ScrollViewer не прокручивается наверх

Question

ScrollViewer не прокручивается до наверх. Любая подсказка?

UserControl

public class AniScrollViewer : ScrollViewer 
    { 
     //Register a DependencyProperty which has a onChange callback 
     public static DependencyProperty CurrentVerticalOffsetProperty = DependencyProperty.Register("CurrentVerticalOffset", typeof(double), typeof(AniScrollViewer), new PropertyMetadata(new PropertyChangedCallback(OnVerticalChanged))); 
     public static DependencyProperty CurrentHorizontalOffsetProperty = DependencyProperty.Register("CurrentHorizontalOffsetOffset", typeof(double), typeof(AniScrollViewer), new PropertyMetadata(new PropertyChangedCallback(OnHorizontalChanged))); 

     //When the DependencyProperty is changed change the vertical offset, thus 'animating' the scrollViewer 
     private static void OnVerticalChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) 
     { 
      AniScrollViewer viewer = d as AniScrollViewer; 
      viewer.ScrollToVerticalOffset((double)e.NewValue); 
     } 

     //When the DependencyProperty is changed change the vertical offset, thus 'animating' the scrollViewer 
     private static void OnHorizontalChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) 
     { 
      AniScrollViewer viewer = d as AniScrollViewer; 
      viewer.ScrollToHorizontalOffset((double)e.NewValue); 
     } 


     public double CurrentHorizontalOffset 
     { 
      get { return (double)this.GetValue(CurrentHorizontalOffsetProperty); } 
      set { this.SetValue(CurrentHorizontalOffsetProperty, value); } 
     } 

     public double CurrentVerticalOffset 
     { 
      get { return (double)this.GetValue(CurrentVerticalOffsetProperty); } 
      set { this.SetValue(CurrentVerticalOffsetProperty, value); } 
     } 

    } 

Главный код

public partial class Window1 : Window 
    { 
     Random rnd = new Random(); 
     private const int _ITEM_COUNT = 20; 
     Point relativePoint; 
     Storyboard sb = new Storyboard(); 
     Button btn; 

     public Window1() 
     { 
      InitializeComponent(); 
      sb.Completed += (o, s) => ScrollItems(); 

      //Create some buttons ;) 
      for (int i = 0; i < _ITEM_COUNT; i++) 
      { 
       Button btn = CreateButton(i); 
       ListViewItem item = new ListViewItem(); 
       item.Tag = btn; 
       item.Content = "Button " + i.ToString(); 
       cbJumpTo.Items.Add(item); 
       mainContent.Children.Add(btn); 
      } 

      labelH.Content = mainViewer.Height; 
     } 

     /// <summary> 
     /// Create a new button... There are some properties that need to be set, since this is a 
     /// SIMPLE demo, this should be fine. 
     /// </summary> 
     /// <param name="index">index of the button</param> 
     /// <returns>Created button</returns> 
     private Button CreateButton(int index) 
     { 
      Button btn = new Button(); 
      btn.Content = "Button " + index.ToString(); 
      int h = rnd.Next(30, 500); 
      btn.Height = h; 
      btn.Margin = new Thickness(5); 
      return btn; 
     } 
     /// <summary> 
     /// Animate the scrollviewer the the selected item from the combobox 
     /// </summary> 
     /// <param name="sender"></param> 
     /// <param name="e"></param> 
     private void btnAnimate_Click(object sender, RoutedEventArgs e) 
     { 
      //Get the position of the button located in the tag 
      btn = ((ListViewItem)cbJumpTo.SelectedItem).Tag as Button; 
      relativePoint = btn.TransformToAncestor(mainContent).Transform(new Point(0, 0)); 
      ScrollToPosition(relativePoint.X, relativePoint.Y); 
     } 

