/// <summary>
/// Fired when the view has changed. Update who is in and who isn't in the ViewPort.
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void UpdateWhoIsInViewPort()
{
// What is the view port in the child's cooredinates.
var viewport = new Rect(new Point(_host.HorizontalOffset, _host.VerticalOffset), new Point(_host.HorizontalOffset + _host.RenderSize.Width, _host.VerticalOffset + _host.RenderSize.Height));
// Go through everything owned by the scroll bar's panel, and set it.
// Normally a content presenter holds just one item, but a DataTemplate (or other) could have multiple,
// so we will be sure to support all children of the content presenter.
_itemContainer = (_host.Content as ItemsControl);
int itemCount = _itemContainer.Items.Count;
var inframe = from index in Enumerable.Range(0, itemCount)
let container = _itemContainer.ContainerFromIndex(index) as ContentPresenter
let inFrame = isInFrame(viewport, container)
select Tuple.Create(container, inFrame);
// We want to turn on a few for a buffer as well.
var initialList = inframe.TakeWhile(t => t.Item2 == false);
var inViewPortList = inframe.Where(t => t.Item2);
var tailList = inframe.SkipWhile(t => t.Item2 == false).Where(t => t.Item2 == false);
var nbuf = initialList.Count() - ItemsWaitingInTheWings;
if (nbuf > 0)
{
initialList = initialList.Take(nbuf)
.Concat(initialList.Skip(nbuf).Select(t => Tuple.Create(t.Item1, true)));
}
tailList =
tailList.Take(ItemsWaitingInTheWings).Select(t => Tuple.Create(t.Item1, true))
.Concat(tailList.Skip(ItemsWaitingInTheWings));
inframe = initialList.Concat(inViewPortList).Concat(tailList);
// Ok - and finally issue a "set" for all the visual elements in the scrolling view.
var allToSet = from p in inframe
let cnt = VisualTreeHelper.GetChildrenCount(p.Item1)
from childIndex in Enumerable.Range(0, cnt)
let child = VisualTreeHelper.GetChild(p.Item1, childIndex) as UIElement
where (child != null)
select Tuple.Create(child, p.Item2);
foreach (var frameInfo in allToSet)
{
_updateFunction(frameInfo.Item1, frameInfo.Item2);
}
}
public static IEnumerable <FrameworkElement> GetItemsInView(this ItemsControl itemsControl)
{
VirtualizingStackPanel vsp = GetChild <VirtualizingStackPanel>(itemsControl);
int firstVisibleItem = (int)vsp.VerticalOffset;
int visibleItemCount = (int)vsp.ViewportHeight;
for (int index = firstVisibleItem; index <= firstVisibleItem + visibleItemCount + 1; index++)
{
var item = itemsControl.ContainerFromIndex(index) as FrameworkElement;
if (item == null)
{
continue;
}
yield return(item);
}
}
public static async Task AnimateItems(this ItemsControl itemsControl, AnimationDefinition animationDefinition, double itemDelay = 0.05)
{
if (itemsControl == null)
{
return;
}
if (animationDefinition == null)
{
return;
}
if (itemDelay <= 0.0)
{
itemDelay = 0.05;
}
itemsControl.UpdateLayout();
var animations = new List <Task>();
double baseDelay = animationDefinition.Delay;
for (int index = 0; index < itemsControl.Items.Count; index++)
{
#if NETFX_CORE || WINDOWS_81_PORTABLE
var container = (FrameworkElement)itemsControl.ContainerFromIndex(index);
#endif
#if WINDOWS_PHONE
var container = (FrameworkElement)itemsControl.ItemContainerGenerator.ContainerFromIndex(index);
#endif
if (container == null)
{
continue;
}
animationDefinition.Delay = baseDelay + (itemDelay * index);
AnimationManager.ClearAnimationProperties(container);
animations.Add(
container.AnimateAsync(animationDefinition));
}
animationDefinition.Delay = baseDelay;
await Task.WhenAll(animations.ToArray());
}
public static IEnumerable <object> GetVisibleItems(ItemsControl itemsControl)
{
for (int i = 0; i < itemsControl.Items.Count; i++)
{
var obj = itemsControl.ContainerFromIndex(i) as FrameworkElement;
if (obj != null)
{
GeneralTransform gt = obj.TransformToVisual(itemsControl);
var rect = gt.TransformBounds(new Rect(0, 0, obj.ActualWidth, obj.ActualHeight));
if (rect.Bottom < 0 || rect.Top > itemsControl.ActualHeight)
{
continue;
}
yield return(itemsControl.Items[i]);
}
}
}
private static void SetShiftSteps(ItemsControl itemsControl, int steps)
{
if (itemsControl?.Items == null || steps == 0)
{
return;
}
for (int i = 0; i < itemsControl.Items?.Count; i++)
{
var container = itemsControl.ContainerFromIndex(i);
if (container == null)
{
continue;
}
var rowlist = VisualTreeHelper.GetChild(container, 0) as RRowlist;
if (rowlist == null)
{
continue;
}
rowlist.ShiftSteps = steps;
}
}
/// <summary>
/// Synchronizes the scroll offset of the target ItemsControl to the offset of the source ItemsControl
/// such that the first visible item in both controls is the same item.
