protected override UIElement GetElementCore(ElementFactoryGetArgs args)
{
object newContent;
{
object init()
{
if (m_itemTemplateWrapper != null)
{
return(m_itemTemplateWrapper.GetElement(args));
}
return(args.Data);
}
newContent = init();
}
if (newContent is NavigationViewItemBase newItem)
{
return(newItem);
}
// Create a wrapping container for the data
var nvi = new NavigationViewItem();
nvi.Content = newContent;
return(nvi);
}
public UIElement GetElement(ElementFactoryGetArgs args)
{
var selectedTemplate = Template ?? TemplateSelector.SelectTemplate(args.Data, null);
var recyclePool = RecyclePool.GetPoolInstance(selectedTemplate);
UIElement element = null;
if (recyclePool != null)
{
// try to get an element from the recycle pool.
element = recyclePool.TryGetElement(string.Empty /* key */, args.Parent as FrameworkElement);
}
if (element == null)
{
// no element was found in recycle pool, create a new element
element = selectedTemplate.LoadContent() as FrameworkElement;
// Template returned null, so insert empty element to render nothing
if (element == null)
{
element = new Rectangle {
Width = 0,
Height = 0
};
}
// Associate template with element
element.SetValue(RecyclePool.OriginTemplateProperty, selectedTemplate);
}
return(element);
}
protected override UIElement GetElementCore(ElementFactoryGetArgs args)
{
object newContent;
if (m_itemTemplateWrapper != null)
{
newContent = m_itemTemplateWrapper.GetElement(args);
}
else
{
newContent = args.Data;
}
// Element is already a RadioButton, so we just return it.
if (newContent is RadioButton radioButton)
{
return(radioButton);
}
// Element is not a RadioButton. We'll wrap it in a RadioButton now.
var newRadioButton = new RadioButton();
newRadioButton.Content = args.Data;
// If a user provided item template exists, we pass the template down to the ContentPresenter of the RadioButton.
if (m_itemTemplateWrapper is ItemTemplateWrapper itemTemplateWrapper)
{
newRadioButton.ContentTemplate = itemTemplateWrapper.Template;
}
return(newRadioButton);
}
protected override UIElement GetElementCore(ElementFactoryGetArgs args)
{
if (args.Data is RadioButton radioButton)
{
return(radioButton);
}
else
{
var newRadioButton = new RadioButton();
newRadioButton.Content = args.Data;
return(newRadioButton);
}
}
public UIElement GetElement(ElementFactoryGetArgs args)
{
var selectedTemplate = Template ?? TemplateSelector.SelectTemplate(args.Data, null);
// Check if selected template we got is valid
if (selectedTemplate == null)
{
selectedTemplate = TemplateSelector.SelectTemplate(args.Data, null);
if (selectedTemplate == null)
{
// Still nullptr, fail with a reasonable message now.
throw new InvalidOperationException("Null encountered as data template. That is not a valid value for a data template, and can not be used.");
}
}
var recyclePool = RecyclePool.GetPoolInstance(selectedTemplate);
UIElement element = null;
if (recyclePool != null)
{
// try to get an element from the recycle pool.
element = recyclePool.TryGetElement(string.Empty /* key */, args.Parent as FrameworkElement);
}
if (element == null)
{
// no element was found in recycle pool, create a new element
element = selectedTemplate.LoadContent() as FrameworkElement;
// Template returned null, so insert empty element to render nothing
if (element == null)
{
element = new Rectangle {
Width = 0,
Height = 0
};
}
// Associate template with element
element.SetValue(RecyclePool.OriginTemplateProperty, selectedTemplate);
}
return(element);
}
protected virtual UIElement GetElementCore(ElementFactoryGetArgs args)
{
throw new NotImplementedException();
}
public UIElement GetElement(ElementFactoryGetArgs args)
{
return(GetElementCore(args));
}
// Retrieve the element that will be displayed for a specific data item.
// If the resolved element is not derived from NavigationViewItemBase, wrap in a NavigationViewItem before returning.
protected override UIElement GetElementCore(ElementFactoryGetArgs args)
{
object newContent;
{
object init()
{
if (m_itemTemplateWrapper != null)
{
return(m_itemTemplateWrapper.GetElement(args));
}
return(args.Data);
}
newContent = init();
}
// Element is already of expected type, just return it
if (newContent is NavigationViewItemBase newItem)
{
return(newItem);
}
// Get or create a wrapping container for the data
NavigationViewItem nvi;
{
nvi = init();
NavigationViewItem init()
{
if (navigationViewItemPool.Count > 0)
{
var nvi = navigationViewItemPool.Last();
navigationViewItemPool.RemoveLast();
return(nvi);
}
return(new NavigationViewItem());
}
}
var nviImpl = nvi;
nviImpl.CreatedByNavigationViewItemsFactory = true;
// If a user provided item template exists, just pass the template and data down to the ContentPresenter of the NavigationViewItem
if (m_itemTemplateWrapper != null)
{
if (m_itemTemplateWrapper is ItemTemplateWrapper itemTemplateWrapper)
{
// Recycle newContent
var tempArgs = new ElementFactoryRecycleArgs();
tempArgs.Element = newContent as UIElement;
m_itemTemplateWrapper.RecycleElement(tempArgs);
nviImpl.Content = args.Data;
nviImpl.ContentTemplate = itemTemplateWrapper.Template;
nviImpl.ContentTemplateSelector = itemTemplateWrapper.TemplateSelector;
return(nviImpl);
}
}
nviImpl.Content = newContent;
return(nviImpl);
}
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);
}
protected abstract UIElement GetElementCore(ElementFactoryGetArgs args);
