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// 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.
using fuchsia.sys;
/// ViewProvider is the standard mechanism for two modules to each obtain half
/// of a shared eventpair token. The shared token is a capability allowing the
/// modules to ask Scenic to create a ViewHolder/View pair. The resulting
/// View and ViewHolder are linked together until either one is destroyed.
/// Modules are free to use any other mechanism to agree upon the shared
/// eventpair token, and use this to create the linked ViewHolder/View.
/// ViewProvider is given for the convenience of clients that don't require
/// a more complex implementation.
protocol ViewProvider {
/// Creates a new View under the control of the ViewProvider.
/// `token` is one half of the shared eventpair which will bind the new View
/// to its associated ViewHolder. The ViewProvider will use `token` to
/// create its internal View representation. The caller is expected to use
/// its half to create corresponding ViewHolder object.
/// `incoming_services` allows clients to request services from the
/// ViewProvider implementation. `outgoing_services` allows clients to
/// provide services of their own to the ViewProvider implementation.
/// Clients can embed a ViewHolder (and by proxy the paired View) into their
/// scene graph by using `Node.AddChild()`. The ViewHolder cannot itself
/// have any children. A ViewProvider implementation can nest scene objects
/// within its View by using `View.AddChild()`. The View itself
/// cannot be a child of anything.
/// Modules can use these mechanisms to establish a distributed,
/// inter-process scene graph.
CreateView(handle<eventpair> token,
request<fuchsia.sys.ServiceProvider>? incoming_services,
fuchsia.sys.ServiceProvider? outgoing_services);