// Copyright 2018 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

library fuchsia.ui.views;

union Event {
    ChildViewAttachedEvent child_view_attached;
    ChildViewUnavailableEvent child_view_unavailable;
};

/// Called when a child view is attached.
struct ChildViewAttachedEvent {
    uint32 view_holder_id;
};

/// Called when a child view has become unavailable.
///
/// A child may become unavailable for many reasons such being unregistered
/// by its application, abnormal termination of its application, or
/// cycles being introduced in the view tree.
///
/// To complete removal of an unavailable child, this view component must
/// call RemoveChild() on its view with |child_key|.
///
/// The implementation should invoke the callback once the event has
/// been handled.
struct ChildViewUnavailableEvent {
    uint32 view_holder_id;
};