对于那些从谷歌那里得到的人 Anatoliy 的代码有效，但在鼠标滚轮滚动方面存在一些问题。
Scrolling without Fix（请记住，我正在尝试快速滚动到底部）
Scrolling with Fix
(自插，你可以查一下这个应用是什么结束Here)
让我们来看看为什么。
#region ScrollViewerPreviewMouseWheel Event Handler
private static void ScrollViewerPreviewMouseWheel(object sender, MouseWheelEventArgs e)
{
double mouseWheelChange = (double)e.Delta;
ScrollViewer scroller = (ScrollViewer)sender;
double newVOffset = GetVerticalOffset(scroller) - (mouseWheelChange / 3);
if (newVOffset < 0)
{
AnimateScroll(scroller, 0);
}
else if (newVOffset > scroller.ScrollableHeight)
{
AnimateScroll(scroller, scroller.ScrollableHeight);
}
else
{
AnimateScroll(scroller, newVOffset);
}
e.Handled = true;
}
在此处理程序代码中，您会注意到每次滚动鼠标滚轮时都会调用它。因此，当您通过快速滚动点击它时，动画没有时间完成，并且您试图从动画中间的位置滚动时被卡住了。这会在尝试更快滚动时导致抖动缓慢的滚动。
这里还有他们的代码：
private static void AnimateScroll(ScrollViewer scrollViewer, double ToValue)
{
DoubleAnimation verticalAnimation = new DoubleAnimation();
verticalAnimation.From = scrollViewer.VerticalOffset;
verticalAnimation.To = ToValue;
verticalAnimation.Duration = new Duration(GetTimeDuration(scrollViewer));
Storyboard storyboard = new Storyboard();
storyboard.Children.Add(verticalAnimation);
Storyboard.SetTarget(verticalAnimation, scrollViewer);
Storyboard.SetTargetProperty(verticalAnimation, new PropertyPath(ScrollAnimationBehavior.VerticalOffsetProperty));
storyboard.Begin();
}
有不需要的情节提要实现，可以将其移除以使滚动动画可中断，这是我们需要为了平滑快速滚动而需要的。
我们将在他们的代码顶部添加一个新变量。
public static class ScrollAnimationBehavior
{
public static double intendedLocation = 0;
...
我们需要保存动画的预期位置，这样如果我们再次调用滚动事件，我们可以在开始下一个动画调用之前立即跳转到该位置。
现在我们还需要改变一些东西。当用户使用 keydown 事件之一（向上翻页或向下翻页）或使用鼠标手动移动滚动条时，需要更新预期位置。
所以我们需要添加另一个事件来处理scrollviewer上的鼠标左键向上，并且当鼠标被抬起（放在预期位置）时，我们可以更改预期位置，以便滚轮获得更新的位置.
private static void SetEventHandlersForScrollViewer(ScrollViewer scroller)
{
scroller.PreviewMouseWheel += new MouseWheelEventHandler(ScrollViewerPreviewMouseWheel);
scroller.PreviewKeyDown += new KeyEventHandler(ScrollViewerPreviewKeyDown);
scroller.PreviewMouseLeftButtonUp += Scroller_PreviewMouseLeftButtonUp;
}
private static void Scroller_PreviewMouseLeftButtonUp(object sender, MouseButtonEventArgs e)
{
intendedLocation = ((ScrollViewer)sender).VerticalOffset;
}
我们仍然需要更新向上翻页和向下翻页区域。
private static void ScrollViewerPreviewKeyDown(object sender, KeyEventArgs e)
{
ScrollViewer scroller = (ScrollViewer)sender;
Key keyPressed = e.Key;
double newVerticalPos = GetVerticalOffset(scroller);
bool isKeyHandled = false;
if (keyPressed == Key.Down)
{
newVerticalPos = NormalizeScrollPos(scroller, (newVerticalPos + GetPointsToScroll(scroller)), Orientation.Vertical);
intendedLocation = newVerticalPos;
isKeyHandled = true;
}
else if (keyPressed == Key.PageDown)
{
newVerticalPos = NormalizeScrollPos(scroller, (newVerticalPos + scroller.ViewportHeight), Orientation.Vertical);
intendedLocation = newVerticalPos;
isKeyHandled = true;
}
else if (keyPressed == Key.Up)
{
newVerticalPos = NormalizeScrollPos(scroller, (newVerticalPos - GetPointsToScroll(scroller)), Orientation.Vertical);
intendedLocation = newVerticalPos;
isKeyHandled = true;
}
else if (keyPressed == Key.PageUp)
{
newVerticalPos = NormalizeScrollPos(scroller, (newVerticalPos - scroller.ViewportHeight), Orientation.Vertical);
