// Copyright 2021 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.observation.test;

using fuchsia.ui.observation.geometry;

/// *** ONLY FOR USE IN TESTS ***
/// This is a sensitive protocol. It provides unlimited access to the global
/// view tree. Hand it out ONLY to test components.
///
/// Production uses should obtain observation protocols through a graphics
/// factory function (see |fuchsia.ui.composition.ViewBoundProtocols|), which
/// securely ties observation protocols to a specific view client.
@discoverable
protocol Registry {
    /// Sets up a channel for receiving global view geometry.
    ///
    /// This method may be called multiple times to obtain multiple geometry
    /// `ViewTreeWatcher`s, if necesary. However, typical test usage is to
    /// obtain just one geometry `ViewTreeWatcher` in the test component.
    ///
    /// Flow control. The caller is allowed at most one in-flight call at a
    /// time. Subsequent calls must wait until the acknowledgment returns.
    /// Non-compliance results in channel closure.
    ///
    /// Client can freely disconnect this `Registry` endpoint after this method
    /// returns.
    RegisterGlobalViewTreeWatcher(resource struct {
        watcher server_end:fuchsia.ui.observation.geometry.ViewTreeWatcher;
    }) -> ();
};