IsChecked");
        }
    }
}

Answer 2

在您的班级INotifyPropertyChanged上实施LocationToShow，以通知用户界面更新任何属性更改。

请参阅此 - How to Implement INotifyPropertyChanged notification。

public class LocationToShow : ARItem, INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;
    // Create the OnPropertyChanged method to raise the event 
    protected void OnPropertyChanged(string name)
    {
        PropertyChangedEventHandler handler = PropertyChanged;
        if (handler != null)
        {
           handler(this, new PropertyChangedEventArgs(name));
        }
     }

     private bool isChecked;
     public bool IsChecked 
     { 
         get { return isChecked; }
         set
         {
            if (isChecked != value)
            {
               isChecked = value;
               OnPropertyChanged("IsChecked");
            }
         }
     }
}

更改所有其他属性以遵循相同的模式，以防您希望在类中的任何属性更改时刷新UI。

绑定CheckBox.Visibility和CheckBox.IsChecked

2 个答案: