public void UpdatePin(UIElement element, bool addPin)
{
var parent = CachedVisualTreeHelpers.GetParent(element);
DependencyObject child = element;
while (parent != null)
{
if (parent is ItemsRepeater repeater)
{
var virtInfo = ItemsRepeater.GetVirtualizationInfo((UIElement)child);
if (virtInfo.IsRealized)
{
if (addPin)
{
virtInfo.AddPin();
}
else if (virtInfo.IsPinned)
{
if (virtInfo.RemovePin() == 0)
{
// ElementFactory is invoked during the measure pass.
// We will clear the element then.
repeater.InvalidateMeasure();
}
}
}
}
child = parent;
parent = CachedVisualTreeHelpers.GetParent(child);
}
}
private void OnHideAnimationCompleted(ElementAnimator sender, UIElement element)
{
if (CachedVisualTreeHelpers.GetParent(element) == m_owner)
{
m_owner.ViewManager.ClearElementToElementFactory(element);
// Invalidate arrange so that repeater can arrange this element off-screen.
m_owner.InvalidateArrange();
}
}
private void UpdateFocusedElement()
{
UIElement focusedElement = null;
// auto child = winrt::FocusManager::GetFocusedElement().as<winrt::DependencyObject>();
var child = Keyboard.FocusedElement as DependencyObject;
if (child != null)
{
var parent = CachedVisualTreeHelpers.GetParent(child);
var owner = m_owner;
// Find out if the focused element belongs to one of our direct
// children.
while (parent != null)
{
var repeater = parent as ItemsRepeater;
if (repeater != null)
{
var element = child as UIElement;
if (repeater == owner && ItemsRepeater.GetVirtualizationInfo(element).IsRealized)
{
focusedElement = element;
}
break;
}
child = parent;
parent = CachedVisualTreeHelpers.GetParent(child);
}
}
// If the focused element has changed,
// we need to unpin the old one and pin the new one.
if (m_lastFocusedElement != focusedElement)
{
if (m_lastFocusedElement != null)
{
UpdatePin(m_lastFocusedElement, false /* addPin */);
}
if (focusedElement != null)
{
UpdatePin(focusedElement, true /* addPin */);
}
m_lastFocusedElement = (focusedElement);
}
}
protected override Size ArrangeOverride(Size finalSize)
{
if (m_isLayoutInProgress)
{
throw new Exception("Reentrancy detected during layout.");
}
if (IsProcessingCollectionChange)
{
throw new Exception("Cannot run layout in the middle of a collection change.");
}
m_isLayoutInProgress = true;
try
{
Size arrangeSize = default;
if (Layout is Layout layout)
{
arrangeSize = layout.Arrange(GetLayoutContext(), finalSize);
}
// The view manager might clear elements during this call.
// That's why we call it before arranging cleared elements
// off screen.
ViewManager.OnOwnerArranged();
var children = Children;
for (int i = 0; i < children.Count; ++i)
{
var element = children[i];
var virtInfo = GetVirtualizationInfo(element);
virtInfo.KeepAlive = false;
if (virtInfo.Owner == ElementOwner.ElementFactory ||
virtInfo.Owner == ElementOwner.PinnedPool)
{
// Toss it away. And arrange it with size 0 so that XYFocus won't use it.
element.Arrange(new Rect(
ClearedElementsArrangePosition.X - element.DesiredSize.Width,
ClearedElementsArrangePosition.Y - element.DesiredSize.Height,
0.0,
0.0));
}
else
{
var newBounds = CachedVisualTreeHelpers.GetLayoutSlot(element as FrameworkElement);
if (virtInfo.ArrangeBounds != InvalidRect &&
newBounds != virtInfo.ArrangeBounds)
{
AnimationManager.OnElementBoundsChanged(element, virtInfo.ArrangeBounds, newBounds);
}
virtInfo.ArrangeBounds = newBounds;
}
}
m_viewportManager.OnOwnerArranged();
AnimationManager.OnOwnerArranged();
return(arrangeSize);
}
finally
{
m_isLayoutInProgress = false;
}
}
private UIElement GetElementFromElementFactory(int index)
{
// The view generator is the provider of last resort.
var data = m_owner.ItemsSourceView.GetAt(index);
UIElement initElement()
{
var providedElementFactory = m_owner.ItemTemplateShim;
if (providedElementFactory == null)
{
if (data is UIElement dataAsElement)
{
return(dataAsElement);
}
}
IElementFactoryShim initElementFactory()
{
if (providedElementFactory == null)
{
var factory = XamlReader.Parse("<DataTemplate xmlns='http://schemas.microsoft.com/winfx/2006/xaml/presentation'><TextBlock Text='{Binding}'/></DataTemplate>") as DataTemplate;
m_owner.ItemTemplate = factory;
return(m_owner.ItemTemplateShim);
}
return(providedElementFactory);
}
var elementFactory = initElementFactory();
ElementFactoryGetArgs initArgs()
{
if (m_ElementFactoryGetArgs == null)
{
m_ElementFactoryGetArgs = new ElementFactoryGetArgs();
}
return(m_ElementFactoryGetArgs);
}
var args = initArgs();
try
{
args.Data = data;
args.Parent = m_owner;
args.Index = index;
return(elementFactory.GetElement(args));
}
finally
{
args.Data = null;
args.Parent = null;
}
}
var element = initElement();
var virtInfo = ItemsRepeater.TryGetVirtualizationInfo(element);
if (virtInfo == null)
{
virtInfo = ItemsRepeater.CreateAndInitializeVirtualizationInfo(element);
}
else
{
// View obtained from ElementFactory already has a VirtualizationInfo attached to it
// which means that the element has been recycled and not created from scratch.
