/// <summary>
/// Called when the <see cref="Children"/> collection changes.
/// </summary>
/// <param name="sender">The event sender.</param>
/// <param name="e">The event args.</param>
private void ChildrenChanged(object sender, NotifyCollectionChangedEventArgs e)
{
List <Control> controls;
// TODO: Handle Replace.
switch (e.Action)
{
case NotifyCollectionChangedAction.Add:
controls = e.NewItems.OfType <Control>().ToList();
SetLogicalParent(controls);
AddVisualChildren(e.NewItems.OfType <Visual>());
LogicalChildren.InsertRange(e.NewStartingIndex, controls);
break;
case NotifyCollectionChangedAction.Remove:
controls = e.OldItems.OfType <Control>().ToList();
ClearLogicalParent(e.OldItems.OfType <Control>());
LogicalChildren.RemoveAll(controls);
RemoveVisualChildren(e.OldItems.OfType <Visual>());
break;
case NotifyCollectionChangedAction.Reset:
controls = e.OldItems.OfType <Control>().ToList();
ClearLogicalParent(controls);
LogicalChildren.Clear();
ClearVisualChildren();
AddVisualChildren(_children);
break;
}
InvalidateMeasure();
}
/// <summary>
/// Called when containers are recycled for the <see cref="ItemsControl"/> by its
/// <see cref="ItemContainerGenerator"/>.
/// </summary>
/// <param name="e">The details of the containers.</param>
protected virtual void OnContainersRecycled(ItemContainerEventArgs e)
{
var toRemove = new List <ILogical>();
foreach (var container in e.Containers)
{
// If the item is its own container, then it will be removed from the logical tree
// when it is removed from the Items collection.
if (container?.ContainerControl != container?.Item)
{
toRemove.Add(container.ContainerControl);
}
}
LogicalChildren.RemoveAll(toRemove);
}
/// <summary>
/// Given a collection of items, removes those that are controls to from logical children.
/// </summary>
/// <param name="items">The items.</param>
private void RemoveControlItemsFromLogicalChildren(IEnumerable items)
{
var toRemove = new List <ILogical>();
if (items != null)
{
foreach (var i in items)
{
var control = i as IControl;
if (control != null)
{
toRemove.Add(control);
}
}
}
LogicalChildren.RemoveAll(toRemove);
}
/// <summary>
/// Called when the <see cref="Children"/> collection changes.
/// </summary>
/// <param name="sender">The event sender.</param>
/// <param name="e">The event args.</param>
protected virtual void ChildrenChanged(object sender, NotifyCollectionChangedEventArgs e)
{
List <Control> controls;
switch (e.Action)
{
case NotifyCollectionChangedAction.Add:
controls = e.NewItems.OfType <Control>().ToList();
LogicalChildren.InsertRange(e.NewStartingIndex, controls);
VisualChildren.InsertRange(e.NewStartingIndex, e.NewItems.OfType <Visual>());
break;
case NotifyCollectionChangedAction.Move:
LogicalChildren.MoveRange(e.OldStartingIndex, e.OldItems.Count, e.NewStartingIndex);
VisualChildren.MoveRange(e.OldStartingIndex, e.OldItems.Count, e.NewStartingIndex);
break;
case NotifyCollectionChangedAction.Remove:
controls = e.OldItems.OfType <Control>().ToList();
LogicalChildren.RemoveAll(controls);
VisualChildren.RemoveAll(e.OldItems.OfType <Visual>());
break;
case NotifyCollectionChangedAction.Replace:
for (var i = 0; i < e.OldItems.Count; ++i)
{
var index = i + e.OldStartingIndex;
var child = (IControl)e.NewItems[i];
LogicalChildren[index] = child;
VisualChildren[index] = child;
}
break;
case NotifyCollectionChangedAction.Reset:
throw new NotSupportedException();
}
InvalidateMeasure();
}