// Copyright (c) 2010 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. #ifndef CHROME_BROWSER_ACCESSIBILITY_BROWSER_ACCESSIBILITY_STATE_H_ #define CHROME_BROWSER_ACCESSIBILITY_BROWSER_ACCESSIBILITY_STATE_H_ #pragma once #include "base/basictypes.h" template <typename T> struct DefaultSingletonTraits; // The BrowserAccessibilityState class is used to determine if Chrome should be // customized for users with assistive technology, such as screen readers. We // modify the behavior of certain user interfaces to provide a better experience // for screen reader users. The way we detect a screen reader program is // different for each platform. // // Screen Reader Detection // (1) On windows many screen reader detection mechinisms will give false // positives like relying on the SPI_GETSCREENREADER system parameter. In Chrome // we attempt to dynamically detect a MSAA client screen reader by calling // NotifiyWinEvent in WidgetWin with a custom ID and wait to see if the ID // is requested by a subsequent call to WM_GETOBJECT. // (2) On mac we detect if VoiceOver is running. This is stored in a preference // file for Universal Access with the key "voiceOverOnOffKey". class BrowserAccessibilityState { public: // Returns the singleton instance. static BrowserAccessibilityState* GetInstance(); ~BrowserAccessibilityState(); // Called when screen reader client is detected. void OnScreenReaderDetected(); // Returns true if the Chrome browser should be customized for accessibility. bool IsAccessibleBrowser(); private: BrowserAccessibilityState(); friend struct DefaultSingletonTraits<BrowserAccessibilityState>; // Set to true when a screen reader client is detected. bool screen_reader_active_; DISALLOW_COPY_AND_ASSIGN(BrowserAccessibilityState); }; #endif // CHROME_BROWSER_ACCESSIBILITY_BROWSER_ACCESSIBILITY_STATE_H_