blob: f848984b28f5292e5bd7fdfe3dcaef4b67282652 [file] [log] [blame]
// 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.views;
/// Problematic situations that occur on Focuser.RequestFocus.
type Error = strict enum {
/// Value returned when RequestFocus is denied.
/// A method of programmatically transferring view focus.
/// The protocol client has implicit access to a requestor ViewRef, which is
/// used as the basis for request authority.
protocol Focuser {
/// Asks the server to transfer focus to the view specified by `view_ref`,
/// with the authority of the requestor ViewRef. Such a request may be
/// honored or denied.
/// If the request was honored, and it triggers a focus change, a FocusEvent
/// (with focused=true) is issued to the newly-focused view, and a
/// FocusEvent (with focused=false) is issued to the previous view.
/// The result callback indicates that the request was received and honored.
/// It does not guarantee that the requested view actually received a
/// FocusEvent in time.
/// The request may be denied for many reasons, for example:
/// - if `view_ref` is invalid
/// - if there is no view backed by `view_ref`
/// - if there is no requestor ViewRef accessible to Focuser
/// - if the requestor ViewRef lacks authority over `view_ref`'s view
/// - if `view_ref`'s view is not hittable or may not receive focus
/// etc. A denied request is indicated with a Error.
RequestFocus(resource struct {
view_ref ViewRef;
}) -> (struct {}) error Error;