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);
}