Long press menu (shift+f6) to toggle spoken feedback.

ash/magnifier/magnifier_key_scroller.h

-// Copyright 2014 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 ASH_MAGNIFIER_MAGNIFIER_KEY_SCROLLER_H_
-#define ASH_MAGNIFIER_MAGNIFIER_KEY_SCROLLER_H_
-
-#include "ash/ash_export.h"
-#include "ui/events/event_handler.h"
-
-namespace ui {
-class KeyEvent;
-}
-
-namespace ash {
-
-// This class implements the press and hold key-bindings (shift-arrow keys)
-// to control magnified screen.
-class ASH_EXPORT MagnifierKeyScroller : public ui::EventHandler {
- public:
-  static bool IsEnabled();
-  static void SetEnabled(bool enabled);
-
-  MagnifierKeyScroller();
-  virtual ~MagnifierKeyScroller();
-
-  // ui::EventHandler overrides:
-  virtual void OnKeyEvent(ui::KeyEvent* key_event) OVERRIDE;
-
-  // A scoped object to enable and disable the magnifier accelerator for test.
-  class ScopedEnablerForTest {
-   public:
-    ScopedEnablerForTest() {
-      SetEnabled(true);
-    }
-    ~ScopedEnablerForTest() {
-      SetEnabled(false);
-    }
-
-   private:
-    DISALLOW_COPY_AND_ASSIGN(ScopedEnablerForTest);
-  };
-
- private:
-  // A state to keep track of one click and click and hold operation.
-  //
-  // One click:
-  // INITIAL --(first press)--> PRESSED --(release)--> INITIAL[SEND PRESS]
-  //
-  // Click and hold:
-  // INITIAL --(first press)--> PRESSED --(press)-->
-  //   HOLD[scroll] --(press)--> HOLD[scroll] --(release)-->
-  //   INITIAL[stop scroll]
-  enum State {
-    INITIAL,
-    PRESSED,
-    HOLD
-  };
-
-  State state_;
-
-  DISALLOW_COPY_AND_ASSIGN(MagnifierKeyScroller);
-};
-
-}  // namespace ash
-
-#endif  // ASH_MAGNIFIER_MAGNIFIER_KEY_SCROLLER_H_