private async static void ItemsSourceChanged(object sender, EventArgs eventArgs)
{
var itemsControl = (ItemsControl)sender;
if (itemsControl.ItemsSource == null)
{
return;
}
var opacityAnimation = new DoubleAnimation(0, 1, TimeSpan.FromMilliseconds(260), FillBehavior.Stop);
var marginAnimation = new ThicknessAnimation(new Thickness(-20, 0, 20, 0), new Thickness(0),
TimeSpan.FromMilliseconds(240), FillBehavior.Stop)
{
EasingFunction = new CircleEase {
EasingMode = EasingMode.EaseOut
}
};
if (Timers.ContainsKey(itemsControl))
{
Timers[itemsControl].Stop();
Timers.Remove(itemsControl);
}
List <ListBoxItem> visibleItems;
itemsControl.Opacity = 0;
while (true)
{
visibleItems = DependencyObjectExtensions.GetVisibleItemsFromItemsControl(itemsControl,
Window.GetWindow(itemsControl));
if (visibleItems.Count > 0 || itemsControl.Items.Count == 0)
{
break;
}
await Task.Delay(1);
}
Debug.Print("Items to animate: " + visibleItems.Count);
foreach (var item in visibleItems)
{
item.Opacity = 0;
}
itemsControl.Opacity = 1;
DispatcherTimer dispatcherTimer;
var enumerator = visibleItems.GetEnumerator();
if (enumerator.MoveNext())
{
ScrollChangedEventHandler scrollChangedEventHandler = null;
scrollChangedEventHandler = (o, args) =>
{
var handler = scrollChangedEventHandler;
if (handler != null)
{
itemsControl.RemoveHandler(ScrollViewer.ScrollChangedEvent, handler);
}
if (!Timers.ContainsKey(itemsControl) || !Timers[itemsControl].IsEnabled)
{
return;
}
var timer = Timers[itemsControl];
timer.Stop();
while (true)
{
var item = enumerator.Current;
if (item == null)
{
break;
}
item.Opacity = 1;
if (!enumerator.MoveNext())
{
break;
}
}
};
dispatcherTimer = new DispatcherTimer {
Interval = TimeSpan.FromMilliseconds(30)
};
dispatcherTimer.Tick += (s, timerE) =>
{
var item = enumerator.Current;
if (item == null)
{
return;
}
item.BeginAnimation(FrameworkElement.MarginProperty, marginAnimation);
item.BeginAnimation(UIElement.OpacityProperty, opacityAnimation);
item.Opacity = 1;
if (!enumerator.MoveNext())
{
dispatcherTimer.Stop();
itemsControl.RemoveHandler(ScrollViewer.ScrollChangedEvent, scrollChangedEventHandler);
}
};
if (Timers.ContainsKey(itemsControl))
{
Timers.Remove(itemsControl);
}
Timers.Add(itemsControl, dispatcherTimer);
dispatcherTimer.Start();
itemsControl.AddHandler(ScrollViewer.ScrollChangedEvent, scrollChangedEventHandler);
}
}