滾動動畫

Question

如何爲ListBox的滾動設置動畫效果？我知道我可以使用scrollIntoView，但我怎麼能動畫它？我想按箭頭鍵從一個listBoxItem移動到另一個。

Answer 1

這是基於同樣的方法，因爲下面的鏈接
http://aniscrollviewer.codeplex.com/

的VerticalOffset屬性爲只讀，因此，你可以在ScrollViewer這又確實ScrollToVerticalOffset使用附加屬性VerticalOffset一個粗略的實現。這個附屬的屬性可以是動畫的。

您還可以爲ItemsControl創建名爲AnimateScrollIntoView的擴展方法。

這樣稱呼它

listBox.AnimateScrollIntoView(yourItem); 

ScrollViewerBehavior

public class ScrollViewerBehavior 
{ 
    public static DependencyProperty VerticalOffsetProperty = 
     DependencyProperty.RegisterAttached("VerticalOffset", 
              typeof(double), 
              typeof(ScrollViewerBehavior), 
              new UIPropertyMetadata(0.0, OnVerticalOffsetChanged)); 

    public static void SetVerticalOffset(FrameworkElement target, double value) 
    { 
     target.SetValue(VerticalOffsetProperty, value); 
    } 
    public static double GetVerticalOffset(FrameworkElement target) 
    { 
     return (double)target.GetValue(VerticalOffsetProperty); 
    } 
    private static void OnVerticalOffsetChanged(DependencyObject target, DependencyPropertyChangedEventArgs e) 
    { 
     ScrollViewer scrollViewer = target as ScrollViewer; 
     if (scrollViewer != null) 
     { 
      scrollViewer.ScrollToVerticalOffset((double)e.NewValue); 
     } 
    } 
} 

ItemsControlExtensions

public static class ItemsControlExtensions 
{ 
    public static void AnimateScrollIntoView(this ItemsControl itemsControl, object item) 
    { 
     ScrollViewer scrollViewer = VisualTreeHelpers.GetVisualChild<ScrollViewer>(itemsControl); 

     UIElement container = itemsControl.ItemContainerGenerator.ContainerFromItem(item) as UIElement; 
     int index = itemsControl.ItemContainerGenerator.IndexFromContainer(container); 
     double toValue = scrollViewer.ScrollableHeight * ((double)index/itemsControl.Items.Count); 
     Point relativePoint = container.TranslatePoint(new Point(0.0, 0.0), Window.GetWindow(container)); 

     DoubleAnimation verticalAnimation = new DoubleAnimation(); 
     verticalAnimation.From = scrollViewer.VerticalOffset; 
     verticalAnimation.To = toValue; 
     verticalAnimation.DecelerationRatio = .2; 
     verticalAnimation.Duration = new Duration(TimeSpan.FromMilliseconds(1000)); 
     Storyboard storyboard = new Storyboard(); 
     storyboard.Children.Add(verticalAnimation); 
     Storyboard.SetTarget(verticalAnimation, scrollViewer); 
     Storyboard.SetTargetProperty(verticalAnimation, new PropertyPath(ScrollViewerBehavior.VerticalOffsetProperty)); 
     storyboard.Begin(); 
    } 
} 

而且因爲你還需要得到0123的舉行你需要這個

public static class VisualTreeHelpers 
{ 
    public static T GetVisualChild<T>(DependencyObject parent) where T : Visual 
    { 
     T child = default(T); 

     int numVisuals = VisualTreeHelper.GetChildrenCount(parent); 
     for (int i = 0; i < numVisuals; i++) 
     { 
      Visual v = (Visual)VisualTreeHelper.GetChild(parent, i); 
      child = v as T; 
      if (child == null) 
      { 
       child = GetVisualChild<T>(v); 
      } 
      if (child != null) 
      { 
       break; 
      } 
     } 
     return child; 
    } 
} 

Answer 2

看看這article，它解釋瞭如何動畫滾動和添加觸摸手勢。在頁面底部下載源代碼並查看WpfScrollContent解決方案。我將擴展WPF列表框並將滾動動畫添加到它，以便您可以重新使用該控件。