綁定的MediaElement和滑塊值

Question

我如下已經實現附加屬性當其值改變時改變所述媒體元素的位置..

附加屬性被定義：

public class MediaElementHelper 
{ 
    public static void SetBindablePosition(UIElement element, TimeSpan value) 
    { 
     if (element == null) 
     { 
      throw new ArgumentNullException(); 
     } 
     element.SetValue(BindablePositionProperty, value); 
    } 

    public static TimeSpan GetBindablePosition(UIElement element) 
    { 
     if (element == null) 
     { 
      throw new ArgumentNullException(); 
     } 
     return (TimeSpan) element.GetValue(BindablePositionProperty); 
    } 

    private static void PostionPropertyChanged(DependencyObject obj, DependencyPropertyChangedEventArgs e) 
    { 
     var richEditControl = obj as MediaElement; 

     if (richEditControl != null) 
     { 
      richEditControl.Position = (TimeSpan) e.NewValue; 
     } 
    } 

    public static readonly DependencyProperty BindablePositionProperty = 
     DependencyProperty.RegisterAttached("BindablePosition", 
      typeof (TimeSpan), typeof (MediaElementHelper), 
      new FrameworkPropertyMetadata(new TimeSpan(), FrameworkPropertyMetadataOptions.BindsTwoWayByDefault, 
       PostionPropertyChanged)); 
} 

}

並在主窗口：

public partial class MainWindow : Window 
{ 
    public MainWindow() 
    { 
     InitializeComponent(); 
    } 

    private void Button_OnClick(object sender, RoutedEventArgs e) 
    { 
     var newFileDialog = new OpenFileDialog(); 
     newFileDialog.ShowDialog(); 
     MediaElement.Source = new Uri(newFileDialog.FileName); 
    } 

    private void MediaElement_OnMediaOpened(object sender, RoutedEventArgs e) 
    { 
     Slider.Maximum = MediaElement.NaturalDuration.TimeSpan.TotalMilliseconds; 
     Slider.SmallChange = 1; 
     Slider.LargeChange = 5000; 
    } 
} 

，並在XAML：

<MediaElement Name="MediaElement" 
        Grid.Row="0" 
        loc:MediaElementHelper.BindablePosition="{Binding ElementName=Slider, Path=Value, Converter={StaticResource DoubleToTimeSpanConverter}}" 
        MediaOpened="MediaElement_OnMediaOpened" /> 

我的轉換器類的定義如下：但

public class DoubleToTimeSpanConverter : IValueConverter 
{ 
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture) 
    { 
     return TimeSpan.FromMilliseconds((double) value); 
    } 

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture) 
    { 
     return System.Convert.ToDouble(((TimeSpan) value).Milliseconds); 
    } 
} 

，當我拖着滑塊的拇指它工作得很好，但是當我做什麼，滑塊的拇指不會自動移動。什麼我應該怎麼做這個綁定作爲拖曳方式綁定？

Answer 1

沒有完美的方式 - 我過去解決它的方法是創建一個新的DispatcherTimer對象，輪詢Position元素，並更新滑塊。

// this is the timer 
timerVideoTime = new DispatcherTimer(); 
      timerVideoTime.Interval = TimeSpan.FromSeconds(1); 
      timerVideoTime.Tick += new EventHandler(timer_Tick); 
      timerVideoTime.Start(); 
     } 

// the actual timer handler. 
void timer_Tick(object sender, EventArgs e) 
     { 
      // Check if the movie finished calculate it's total time 
      if (MyMediaElement.NaturalDuration.TimeSpan.TotalSeconds > 0) 
      { 
       if (TotalTime.TotalSeconds > 0) 
       { 
        var sliderValue = MyMediaElement.Position.TotalSeconds/
             TotalTime.TotalSeconds; 

        if(Slider.Value != sliderValue){ 
         Slider.SetCurrentValue(Slider.ValueProperty, sliderValue); 
        } 
       } 
      }