blob: ebd40dac7ff4004a7e0e6e183be39274dc619274 [file] [log] [blame]
// Copyright 2017 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
import 'dart:async';
import 'dart:ui' show TextDirection;
import 'package:flutter/services.dart' show SystemChannels;
import 'semantics_event.dart' show AnnounceSemanticsEvent, TooltipSemanticsEvent;
/// Allows access to the platform's accessibility services.
/// Events sent by this service are handled by the platform-specific
/// accessibility bridge in Flutter's engine.
/// When possible, prefer using mechanisms like [Semantics] to implicitly
/// trigger announcements over using this event.
class SemanticsService {
/// Sends a semantic announcement.
/// This should be used for announcement that are not seamlessly announced by
/// the system as a result of a UI state change.
/// For example a camera application can use this method to make accessibility
/// announcements regarding objects in the viewfinder.
static Future<Null> announce(String message, TextDirection textDirection) async {
final AnnounceSemanticsEvent event = new AnnounceSemanticsEvent(message, textDirection);
await SystemChannels.accessibility.send(event.toMap());
/// Sends a semantic announcement of a tooltip.
/// This is only used by Android.
static Future<Null> tooltip(String message) async {
final TooltipSemanticsEvent event = new TooltipSemanticsEvent(message);
await SystemChannels.accessibility.send(event.toMap());