Select-to-speak event handler

chrome/browser/chromeos/accessibility/select_to_speak_event_handler.h

+// Copyright 2016 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_CHROMEOS_ACCESSIBILITY_SELECT_TO_SPEAK_EVENT_HANDLER_H_
+#define CHROME_BROWSER_CHROMEOS_ACCESSIBILITY_SELECT_TO_SPEAK_EVENT_HANDLER_H_
+
+#include "base/macros.h"
+#include "ui/events/event_handler.h"
+
+namespace chromeos {
+
+// Intercepts mouse events while the Search key is held down, and sends
+// accessibility events to the Select-to-speak extension instead.
+class SelectToSpeakEventHandler : public ui::EventHandler {
+ public:
+  SelectToSpeakEventHandler();
+  ~SelectToSpeakEventHandler() override;
+
+ private:
+  // EventHandler:
+  void OnKeyEvent(ui::KeyEvent* event) override;
+  void OnMouseEvent(ui::MouseEvent* event) override;
+
+  void CancelEvent(ui::Event* event);
+  void SendCancelAXEvent();
+
+  enum State {
+    // Neither the Search key nor the mouse button are down.
+    INACTIVE,
+
+    // The Search key is down but the mouse button is not.
+    SEARCH_DOWN,
+
+    // The user held down Search and clicked the mouse button. We're capturing
+    // all events from now on until either Search or the mouse button is
+    // released.
+    CAPTURING,
+
+    // The mouse was released, but Search is still held down. If the user
+    // clicks again, we'll go back to the state CAPTURING. This is different
+    // than the state SEARCH_DOWN because we know the user clicked at least
+    // once, so when Search is released we'll handle that event too, so as
+    // to not trigger opening the Search UI.
+    MOUSE_RELEASED,
+
+    // The Search key was released while the mouse was still down, cancelling
+    // the Select-to-Speak event. Stay in this mode until the mouse button
+    // is released, too.
+    WAIT_FOR_MOUSE_RELEASE
+  };
+
+  State state_ = INACTIVE;
+
+  int last_view_storage_id_ = 0;
+
+  DISALLOW_COPY_AND_ASSIGN(SelectToSpeakEventHandler);
+};
+
+}  // namespace chromeos
+
+#endif  // CHROME_BROWSER_CHROMEOS_ACCESSIBILITY_SELECT_TO_SPEAK_EVENT_HANDLER_H_