public/fidl/fuchsia.ui.gfx/tokens.fidl

// Copyright 2019 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.gfx;

/// Token that uniquely identifies an attachment point for a subgraph in the
/// global scene graph.  Each |ImportToken| has exactly one corresponding
/// |ExportToken|.
///
/// A Scenic client can reference contents from another client by creating a
/// typed resource using this token.  The other client must also create a
/// correspondingly typed resource using the corresponding |ExportToken|.
///
/// The exact nature of the inter-client reference depends on the specific
/// resources created from the tokens.  For example, creating a |ViewHolder|
/// resource from this token allows a client to embed another client's |View|.
struct ImportToken {
    handle<eventpair> value;
};

/// Token that uniquely identifies a root point for a subgraph in the global
/// scene graph. Each |ExportToken| has exactly one corresponding |ImportToken|.
///
/// A Scenic client can have its contents referenced from another client by
/// creating a typed resource using this token.  The other client must also
/// create a correspondingly typed resource using the corresponding
/// |ImportToken|.
///
/// The exact nature of the inter-client reference depends on the specific
/// resources created from the tokens.  For example, creating a |View|
/// resource from this token allows everything attached to the |View| to be
/// embedded in another clients |ViewHolder|.
struct ExportToken {
    handle<eventpair> value;
};