     /// <summary> 
     /// Create a new animation to the x,y offset. I beleive you need the have .NET 3.5 SP1 installed for 
     /// this to work. If you don't you can't call Storyboard.SetTarget. 
     /// </summary> 
     /// <param name="x">X position</param> 
     /// <param name="y">Y position</param> 
     private void ScrollToPosition(double x, double y) 
     { 

      DoubleAnimation vertAnim = new DoubleAnimation(); 
      vertAnim.From = mainViewer.VerticalOffset; 
      vertAnim.To = y; 
      vertAnim.DecelerationRatio = .2; 
      vertAnim.Duration = new Duration(TimeSpan.FromMilliseconds(25000)); 
      DoubleAnimation horzAnim = new DoubleAnimation(); 
      horzAnim.From = mainViewer.HorizontalOffset; 
      horzAnim.To = x; 
      horzAnim.DecelerationRatio = .2; 
      horzAnim.Duration = new Duration(TimeSpan.FromMilliseconds(1000)); 

      sb.Children.Add(vertAnim); 
      sb.Children.Add(horzAnim); 
      Storyboard.SetTarget(vertAnim, mainViewer); 
      Storyboard.SetTargetProperty(vertAnim, new PropertyPath(AniScrollViewer.CurrentVerticalOffsetProperty)); 
      Storyboard.SetTarget(horzAnim, mainViewer); 
      Storyboard.SetTargetProperty(horzAnim, new PropertyPath(AniScrollViewer.CurrentHorizontalOffsetProperty)); 
      sb.Begin(this); 

     } 


     private void ScrollItems() 
     { 
      mainViewer.ScrollToTop(); // It does not scroll to top 
     } 

    } 

XAML

<Grid> 
     <Grid.RowDefinitions> 
      <RowDefinition Height="*"></RowDefinition> 
      <RowDefinition Height="50"></RowDefinition> 
     </Grid.RowDefinitions> 
     <local:AniScrollViewer x:Name="mainViewer" Grid.Row="0" HorizontalAlignment="Stretch" VerticalAlignment="Stretch"> 
      <StackPanel x:Name="mainContent"></StackPanel> 
     </local:AniScrollViewer> 
     <StackPanel Margin="10,10,0,10" Grid.Row="1" Orientation="Horizontal" Width="258"> 
      <ComboBox x:Name="cbJumpTo" Margin="5" Width="84.884"></ComboBox> 
      <Button x:Name="btnAnimate" Margin="5" Click="btnAnimate_Click">Start Animation</Button> 
      <Label x:Name="labelH" Content="Label"/> 
     </StackPanel> 
    </Grid> 

Answer 1

Я просто использовать этот код

private void ScrollItems() 
     { 
      ScrollToPositionTop(0,0); // It does not scroll to top 
     } 

private void ScrollToPositionTop(double x, double y) 
     { 

      DoubleAnimation vertAnim = new DoubleAnimation(); 
      vertAnim.From = mainViewer.VerticalOffset; 
      vertAnim.To = y; 
      vertAnim.DecelerationRatio = .2; 
      vertAnim.Duration = new Duration(TimeSpan.FromMilliseconds(0)); 
      DoubleAnimation horzAnim = new DoubleAnimation(); 
      horzAnim.From = mainViewer.HorizontalOffset; 
      horzAnim.To = x; 
      horzAnim.DecelerationRatio = .2; 
      horzAnim.Duration = new Duration(TimeSpan.FromMilliseconds(0)); 

      sb.Children.Add(vertAnim); 
      sb.Children.Add(horzAnim); 
      Storyboard.SetTarget(vertAnim, mainViewer); 
      Storyboard.SetTargetProperty(vertAnim, new PropertyPath(AniScrollViewer.CurrentVerticalOffsetProperty)); 
      Storyboard.SetTarget(horzAnim, mainViewer); 
      Storyboard.SetTargetProperty(horzAnim, new PropertyPath(AniScrollViewer.CurrentHorizontalOffsetProperty)); 
      sb.Begin(this); 

     }