private static void FrameworkElement_Loaded(object sender, RoutedEventArgs re)
{
var el = sender as FrameworkElement;
// locate the pivot control that this list is within
Pivot pivot = el.Ancestors <Pivot>().Single() as Pivot;
// and its index within the pivot
int pivotIndex = pivot.Items.IndexOf(el.Ancestors <PivotItem>().Single());
bool selectionChanged = false;
pivot.SelectionChanged += (s, e) => selectionChanged = true;
// handle manipulation events which occur when the user moves between pivot items
pivot.ManipulationCompleted += (s, e) =>
{
if (!selectionChanged)
{
return;
}
selectionChanged = false;
if (pivotIndex != pivot.SelectedIndex)
{
return;
}
// determine which direction this tab will be scrolling in from
bool fromRight = e.TotalManipulation.Translation.X <= 0;
// locate the stack panel that hosts the items
VirtualizingStackPanel vsp = el.Descendants <VirtualizingStackPanel>().First() as VirtualizingStackPanel;
// iterate over each of the items in view
int firstVisibleItem = (int)vsp.VerticalOffset;
int visibleItemCount = (int)vsp.ViewportHeight + 1; // overestimate by one to account for a LongListSelector header
var generator = vsp.ItemContainerGenerator.GetItemContainerGeneratorForPanel(vsp);
var AnimatedElements = vsp.Children
.Where(c =>
{
var i = generator.IndexFromContainer(c);
return(i >= firstVisibleItem && i <= firstVisibleItem + visibleItemCount);
})
.SelectMany(v => v.Descendants().Where(p => ListInertia.GetIndentLevel(p) > -1))
.ToList();
//System.Diagnostics.Debug.WriteLine(string.Format("Animating {0} items starting with {1} which consists of {2} animated elements", visibleItemCount, firstVisibleItem, AnimatedElements.Count));
vsp.Dispatcher.BeginInvoke(() =>
{
foreach (var a in AnimatedElements.SelectMany(target => GetAnimations(target as FrameworkElement, fromRight)))
{
a.Begin();
}
});
};
}
/// <summary>
/// Creates a necessary storyboards for animation. All elements receive a TranslateTransform animation. Level 0 elements also have an opacity animation.
/// </summary>
private static Storyboard[] GetAnimations(FrameworkElement element, bool fromRight)
{
int level = ListInertia.GetIndentLevel(element);
double delay = 0.4;
double from = (fromRight ? 35 : -35) * (level + 1);
element.RenderTransform = new TranslateTransform()
{
X = from
};
double duration = 0.6;
var SlideSB = new Storyboard()
{
BeginTime = TimeSpan.FromSeconds(delay),
Duration = TimeSpan.FromSeconds(duration),
};
var SlideDA = new DoubleAnimation()
{
//EasingFunction = new PowerEase() { Power = 3, EasingMode = EasingMode.EaseOut },// - level },
EasingFunction = new CircleEase()
{
EasingMode = System.Windows.Media.Animation.EasingMode.EaseOut
},
From = from,
To = 0,
Duration = TimeSpan.FromSeconds(duration),
};
if (level == 0)
{
SlideDA.EasingFunction = new PowerEase()
{
Power = 4.0,
EasingMode = System.Windows.Media.Animation.EasingMode.EaseOut
}
}
;
SlideSB.Children.Add(SlideDA);
Storyboard.SetTarget(SlideDA, element.RenderTransform);
Storyboard.SetTargetProperty(SlideDA, new PropertyPath("X"));
var FadeSB = new Storyboard()
{
Duration = TimeSpan.FromSeconds(0.35),
};
var FadeDA = new DoubleAnimation()
{
EasingFunction = new QuarticEase()
{
EasingMode = EasingMode.EaseIn
},
From = level == 0 ? 0 : 0.4,
To = 1,
Duration = FadeSB.Duration,
};
FadeSB.Children.Add(FadeDA);
Storyboard.SetTarget(FadeDA, element);
Storyboard.SetTargetProperty(FadeDA, new PropertyPath(UIElement.OpacityProperty));
return(new Storyboard[] { SlideSB, FadeSB });
}
}
