text: // 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.
  
  #include "ash/accelerators/magnifier_key_scroller.h"
  
  #include <utility>
  
  #include "ash/accelerators/key_hold_detector.h"
  #include "ash/accessibility/magnifier/fullscreen_magnifier_controller.h"
  #include "ash/constants/ash_switches.h"
  #include "ash/keyboard/keyboard_util.h"
  #include "ash/shell.h"
  #include "base/command_line.h"
  #include "ui/events/event.h"
  
  namespace ash {
  namespace {
  bool magnifier_key_scroller_enabled = false;
  }
  
  // static
  bool MagnifierKeyScroller::IsEnabled() {
    bool has_switch = base::CommandLine::ForCurrentProcess()->HasSwitch(
        switches::kAshEnableMagnifierKeyScroller);
  
    return (magnifier_key_scroller_enabled || has_switch) &&
           Shell::Get()->fullscreen_magnifier_controller()->IsEnabled();
  }
  
  // static
  void MagnifierKeyScroller::SetEnabled(bool enabled) {
    magnifier_key_scroller_enabled = enabled;
  }
  
  // static
  std::unique_ptr<ui::EventHandler> MagnifierKeyScroller::CreateHandler() {
    // Uses `new` due to private constructor.
    std::unique_ptr<KeyHoldDetector::Delegate> delegate(
        new MagnifierKeyScroller());
    return std::make_unique<KeyHoldDetector>(std::move(delegate));
  }
  
  bool MagnifierKeyScroller::ShouldProcessEvent(const ui::KeyEvent* event) const {
    return IsEnabled() && keyboard_util::IsArrowKeyCode(event->key_code());
  }
  
  bool MagnifierKeyScroller::IsStartEvent(const ui::KeyEvent* event) const {
    return event->type() == ui::ET_KEY_PRESSED &&
           event->flags() & ui::EF_SHIFT_DOWN;
  }
  
  bool MagnifierKeyScroller::ShouldStopEventPropagation() const {
    return true;
  }
  
  void MagnifierKeyScroller::OnKeyHold(const ui::KeyEvent* event) {
    FullscreenMagnifierController* controller =
        Shell::Get()->fullscreen_magnifier_controller();
    switch (event->key_code()) {
      case ui::VKEY_UP:
        controller->SetScrollDirection(FullscreenMagnifierController::SCROLL_UP);
        break;
      case ui::VKEY_DOWN:
        controller->SetScrollDirection(
            FullscreenMagnifierController::SCROLL_DOWN);
        break;
      case ui::VKEY_LEFT:
        controller->SetScrollDirection(
            FullscreenMagnifierController::SCROLL_LEFT);
        break;
      case ui::VKEY_RIGHT:
        controller->SetScrollDirection(
            FullscreenMagnifierController::SCROLL_RIGHT);
        break;
      default:
        NOTREACHED() << "Unknown keyboard_code:" << event->key_code();
    }
  }
  
  void MagnifierKeyScroller::OnKeyUnhold(const ui::KeyEvent* event) {
    FullscreenMagnifierController* controller =
        Shell::Get()->fullscreen_magnifier_controller();
    controller->SetScrollDirection(FullscreenMagnifierController::SCROLL_NONE);
  }
  
  MagnifierKeyScroller::MagnifierKeyScroller() = default;
  
  MagnifierKeyScroller::~MagnifierKeyScroller() = default;
  
  }  // namespace ash
  