/// <summary>
/// Disconnects a child.
/// </summary>
private void DisconnectChild(int index)
{
Debug.Assert(_items[index] != null);
Visual child = _items[index];
//
// -- Approved By The Core Team --
//
// Do not allow foreign threads to change the tree.
// (This is a noop if this object is not assigned to a Dispatcher.)
//
child.VerifyAccess();
Visual oldParent = VisualTreeHelper.GetContainingVisual2D(child._parent);
int oldParentIndex = child._parentIndex;
// It is invalid to modify the children collection that we
// might be iterating during a property invalidation tree walk.
if (oldParent.IsVisualChildrenIterationInProgress)
{
throw new InvalidOperationException(SR.Get(SRID.CannotModifyVisualChildrenDuringTreeWalk));
}
_items[index] = null;
#if DEBUG
child._parentIndex = -1;
#endif
IncrementVersion();
_owner.InternalRemoveVisualChild(child);
}
/// <summary>
/// Sets the specified visual at the specified index into the child
/// collection. It also corrects the parent.
/// Note that the function requires that _item[index] == null and it
/// also requires that the passed in child is not connected to another Visual.
/// </summary>
/// <exception cref="ArgumentException">If the new child has already a parent or if the slot a the specified index is not null.</exception>
private void ConnectChild(int index, Visual value)
{
//
// -- Approved By The Core Team --
//
// Do not allow foreign threads to change the tree.
// (This is a noop if this object is not assigned to a Dispatcher.)
//
// We also need to ensure that the tree is homogenous with respect
// to the dispatchers that the elements belong to.
//
_owner.VerifyAccess();
value.VerifyAccess();
// It is invalid to modify the children collection that we
// might be iterating during a property invalidation tree walk.
if (_owner.IsVisualChildrenIterationInProgress)
{
throw new InvalidOperationException(SR.Get(SRID.CannotModifyVisualChildrenDuringTreeWalk));
}
Debug.Assert(value != null);
Debug.Assert(_items[index] == null);
Debug.Assert(value._parent == null);
Debug.Assert(!value.IsRootElement);
value._parentIndex = index;
_items[index] = value;
IncrementVersion();
// Notify the Visual tree about the children changes.
_owner.InternalAddVisualChild(value);
}
/// <summary>
/// Sets the specified visual at the specified index into the child
/// collection. It also corrects the parent.
/// Note that the function requires that _item[index] == null and it
/// also requires that the passed in child is not connected to another Visual.
/// </summary>
/// <exception cref="ArgumentException">If the new child has already a parent or if the slot a the specified index is not null.</exception>
private void ConnectChild(int index, Visual value)
{
//
// -- Approved By The Core Team --
//
// Do not allow foreign threads to change the tree.
// (This is a noop if this object is not assigned to a Dispatcher.)
//
// We also need to ensure that the tree is homogenous with respect
// to the dispatchers that the elements belong to.
//
_owner.VerifyAccess();
value.VerifyAccess();
// It is invalid to modify the children collection that we
// might be iterating during a property invalidation tree walk.
if (_owner.IsVisualChildrenIterationInProgress)
{
throw new InvalidOperationException(SR.Get(SRID.CannotModifyVisualChildrenDuringTreeWalk));
}
Debug.Assert(value != null);
Debug.Assert(_items[index] == null);
Debug.Assert(value._parent == null);
Debug.Assert(!value.IsRootElement);
value._parentIndex = index;
_items[index] = value;
IncrementVersion();
// Notify the Visual tree about the children changes.
_owner.InternalAddVisualChild(value);
}