private void OnItemContainerGeneratorChanged(object sender, ItemsChangedEventArgs e)
{
if (this.itemsPresenter == null || this.itemsPresenter.Child is VirtualizingPanel)
{
return;
}
Panel panel = this.itemsPresenter.Child;
switch (e.Action)
{
case NotifyCollectionChangedAction.Reset:
// the list has gone away, so clear the children of the panel
if (panel.InternalChildren.Count > 0)
{
this.RemoveItemsFromPresenter(new GeneratorPosition(0, 0), panel.InternalChildren.Count);
}
break;
case NotifyCollectionChangedAction.Add:
this.AddItemsToPresenter(e.Position, e.ItemCount);
break;
case NotifyCollectionChangedAction.Remove:
this.RemoveItemsFromPresenter(e.Position, e.ItemCount);
break;
case NotifyCollectionChangedAction.Replace:
this.RemoveItemsFromPresenter(e.Position, e.ItemCount);
this.AddItemsToPresenter(e.Position, e.ItemCount);
break;
}
}
internal void OnOwnerItemsItemsChanged(object sender, NotifyCollectionChangedEventArgs e)
{
int itemCount;
int itemUICount;
GeneratorPosition oldPosition = new GeneratorPosition(-1, 0);
GeneratorPosition position;
switch (e.Action)
{
case NotifyCollectionChangedAction.Add:
if ((e.NewStartingIndex + 1) != this.Owner.Items.Count)
{
this.MoveExistingItems(e.NewStartingIndex, 1);
}
itemCount = 1;
itemUICount = 0;
position = this.GeneratorPositionFromIndex(e.NewStartingIndex);
break;
case NotifyCollectionChangedAction.Remove:
itemCount = 1;
itemUICount = this.RealizedElements.Contains(e.OldStartingIndex) ? 1 : 0;
position = this.GeneratorPositionFromIndex(e.OldStartingIndex);
if (itemUICount == 1)
{
this.Remove(position, 1);
}
this.MoveExistingItems(e.OldStartingIndex, -1);
break;
case NotifyCollectionChangedAction.Replace:
if (!this.RealizedElements.Contains(e.NewStartingIndex))
{
return;
}
itemCount = 1;
itemUICount = 1;
position = this.GeneratorPositionFromIndex(e.NewStartingIndex);
this.Remove(position, 1);
bool fresh;
var newPos = this.GeneratorPositionFromIndex(e.NewStartingIndex);
using (this.StartAt(newPos, GeneratorDirection.Forward, true))
{
this.PrepareItemContainer(this.GenerateNext(out fresh));
}
break;
case NotifyCollectionChangedAction.Reset:
itemCount = e.OldItems == null ? 0 : e.OldItems.Count;
itemUICount = this.RealizedElements.Count;
position = new GeneratorPosition(-1, 0);
this.RemoveAll();
break;
default:
Console.WriteLine("*** Critical error in ItemContainerGenerator.OnOwnerItemsItemsChanged. NotifyCollectionChangedAction.{0} is not supported", e.Action);
return;
}
ItemsChangedEventArgs args = new ItemsChangedEventArgs
{
Action = e.Action,
ItemCount = itemCount,
ItemUICount = itemUICount,
OldPosition = oldPosition,
Position = position
};
var h = this.ItemsChanged;
if (h != null)
{
h(this, args);
}
}