intendedLocation = newVerticalPos;
isKeyHandled = true;
}
if (newVerticalPos != GetVerticalOffset(scroller))
{
intendedLocation = newVerticalPos;
AnimateScroll(scroller, newVerticalPos);
}
e.Handled = isKeyHandled;
}
现在我们已经处理了非鼠标滚轮事件来更新预期位置，让我们修复鼠标滚轮事件。
private static void ScrollViewerPreviewMouseWheel(object sender, MouseWheelEventArgs e)
{
double mouseWheelChange = (double)e.Delta;
ScrollViewer scroller = (ScrollViewer)sender;
double newVOffset = intendedLocation - (mouseWheelChange * 2);
//Incase we got hit by the mouse again. jump to the offset.
scroller.ScrollToVerticalOffset(intendedLocation);
if (newVOffset < 0)
{
newVOffset = 0;
}
if (newVOffset > scroller.ScrollableHeight)
{
newVOffset = scroller.ScrollableHeight;
}
AnimateScroll(scroller, newVOffset);
intendedLocation = newVOffset;
e.Handled = true;
}
所以变化如下
将 newVOffset 更改为根据预期位置和 mouseWheelChange 运行。
当 newVOffset 超过或低于可接受的边界时清除。
我们跳到了预期的位置，它是由最后一个滚轮事件创建的，带有它想去的地方。
如果你想改变滚动的“速度”，只需改变
double newVOffset = intendedLocation - (mouseWheelChange * 2);
您可以将修饰符从 2 倍更改为 5 倍以加快速度或将 1 倍更改为较慢。
现在处理完所有事件，让我们让动画自行取消，所以这一切都有意义。
private static void AnimateScroll(ScrollViewer scrollViewer, double ToValue)
{
scrollViewer.BeginAnimation(VerticalOffsetProperty, null);
DoubleAnimation verticalAnimation = new DoubleAnimation();
verticalAnimation.From = scrollViewer.VerticalOffset;
verticalAnimation.To = ToValue;
verticalAnimation.Duration = new Duration(GetTimeDuration(scrollViewer));
scrollViewer.BeginAnimation(VerticalOffsetProperty, verticalAnimation);
}
所以我们在这里所做的是删除故事板，并取消任何现有动画，以便我们可以从一个新的开始。
以下是完整代码（按原样提供），以防您懒得更改它，就像我只是复制它一样。
using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Media.Animation;
using System.Windows.Input;
using ScrollAnimateBehavior.Helpers;
namespace ScrollAnimateBehavior.AttachedBehaviors
{
public static class ScrollAnimationBehavior
{
public static double intendedLocation = 0;
#region Private ScrollViewer for ListBox
private static ScrollViewer _listBoxScroller = new ScrollViewer();
#endregion
#region VerticalOffset Property
public static DependencyProperty VerticalOffsetProperty =
DependencyProperty.RegisterAttached("VerticalOffset",
typeof(double),
typeof(ScrollAnimationBehavior),
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);
}
#endregion
#region TimeDuration Property
public static DependencyProperty TimeDurationProperty =
DependencyProperty.RegisterAttached("TimeDuration",
typeof(TimeSpan),
typeof(ScrollAnimationBehavior),
new PropertyMetadata(new TimeSpan(0, 0, 0, 0, 0)));
public static void SetTimeDuration(FrameworkElement target, TimeSpan value)
{
target.SetValue(TimeDurationProperty, value);
}
public static TimeSpan GetTimeDuration(FrameworkElement target)
{
return (TimeSpan)target.GetValue(TimeDurationProperty);
}
#endregion
#region PointsToScroll Property
public static DependencyProperty PointsToScrollProperty =
DependencyProperty.RegisterAttached("PointsToScroll",
typeof(double),
typeof(ScrollAnimationBehavior),
new PropertyMetadata(0.0));
public static void SetPointsToScroll(FrameworkElement target, double value)
{
target.SetValue(PointsToScrollProperty, value);
}
public static double GetPointsToScroll(FrameworkElement target)