}
if (data != element)
{
if (element is FrameworkElement elementAsFE)
{
// Set data context only if no x:Bind was used. ie. No data template component on the root.
// If the passed in data is a UIElement and is different from the element returned by
// the template factory then we need to propagate the DataContext.
// Otherwise just set the DataContext on the element as the data.
object initElementDataContext()
{
if (data is FrameworkElement dataAsElement)
{
var dataDataContext = dataAsElement.DataContext;
if (dataDataContext != null)
{
return(dataDataContext);
}
}
return(data);
}
var elementDataContext = initElementDataContext();
elementAsFE.DataContext = elementDataContext;
}
else
{
Debug.Assert(false, "Element returned by factory is not a FrameworkElement!");
}
}
virtInfo.MoveOwnershipToLayoutFromElementFactory(
index,
/* uniqueId: */
m_owner.ItemsSourceView.HasKeyIndexMapping ?
m_owner.ItemsSourceView.KeyFromIndex(index) :
string.Empty);
// The view generator is the only provider that prepares the element.
var repeater = m_owner;
// Add the element to the children collection here before raising OnElementPrepared so
// that handlers can walk up the tree in case they want to find their IndexPath in the
// nested case.
var children = repeater.Children;
if (CachedVisualTreeHelpers.GetParent(element) != repeater)
{
children.Add(element);
}
repeater.AnimationManager.OnElementPrepared(element);
repeater.OnElementPrepared(element, index);
// Update realized indices
m_firstRealizedElementIndexHeldByLayout = Math.Min(m_firstRealizedElementIndexHeldByLayout, index);
m_lastRealizedElementIndexHeldByLayout = Math.Max(m_lastRealizedElementIndexHeldByLayout, index);
return(element);
}
private UIElement GetElementFromElementFactory(int index)
{
// The view generator is the provider of last resort.
var data = m_owner.ItemsSourceView.GetAt(index);
var itemTemplateFactory = m_owner.ItemTemplateShim;
UIElement element = null;
bool itemsSourceContainsElements = false;
if (itemTemplateFactory == null)
{
element = data as UIElement;
// No item template provided and ItemsSource contains objects derived from UIElement.
// In this case, just use the data directly as elements.
itemsSourceContainsElements = element != null;
}
if (element == null)
{
if (itemTemplateFactory == null)
{
// If no ItemTemplate was provided, use a default
var factory = XamlReader.Parse("<DataTemplate xmlns='http://schemas.microsoft.com/winfx/2006/xaml/presentation'><TextBlock Text='{Binding}'/></DataTemplate>") as DataTemplate;
m_owner.ItemTemplate = factory;
itemTemplateFactory = m_owner.ItemTemplateShim;
}
if (m_ElementFactoryGetArgs == null)
{
// Create one.
m_ElementFactoryGetArgs = new ElementFactoryGetArgs();
}
var args = m_ElementFactoryGetArgs;
args.Data = data;
args.Parent = m_owner;
args.Index = index;
element = itemTemplateFactory.GetElement(args);
args.Data = null;
args.Parent = null;
}
var virtInfo = ItemsRepeater.TryGetVirtualizationInfo(element);
if (virtInfo == null)
{
virtInfo = ItemsRepeater.CreateAndInitializeVirtualizationInfo(element);
}
else
{
// View obtained from ElementFactory already has a VirtualizationInfo attached to it
// which means that the element has been recycled and not created from scratch.
}
if (!itemsSourceContainsElements)
{
// Set data context only if no x:Bind was used. ie. No data template component on the root.
var elementAsFE = element as FrameworkElement;
elementAsFE.DataContext = data;
}
virtInfo.MoveOwnershipToLayoutFromElementFactory(
index,
/* uniqueId: */
m_owner.ItemsSourceView.HasKeyIndexMapping ?
m_owner.ItemsSourceView.KeyFromIndex(index) :
string.Empty);
// The view generator is the only provider that prepares the element.
var repeater = m_owner;
// Add the element to the children collection here before raising OnElementPrepared so
// that handlers can walk up the tree in case they want to find their IndexPath in the
// nested case.
var children = repeater.Children;
if (CachedVisualTreeHelpers.GetParent(element) != repeater)
{
children.Add(element);
}
repeater.AnimationManager.OnElementPrepared(element);
repeater.OnElementPrepared(element, index);
// Update realized indices
m_firstRealizedElementIndexHeldByLayout = Math.Min(m_firstRealizedElementIndexHeldByLayout, index);
m_lastRealizedElementIndexHeldByLayout = Math.Max(m_lastRealizedElementIndexHeldByLayout, index);
return(element);
}
