extension_accessibility_api.h revision 731df977c0511bca2206b5f333555b1205ff1f43 
1// Copyright (c) 2010 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#ifndef CHROME_BROWSER_EXTENSIONS_EXTENSION_ACCESSIBILITY_API_H_
6#define CHROME_BROWSER_EXTENSIONS_EXTENSION_ACCESSIBILITY_API_H_
7#pragma once
8
9#include <string>
10#include <vector>
11
12#include "base/callback.h"
13#include "base/singleton.h"
14#include "base/values.h"
15#include "chrome/browser/accessibility_events.h"
16#include "chrome/browser/extensions/extension_function.h"
17#include "chrome/common/notification_observer.h"
18#include "chrome/common/notification_registrar.h"
19
20// Observes the profile and routes accessibility notifications as events
21// to the extension system.
22class ExtensionAccessibilityEventRouter : public NotificationObserver {
23 public:
24  // Single instance of the event router.
25  static ExtensionAccessibilityEventRouter* GetInstance();
26
27  // Safe to call multiple times.
28  void ObserveProfile(Profile* profile);
29
30  // Get the dict representing the last control that received an
31  // OnControlFocus event.
32  DictionaryValue* last_focused_control_dict() {
33    return &last_focused_control_dict_;
34  }
35
36  // Accessibility support is disabled until an extension expicitly enables
37  // it, so that this extension api has no impact on Chrome's performance
38  // otherwise.  These methods handle enabling, disabling, querying the
39  // status, and installing callbacks to execute when accessibility support
40  // is enabled or disabled.
41  void SetAccessibilityEnabled(bool enabled);
42  bool IsAccessibilityEnabled() const;
43  typedef Callback0::Type Callback;
44  void AddOnEnabledListener(Callback* callback);
45  void AddOnDisabledListener(Callback* callback);
46
47 private:
48  friend struct DefaultSingletonTraits<ExtensionAccessibilityEventRouter>;
49
50  ExtensionAccessibilityEventRouter();
51  virtual ~ExtensionAccessibilityEventRouter();
52
53  // NotificationObserver::Observe.
54  virtual void Observe(NotificationType type,
55                       const NotificationSource& source,
56                       const NotificationDetails& details);
57
58  void OnWindowOpened(const AccessibilityWindowInfo* details);
59  void OnWindowClosed(const AccessibilityWindowInfo* details);
60  void OnControlFocused(const AccessibilityControlInfo* details);
61  void OnControlAction(const AccessibilityControlInfo* details);
62  void OnTextChanged(const AccessibilityControlInfo* details);
63  void OnMenuOpened(const AccessibilityMenuInfo* details);
64  void OnMenuClosed(const AccessibilityMenuInfo* details);
65
66  void DispatchEvent(Profile* profile,
67                     const char* event_name,
68                     const std::string& json_args);
69
70  // Used for tracking registrations to history service notifications.
71  NotificationRegistrar registrar_;
72
73  DictionaryValue last_focused_control_dict_;
74
75  bool enabled_;
76  std::vector<Callback*> on_enabled_listeners_;
77  std::vector<Callback*> on_disabled_listeners_;
78
79  DISALLOW_COPY_AND_ASSIGN(ExtensionAccessibilityEventRouter);
80};
81
82// API function that enables or disables accessibility support.  Event
83// listeners are only installed when accessibility support is enabled, to
84// minimize the impact.
85class SetAccessibilityEnabledFunction : public SyncExtensionFunction {
86  virtual ~SetAccessibilityEnabledFunction() {}
87  virtual bool RunImpl();
88  DECLARE_EXTENSION_FUNCTION_NAME(
89      "experimental.accessibility.setAccessibilityEnabled")
90};
91
92// API function that returns the most recent focused control.
93class GetFocusedControlFunction : public SyncExtensionFunction {
94  virtual ~GetFocusedControlFunction() {}
95  virtual bool RunImpl();
96  DECLARE_EXTENSION_FUNCTION_NAME(
97      "experimental.accessibility.getFocusedControl")
98};
99
100#endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_ACCESSIBILITY_API_H_
101