Add an accessibility API for events raised outside of the web content.

chrome/browser/gtk/accessibility_event_router_gtk.h

+// 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_GTK_ACCESSIBILITY_EVENT_ROUTER_GTK_H_
+#define CHROME_BROWSER_GTK_ACCESSIBILITY_EVENT_ROUTER_GTK_H_
+
+#include <gtk/gtk.h>
+
+#include <string>
+#include <vector>
+
+#include "base/basictypes.h"
+#include "base/hash_tables.h"
+#include "base/singleton.h"
+#include "chrome/common/accessibility_events.h"
+
+class Profile;
+
+// Allows us to use (GtkWidget*) in a hash_map with gcc.
+namespace __gnu_cxx {
+template<>
+struct hash<GtkWidget*> {
+  size_t operator()(GtkWidget* widget) const {
+    return reinterpret_cast<size_t>(widget);
+  }
+};
+}  // namespace __gnu_cxx
+
+// Singleton class that adds a signal emission hook to many gtk events, and
+// then sends an accessibility notification whenever a relevant event is
+// sent to an accessible control.
+//
+// Gtk widgets are not accessible by default. When you register a root widget,
+// that widget and all of its descendants will start sending accessibility
+// event notifications. You can then override the default behavior for
+// specific descendants using other methods.
+//
+// You can use Profile::PauseAccessibilityEvents to prevent a flurry
+// of accessibility events when a window is being created or initialized.
+class AccessibilityEventRouter {
+ public:
+  // Internal information about a particular widget to override the
+  // information we get directly from gtk.
+  struct WidgetInfo {
+    // If nonempty, will use this name instead of the widget's label.
+    std::string name;
+
+    // If true, will ignore this widget and not send accessibility events.
+    bool ignore;
+  };
+
+  // Get the single instance of this class.
+  static AccessibilityEventRouter* GetInstance();
+
+  // Start sending accessibility events for this widget and all of its
+  // descendants.  Notifications will go to the specified profile.
+  void AddRootWidget(GtkWidget* root_widget, Profile* profile);
+
+  // Stop sending accessibility events for this widget and all of its
+  // descendants.
+  void RemoveRootWidget(GtkWidget* root_widget);
+
+  // Don't send any events for this widget.
+  void IgnoreWidget(GtkWidget* widget);
+
+  // Use the following string as the name of this widget, instead of the
+  // gtk label associated with the widget.
+  void SetWidgetName(GtkWidget* widget, std::string name);
+
+  // Forget all information about this widget.
+  void RemoveWidget(GtkWidget* widget);
+
+  //
+  // The following methods are only for use by gtk signal handlers.
+  //
+
+  // Returns true if this widget is a descendant of one of our registered
+  // root widgets and not in the set of ignored widgets.  If |profile| is
+  // not null, return the profile where notifications associated with this
+  // widget should be sent.
+  bool IsWidgetAccessible(GtkWidget* widget, Profile** profile);
+
+  // Return the name of a widget.
+  std::string GetWidgetName(GtkWidget* widget);
+
+  // Called by the signal handler.  Checks the type of the widget and
+  // calls one of the more specific Send*Notification methods, below.
+  void DispatchAccessibilityNotification(
+      GtkWidget* widget, NotificationType type);
+
+  // Each of these methods constructs an AccessibilityControlInfo object
+  // and sends a notification of a specific accessibility event.
+  void SendRadioButtonNotification(
+      GtkWidget* widget, NotificationType type, Profile* profile);
+  void SendCheckboxNotification(
+      GtkWidget* widget, NotificationType type, Profile* profile);
+  void SendButtonNotification(
+      GtkWidget* widget, NotificationType type, Profile* profile);
+  void SendTextBoxNotification(
+      GtkWidget* widget, NotificationType type, Profile* profile);
+  void SendTabNotification(
+      GtkWidget* widget, NotificationType type, Profile* profile);
+
+  void InstallEventListeners();
+  void RemoveEventListeners();
+
+ private:
+  AccessibilityEventRouter();
+  virtual ~AccessibilityEventRouter() {}
+
+  friend struct DefaultSingletonTraits<AccessibilityEventRouter>;
+
+  // The set of all root widgets; only descendants of these will generate
+  // accessibility notifications.
+  base::hash_map<GtkWidget*, Profile*> root_widget_profile_map_;
+
+  // Extra information about specific widgets.
+  base::hash_map<GtkWidget*, WidgetInfo> widget_info_map_;
+
+  // Installed event listener hook ids so we can remove them later.
+  gulong focus_hook_;
+  gulong click_hook_;
+  gulong toggle_hook_;
+  gulong switch_page_hook_;
+
+  std::vector<gulong> event_listener_hook_ids_;
+};
+
+#endif  // CHROME_BROWSER_GTK_ACCESSIBILITY_EVENT_ROUTER_GTK_H_