protected void UpdatePreparedItems()
{
bool doSetItems;
bool doSetChildren;
ItemCollection preparedItems;
ItemCollection preparedChildren;
lock (_renderLock)
{
if (!_setItems && !_setChildren)
{
return;
}
doSetItems = _setItems;
_setItems = false;
doSetChildren = _setChildren;
_setChildren = false;
preparedItems = _preparedItems;
_preparedItems = null;
preparedChildren = _preparedChildren;
_preparedChildren = null;
}
Panel itemsHostPanel = _itemsHostPanel;
if (doSetChildren)
{
FrameworkElementCollection children = itemsHostPanel.Children;
lock (children.SyncRoot)
{
children.Clear(false);
if (preparedChildren != null)
{
IList <FrameworkElement> tempItems = new List <FrameworkElement>(preparedChildren.Count);
foreach (object item in preparedChildren.ExtractElements())
{
FrameworkElement fe = item as FrameworkElement;
if (fe == null)
{
MPF.TryCleanupAndDispose(item);
continue;
}
ISelectableItemContainer sic = item as ISelectableItemContainer;
if (sic != null && sic.Selected)
{
_lastSelectedItem = sic;
}
tempItems.Add(fe);
}
children.AddAll(tempItems);
preparedChildren.Dispose();
}
}
}
if (doSetItems)
{
_items.Clear();
if (preparedItems != null)
{
_items.AddAll(preparedItems.ExtractElements());
preparedItems.Dispose();
}
}
var vsp = itemsHostPanel as IVirtualizingPanel;
if (vsp == null)
{
IsEmpty = itemsHostPanel.Children.Count == 0;
}
// else IsEmpty has been updated by PrepareItemsOverride
}
protected virtual void PrepareItemsOverride(bool force)
{
if (_panelTemplateApplied && _itemsHostPanel != null && !force)
{
return;
}
// Check properties which are necessary in each case
if (ItemsPanel == null)
{
return;
}
ItemsPresenter presenter = FindItemsPresenter();
if (presenter == null)
{
return;
}
if (!_panelTemplateApplied)
{
_panelTemplateApplied = true;
presenter.ApplyTemplate(ItemsPanel);
_itemsHostPanel = null;
}
if (_itemsHostPanel == null)
{
_itemsHostPanel = presenter.ItemsHostPanel;
}
if (_itemsHostPanel == null)
{
return;
}
// Albert: We cannot exit the method if one of the styles is not set because the styles
// might be found by the SkinEngine's automatic Style assignment (FrameworkElement.CopyDefaultStyle)
//if (ItemContainerStyle == null || ItemTemplate == null)
// return;
IEnumerable itemsSource = ItemsSource;
if (itemsSource == null)
{ // In this case, we must set up the items control using the Items property
ItemCollection items = _items;
ItemCollection preparedChildren = new ItemCollection();
bool setItems = false;
if (items == null)
{
// Restore items from "ItemsSource mode" where they have been set to null
items = new ItemCollection();
setItems = true;
}
foreach (object item in items)
{
object itemCopy = MpfCopyManager.DeepCopyWithFixedObject(item, this); // Keep this object as LogicalParent
FrameworkElement element = itemCopy as FrameworkElement ?? PrepareItemContainer(itemCopy);
if (element.Style == null && element is ContentControl)
{
element.Style = ItemContainerStyle;
}
element.LogicalParent = this;
preparedChildren.Add(element);
}
presenter.SetDataStrings(BuildDataStrings(items));
SetPreparedItems(setItems, setItems ? items : null, true, preparedChildren);
}
else
{
IList <object> l = new List <object>();
ISynchronizable sync = itemsSource as ISynchronizable;
if (sync != null)
{
lock (sync.SyncRoot)
CollectionUtils.AddAll(l, itemsSource);
}
else
{
CollectionUtils.AddAll(l, itemsSource);
}
presenter.SetDataStrings(BuildDataStrings(l));
var vsp = _itemsHostPanel as IVirtualizingPanel;
if (vsp != null)
{
// In this case, the VSP will generate its items by itself
ListViewItemGenerator lvig = new ListViewItemGenerator();
lvig.Initialize(this, l, ItemContainerStyle, ItemTemplate);
SimplePropertyDataDescriptor dd;
if (SimplePropertyDataDescriptor.CreateSimplePropertyDataDescriptor(this, "IsEmpty", out dd))
{
SetValueInRenderThread(dd, l.Count == 0);
}
vsp.SetItemProvider(lvig);
SetPreparedItems(true, null, false, null);
}
else
{
ItemCollection preparedItems = new ItemCollection();
preparedItems.AddAll(l.Select(PrepareItemContainer));
SetPreparedItems(true, null, true, preparedItems);
}
}
}
/// <summary>
/// Called after the collection of items to be displayed has been set up.
/// </summary>
/// <param name="setItems">If set to <c>true</c>, the <see cref="Items"/> will be set to the given <paramref name="preparedItems"/>,
/// else, the <see cref="Items"/> will be left unchanged.</param>
/// <param name="preparedItems">Elements to be put into the <see cref="Items"/> collection.</param>
/// <param name="setChildren">If set to <c>true</c>, the children of our host panel will be set to the given
/// <paramref name="preparedChildren"/>, else, they will be left unchanged.</param>
/// <param name="preparedChildren">Elements to be put into the <see cref="Panel.Children"/> of our host panel.</param>
protected void SetPreparedItems(bool setItems, ItemCollection preparedItems, bool setChildren, ItemCollection preparedChildren)
{
ItemCollection oldPreparedItems;
ItemCollection oldPreparedChildren;
lock (_renderLock)
{
oldPreparedItems = _preparedItems;
oldPreparedChildren = _preparedChildren;
_preparedItems = preparedItems;
_preparedChildren = preparedChildren;
_setItems = setItems;
_setChildren = setChildren;
}
// If one of those oldXXX properties is set, this method was called multiple times before _preparedItems could be
// used by UpdatePreparedItems, so dispose old items
if (oldPreparedItems != null)
{
oldPreparedItems.Dispose();
}
if (oldPreparedChildren != null)
{
oldPreparedChildren.Dispose();
}
if (_elementState == ElementState.Preparing)
{
// Shortcut in state Preparing - no render thread necessary here to do the UpdatePreparedItems work
UpdatePreparedItems();
}
InvalidateLayout(true, true);
}
/// <summary>
/// Called when the <see cref="Items"/> collection changed.
/// </summary>
/// <param name="collection">The <see cref="Items"/> collection.</param>
void OnItemsCollectionChanged(ItemCollection collection)
{
OnItemsChanged();
}