Home | History | Annotate | Download | only in extensions 
      1 // Copyright (c) 2011 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/memory/singleton.h"
     14 #include "base/values.h"
     15 #include "chrome/browser/accessibility_events.h"
     16 #include "chrome/browser/extensions/extension_function.h"
     17 #include "content/common/notification_observer.h"
     18 #include "content/common/notification_registrar.h"
     19 
     20 // Observes the profile and routes accessibility notifications as events
     21 // to the extension system.
     22 class 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.
     85 class 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.
     93 class 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