private static IList<ItemContainerInfo> AddContainers(
ItemsPresenterBase owner,
int index,
IEnumerable items)
{
var generator = owner.ItemContainerGenerator;
var result = new List<ItemContainerInfo>();
var panel = owner.Panel;
foreach (var item in items)
{
var i = generator.Materialize(index++, item, owner.MemberSelector);
if (i.ContainerControl != null)
{
if (i.Index < panel.Children.Count)
{
// TODO: This will insert at the wrong place when there are null items.
panel.Children.Insert(i.Index, i.ContainerControl);
}
else
{
panel.Children.Add(i.ContainerControl);
}
}
result.Add(i);
}
return result;
}
public static void ItemsChanged(
ItemsPresenterBase owner,
IEnumerable items,
NotifyCollectionChangedEventArgs e)
{
var generator = owner.ItemContainerGenerator;
var panel = owner.Panel;
if (panel == null)
{
return;
}
void Add()
{
if (e.NewStartingIndex + e.NewItems.Count < items.Count())
{
generator.InsertSpace(e.NewStartingIndex, e.NewItems.Count);
}
AddContainers(owner, e.NewStartingIndex, e.NewItems);
}
void Remove()
{
RemoveContainers(panel, generator.RemoveRange(e.OldStartingIndex, e.OldItems.Count));
}
switch (e.Action)
{
case NotifyCollectionChangedAction.Add:
Add();
break;
case NotifyCollectionChangedAction.Remove:
Remove();
break;
case NotifyCollectionChangedAction.Replace:
RemoveContainers(panel, generator.Dematerialize(e.OldStartingIndex, e.OldItems.Count));
var containers = AddContainers(owner, e.NewStartingIndex, e.NewItems);
var i = e.NewStartingIndex;
foreach (var container in containers)
{
panel.Children[i++] = container.ContainerControl;
}
break;
case NotifyCollectionChangedAction.Move:
Remove();
Add();
break;
case NotifyCollectionChangedAction.Reset:
RemoveContainers(panel, generator.Clear());
if (items != null)
{
AddContainers(owner, 0, items);
}
break;
}
}