{
return (double)target.GetValue(PointsToScrollProperty);
}
#endregion
#region OnVerticalOffset Changed
private static void OnVerticalOffsetChanged(DependencyObject target, DependencyPropertyChangedEventArgs e)
{
ScrollViewer scrollViewer = target as ScrollViewer;
if (scrollViewer != null)
{
scrollViewer.ScrollToVerticalOffset((double)e.NewValue);
}
}
#endregion
#region IsEnabled Property
public static DependencyProperty IsEnabledProperty =
DependencyProperty.RegisterAttached("IsEnabled",
typeof(bool),
typeof(ScrollAnimationBehavior),
new UIPropertyMetadata(false, OnIsEnabledChanged));
public static void SetIsEnabled(FrameworkElement target, bool value)
{
target.SetValue(IsEnabledProperty, value);
}
public static bool GetIsEnabled(FrameworkElement target)
{
return (bool)target.GetValue(IsEnabledProperty);
}
#endregion
#region OnIsEnabledChanged Changed
private static void OnIsEnabledChanged(DependencyObject sender, DependencyPropertyChangedEventArgs e)
{
var target = sender;
if (target != null && target is ScrollViewer)
{
ScrollViewer scroller = target as ScrollViewer;
scroller.Loaded += new RoutedEventHandler(scrollerLoaded);
}
if (target != null && target is ListBox)
{
ListBox listbox = target as ListBox;
listbox.Loaded += new RoutedEventHandler(listboxLoaded);
}
}
#endregion
#region AnimateScroll Helper
private static void AnimateScroll(ScrollViewer scrollViewer, double ToValue)
{
scrollViewer.BeginAnimation(VerticalOffsetProperty, null);
DoubleAnimation verticalAnimation = new DoubleAnimation();
verticalAnimation.From = scrollViewer.VerticalOffset;
verticalAnimation.To = ToValue;
verticalAnimation.Duration = new Duration(GetTimeDuration(scrollViewer));
scrollViewer.BeginAnimation(VerticalOffsetProperty, verticalAnimation);
}
#endregion
#region NormalizeScrollPos Helper
private static double NormalizeScrollPos(ScrollViewer scroll, double scrollChange, Orientation o)
{
double returnValue = scrollChange;
if (scrollChange < 0)
{
returnValue = 0;
}
if (o == Orientation.Vertical && scrollChange > scroll.ScrollableHeight)
{
returnValue = scroll.ScrollableHeight;
}
else if (o == Orientation.Horizontal && scrollChange > scroll.ScrollableWidth)
{
returnValue = scroll.ScrollableWidth;
}
return returnValue;
}
#endregion
#region UpdateScrollPosition Helper
private static void UpdateScrollPosition(object sender)
{
ListBox listbox = sender as ListBox;
if (listbox != null)
{
double scrollTo = 0;
for (int i = 0; i < (listbox.SelectedIndex); i++)
{
ListBoxItem tempItem = listbox.ItemContainerGenerator.ContainerFromItem(listbox.Items[i]) as ListBoxItem;
if (tempItem != null)
{
scrollTo += tempItem.ActualHeight;
}
}
AnimateScroll(_listBoxScroller, scrollTo);
}
}
#endregion
#region SetEventHandlersForScrollViewer Helper
private static void SetEventHandlersForScrollViewer(ScrollViewer scroller)
{
scroller.PreviewMouseWheel += new MouseWheelEventHandler(ScrollViewerPreviewMouseWheel);
scroller.PreviewKeyDown += new KeyEventHandler(ScrollViewerPreviewKeyDown);
scroller.PreviewMouseLeftButtonUp += Scroller_PreviewMouseLeftButtonUp;
}
private static void Scroller_PreviewMouseLeftButtonUp(object sender, MouseButtonEventArgs e)
