chrome/browser/accessibility/accessibility_extension_api.h

   1 // Copyright (c) 2012 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_ACCESSIBILITY_ACCESSIBILITY_EXTENSION_API_H_
   6 #define CHROME_BROWSER_ACCESSIBILITY_ACCESSIBILITY_EXTENSION_API_H_
   7
   8 #include <string>
   9
  10 #include "base/compiler_specific.h"
  11 #include "base/memory/singleton.h"
  12 #include "base/values.h"
  13 #include "chrome/browser/accessibility/accessibility_events.h"
  14 #include "chrome/browser/extensions/chrome_extension_function.h"
  15 #include "ui/base/accessibility/accessibility_types.h"
  16
  17 namespace extensions {
  18 class ExtensionHost;
  19 } // namespace extensions
  20
  21 // Observes the profile and routes accessibility notifications as events
  22 // to the extension system.
  23 class ExtensionAccessibilityEventRouter {
  24  public:
  25   typedef base::Callback<void(ui::AccessibilityTypes::Event,
  26                               const AccessibilityControlInfo*)>
  27       ControlEventCallback;
  28   // Single instance of the event router.
  29   static ExtensionAccessibilityEventRouter* GetInstance();
  30
  31   // Get the dict representing the last control that received an
  32   // OnControlFocus event.
  33   base::DictionaryValue* last_focused_control_dict() {
  34     return &last_focused_control_dict_;
  35   }
  36
  37   // Accessibility support is disabled until an extension expicitly enables
  38   // it, so that this extension api has no impact on Chrome's performance
  39   // otherwise.  These methods handle enabling, disabling, and querying the
  40   // status.
  41   void SetAccessibilityEnabled(bool enabled);
  42   bool IsAccessibilityEnabled() const;
  43
  44   // Set and remove callbacks (used for testing, to confirm that events are
  45   // getting through).
  46   void SetControlEventCallbackForTesting(ControlEventCallback callback);
  47   void ClearControlEventCallback();
  48
  49   // Route a window-related accessibility event.
  50   void HandleWindowEvent(ui::AccessibilityTypes::Event event,
  51                          const AccessibilityWindowInfo* info);
  52
  53   // Route a menu-related accessibility event.
  54   void HandleMenuEvent(ui::AccessibilityTypes::Event event,
  55                        const AccessibilityMenuInfo* info);
  56
  57   // Route a control-related accessibility event.
  58   void HandleControlEvent(ui::AccessibilityTypes::Event event,
  59                           const AccessibilityControlInfo* info);
  60
  61   void OnChromeVoxLoadStateChanged(
  62       Profile* profile,
  63       bool loading,
  64       bool make_announcements);
  65
  66   static void DispatchEventToChromeVox(
  67       Profile* profile,
  68       const char* event_name,
  69       scoped_ptr<base::ListValue> event_args);
  70
  71  private:
  72   friend struct DefaultSingletonTraits<ExtensionAccessibilityEventRouter>;
  73
  74   ExtensionAccessibilityEventRouter();
  75   virtual ~ExtensionAccessibilityEventRouter();
  76
  77   void OnWindowOpened(const AccessibilityWindowInfo* details);
  78   void OnControlFocused(const AccessibilityControlInfo* details);
  79   void OnControlAction(const AccessibilityControlInfo* details);
  80   void OnTextChanged(const AccessibilityControlInfo* details);
  81   void OnMenuOpened(const AccessibilityMenuInfo* details);
  82   void OnMenuClosed(const AccessibilityMenuInfo* details);
  83
  84   void DispatchEvent(Profile* profile,
  85                      const char* event_name,
  86                      scoped_ptr<base::ListValue> event_args);
  87
  88   base::DictionaryValue last_focused_control_dict_;
  89
  90   bool enabled_;
  91
  92   // For testing.
  93   ControlEventCallback control_event_callback_;
  94
  95   DISALLOW_COPY_AND_ASSIGN(ExtensionAccessibilityEventRouter);
  96 };
  97
  98 // API function that enables or disables accessibility support.  Event
  99 // listeners are only installed when accessibility support is enabled, to
 100 // minimize the impact.
 101 class AccessibilitySetAccessibilityEnabledFunction
 102     : public ChromeSyncExtensionFunction {
 103   virtual ~AccessibilitySetAccessibilityEnabledFunction() {}
 104   virtual bool RunImpl() OVERRIDE;
 105   DECLARE_EXTENSION_FUNCTION(
 106       "experimental.accessibility.setAccessibilityEnabled",
 107       EXPERIMENTAL_ACCESSIBILITY_SETACCESSIBILITYENABLED)
 108 };
 109
 110 // API function that enables or disables web content accessibility support.
 111 class AccessibilitySetNativeAccessibilityEnabledFunction
 112     : public ChromeSyncExtensionFunction {
 113   virtual ~AccessibilitySetNativeAccessibilityEnabledFunction() {}
 114   virtual bool RunImpl() OVERRIDE;
 115   DECLARE_EXTENSION_FUNCTION(
 116       "experimental.accessibility.setNativeAccessibilityEnabled",
 117       EXPERIMENTAL_ACCESSIBILITY_SETNATIVEACCESSIBILITYENABLED)
 118 };
 119
 120 // API function that returns the most recent focused control.
 121 class AccessibilityGetFocusedControlFunction
 122     : public ChromeSyncExtensionFunction {
 123   virtual ~AccessibilityGetFocusedControlFunction() {}
 124   virtual bool RunImpl() OVERRIDE;
 125   DECLARE_EXTENSION_FUNCTION(
 126       "experimental.accessibility.getFocusedControl",
 127       EXPERIMENTAL_ACCESSIBILITY_GETFOCUSEDCONTROL)
 128 };
 129
 130 // API function that returns alerts being shown on the give tab.
 131 class AccessibilityGetAlertsForTabFunction
 132     : public ChromeSyncExtensionFunction {
 133   virtual ~AccessibilityGetAlertsForTabFunction() {}
 134   virtual bool RunImpl() OVERRIDE;
 135   DECLARE_EXTENSION_FUNCTION(
 136       "experimental.accessibility.getAlertsForTab",
 137       EXPERIMENTAL_ACCESSIBILITY_GETALERTSFORTAB)
 138 };
 139
 140 #endif  // CHROME_BROWSER_ACCESSIBILITY_ACCESSIBILITY_EXTENSION_API_H_