/// </summary>
/// <param name="targetItemsControl">The ItemsControl whose scroll offset is to be updated.</param>
/// <param name="sourceItemsControl">The ItemsControl whose scroll offset will be matched in the target.</param>
/// <param name="throwOnFail">Specifies whether an exception should be thrown on failure.</param>
public static void SynchronizeScrollOffset(this ItemsControl targetItemsControl, ItemsControl sourceItemsControl, bool throwOnFail = false)
{
var firstVisibleIndex = sourceItemsControl.GetFirstVisibleIndex();
if (firstVisibleIndex == -1)
{
if (throwOnFail)
{
throw new InvalidOperationException();
}
return;
}
var targetListBox = targetItemsControl as ListBox;
if (targetListBox != null)
{
targetListBox.ScrollIntoView(sourceItemsControl.IndexFromContainer(sourceItemsControl.ContainerFromIndex(firstVisibleIndex)));
return;
}
var targetListViewBase = targetItemsControl as ListViewBase;
if (targetListViewBase != null)
{
targetListViewBase.ScrollIntoView(sourceItemsControl.IndexFromContainer(sourceItemsControl.ContainerFromIndex(firstVisibleIndex)), ScrollIntoViewAlignment.Leading);
return;
}
var scrollViewer = targetItemsControl.GetScrollViewer();
if (scrollViewer != null)
{
var container = (FrameworkElement)targetItemsControl.ContainerFromIndex(firstVisibleIndex);
var position = container.TransformToVisual(scrollViewer).TransformPoint(new Point());
scrollViewer.ChangeView(scrollViewer.HorizontalOffset + position.X, scrollViewer.VerticalOffset + position.Y, null);
}
}
private Collection <FrameworkElement> GetItemsToAnimate()
{
Collection <FrameworkElement> items = new Collection <FrameworkElement>();
ItemsControl itemsControl = this.containerToAnimate as ItemsControl;
if (itemsControl != null)
{
// TODO - visible items only
for (int i = 0; i < itemsControl.Items.Count; i++)
{
FrameworkElement itemToAdd = itemsControl.ContainerFromIndex(i) as FrameworkElement;
if (itemToAdd == null || !this.IsItemVisible(itemToAdd))
{
continue;
}
if (this.SequentialMode == SequentialMode.FirstToLast)
{
items.Add(itemToAdd);
}
else
{
items.Insert(0, itemToAdd);
}
}
}
else
{
if (this.containerToAnimate is IItemsContainer)
{
FrameworkElement[] viewportItems = ((IItemsContainer)this.containerToAnimate).ViewportItems;
for (int i = 0; i < viewportItems.Length; i++)
{
FrameworkElement itemToAdd = viewportItems[i];
if (this.SequentialMode == SequentialMode.FirstToLast)
{
items.Add(itemToAdd);
}
else
{
items.Insert(0, itemToAdd);
}
}
}
else if (this.containerToAnimate is Panel)
{
UIElementCollection children = (this.containerToAnimate as Panel).Children;
for (int i = 0; i < children.Count; i++)
{
FrameworkElement itemToAdd = children[i] as FrameworkElement;
if (!this.IsItemVisible(itemToAdd))
{
continue;
}
if (this.SequentialMode == SequentialMode.FirstToLast)
{
items.Add(itemToAdd);
}
else
{
items.Insert(0, itemToAdd);
}
}
}
}
return(items);
}
public static IList <WeakReference> VisibleItems(this ItemsControl itemsControl)
{
var result = new List <WeakReference>();
if (VisualTreeHelper.GetChildrenCount(itemsControl) == 0)
{
return(result);
}
var scrollHost = VisualTreeHelper.GetChild(itemsControl, 0) as ScrollViewer;
if (scrollHost == null)
{
return(result);
}
if (itemsControl.Items == null)
{
return(result);
}
itemsControl.UpdateLayout();
int index;
for (index = 0; index < itemsControl.Items.Count; index++)
{
#if NETFX_CORE || WINDOWS_81_PORTABLE
var container = (FrameworkElement)itemsControl.ContainerFromIndex(index);
#endif
#if WINDOWS_PHONE
var container = (FrameworkElement)itemsControl.ItemContainerGenerator.ContainerFromIndex(index);
#endif
if (container != null)
{
GeneralTransform itemTransform = null;
try
{
itemTransform = container.TransformToVisual(scrollHost);
}
catch (ArgumentException) // not always in visual tree
{
return(result);
}
#if NETFX_CORE || WINDOWS_81_PORTABLE
var boundingBox = new Rect(
itemTransform.TransformPoint(new Point()),
itemTransform.TransformPoint(new Point(container.ActualWidth, container.ActualHeight)));
#elif WINDOWS_PHONE
var boundingBox = new Rect(
itemTransform.Transform(new Point()),
itemTransform.Transform(new Point(container.ActualWidth, container.ActualHeight)));
#endif
if (boundingBox.Bottom > 0)
{
result.Add(new WeakReference(container));
index++;
break;
}
}
}
for (; index < itemsControl.Items.Count; index++)
{
#if NETFX_CORE || WINDOWS_81_PORTABLE
var container = (FrameworkElement)itemsControl.ContainerFromIndex(index);
#endif
#if WINDOWS_PHONE
var container = (FrameworkElement)itemsControl.ItemContainerGenerator.ContainerFromIndex(index);
#endif
GeneralTransform itemTransform = null;
try
{
itemTransform = container.TransformToVisual(scrollHost);
}
catch (ArgumentException) // not always in visual tree
{
return(result);
}
#if NETFX_CORE || WINDOWS_81_PORTABLE
var boundingBox = new Rect(
itemTransform.TransformPoint(new Point()),
itemTransform.TransformPoint(new Point(container.ActualWidth, container.ActualHeight)));
#elif WINDOWS_PHONE
var boundingBox = new Rect(
itemTransform.Transform(new Point()),
itemTransform.Transform(new Point(container.ActualWidth, container.ActualHeight)));
#endif
if (boundingBox.Top >= scrollHost.ActualHeight)
{
break;
}
result.Add(new WeakReference(container));
}
return(result);
}