{
intendedLocation = ((ScrollViewer)sender).VerticalOffset;
}
#endregion
#region scrollerLoaded Event Handler
private static void scrollerLoaded(object sender, RoutedEventArgs e)
{
ScrollViewer scroller = sender as ScrollViewer;
SetEventHandlersForScrollViewer(scroller);
}
#endregion
#region listboxLoaded Event Handler
private static void listboxLoaded(object sender, RoutedEventArgs e)
{
ListBox listbox = sender as ListBox;
_listBoxScroller = FindVisualChildHelper.GetFirstChildOfType<ScrollViewer>(listbox);
SetEventHandlersForScrollViewer(_listBoxScroller);
SetTimeDuration(_listBoxScroller, new TimeSpan(0, 0, 0, 0, 200));
SetPointsToScroll(_listBoxScroller, 16.0);
listbox.SelectionChanged += new SelectionChangedEventHandler(ListBoxSelectionChanged);
listbox.Loaded += new RoutedEventHandler(ListBoxLoaded);
listbox.LayoutUpdated += new EventHandler(ListBoxLayoutUpdated);
}
#endregion
#region ScrollViewerPreviewMouseWheel Event Handler
private static void ScrollViewerPreviewMouseWheel(object sender, MouseWheelEventArgs e)
{
double mouseWheelChange = (double)e.Delta;
ScrollViewer scroller = (ScrollViewer)sender;
double newVOffset = intendedLocation - (mouseWheelChange * 2);
//We got hit by the mouse again. jump to the offset.
scroller.ScrollToVerticalOffset(intendedLocation);
if (newVOffset < 0)
{
newVOffset = 0;
}
if (newVOffset > scroller.ScrollableHeight)
{
newVOffset = scroller.ScrollableHeight;
}
AnimateScroll(scroller, newVOffset);
intendedLocation = newVOffset;
e.Handled = true;
}
#endregion
#region ScrollViewerPreviewKeyDown Handler
private static void ScrollViewerPreviewKeyDown(object sender, KeyEventArgs e)
{
ScrollViewer scroller = (ScrollViewer)sender;
Key keyPressed = e.Key;
double newVerticalPos = GetVerticalOffset(scroller);
bool isKeyHandled = false;
if (keyPressed == Key.Down)
{
newVerticalPos = NormalizeScrollPos(scroller, (newVerticalPos + GetPointsToScroll(scroller)), Orientation.Vertical);
intendedLocation = newVerticalPos;
isKeyHandled = true;
}
else if (keyPressed == Key.PageDown)
{
newVerticalPos = NormalizeScrollPos(scroller, (newVerticalPos + scroller.ViewportHeight), Orientation.Vertical);
intendedLocation = newVerticalPos;
isKeyHandled = true;
}
else if (keyPressed == Key.Up)
{
newVerticalPos = NormalizeScrollPos(scroller, (newVerticalPos - GetPointsToScroll(scroller)), Orientation.Vertical);
intendedLocation = newVerticalPos;
isKeyHandled = true;
}
else if (keyPressed == Key.PageUp)
{
newVerticalPos = NormalizeScrollPos(scroller, (newVerticalPos - scroller.ViewportHeight), Orientation.Vertical);
intendedLocation = newVerticalPos;
isKeyHandled = true;
}
if (newVerticalPos != GetVerticalOffset(scroller))
{
intendedLocation = newVerticalPos;
AnimateScroll(scroller, newVerticalPos);
}
e.Handled = isKeyHandled;
}
#endregion
#region ListBox Event Handlers
private static void ListBoxLayoutUpdated(object sender, EventArgs e)
{
UpdateScrollPosition(sender);
}
private static void ListBoxLoaded(object sender, RoutedEventArgs e)
{
UpdateScrollPosition(sender);
}
private static void ListBoxSelectionChanged(object sender, SelectionChangedEventArgs e)
{
UpdateScrollPosition(sender);
}
#endregion
}
}