// Copyright 2016 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.policy;

using fuchsia.ui.views;

/// The Presenter service provides a way for applications to ask that a view be
/// added to a view tree, leaving any window management concerns up to the
/// discretion of the presenter implementation.
[Discoverable]
protocol Presenter {
    /// Request that the View's contents be displayed on the screen as a `Presentation`.
    /// Each call to `PresentView` creates a new `Presentation`. Having more than one simultaneous
    /// `Presentation` (i.e. calling `PresentView` more than once) is not allowed and will result
    // in an error and channel closure.
    PresentView(fuchsia.ui.views.ViewHolderToken view_holder_token, request<Presentation>? presentation_request);

    /// Request that the View's contents be displayed on the screen as a `Presentation`.
    /// Destroys any existing presentations and replaces them with the new one.
    /// This is true whether the existing view was created by a call to
    /// PresentView, PresentOrReplaceView or PresentOrReplaceView2.
    PresentOrReplaceView(fuchsia.ui.views.ViewHolderToken view_holder_token, request<Presentation>? presentation_request);

    // Same as PresentOrReplaceView, except it also takes a ViewRef.
    // The ViewRef should be referring to the same View as the ViewHolderToken.
    // The ViewRef is used for transfering focus the View after initialization.
    PresentOrReplaceView2(fuchsia.ui.views.ViewHolderToken view_holder_token,
                          fuchsia.ui.views.ViewRef view_ref,
                          request<Presentation>? presentation_request);
};