ash/system/overview/overview_button_tray.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_SYSTEM_OVERVIEW_OVERVIEW_BUTTON_TRAY_H_
#define ASH_SYSTEM_OVERVIEW_OVERVIEW_BUTTON_TRAY_H_

#include "ash/ash_export.h"
#include "ash/session/session_observer.h"
#include "ash/shell_observer.h"
#include "ash/system/tray/tray_background_view.h"
#include "ash/wm/tablet_mode/tablet_mode_observer.h"
#include "base/macros.h"
#include "ui/events/event_constants.h"

namespace views {
class ImageView;
}

namespace ash {

// Status area tray for showing a toggle for Overview Mode. Overview Mode
// is equivalent to OverviewController being in selection mode.
// This hosts a ShellObserver that listens for the activation of Maximize Mode
// This tray will only be visible while in this state. This tray does not
// provide any bubble view windows.
class ASH_EXPORT OverviewButtonTray : public TrayBackgroundView,
                                      public SessionObserver,
                                      public ShellObserver,
                                      public TabletModeObserver {
 public:
  // Second taps within this time will be counted as double taps. Use this
  // instead of ui::Event's click_count and tap_count as those have a minimum
  // time bewtween events before the second tap counts as a double tap.
  // TODO(crbug.com/817883): We should the gesture detector double tap time or
  // overview enter animation time, once ux decides which one to match (both are
  // 300ms currently).
  static constexpr base::TimeDelta kDoubleTapThresholdMs =
      base::TimeDelta::FromMilliseconds(300);

  explicit OverviewButtonTray(Shelf* shelf);
  ~OverviewButtonTray() override;

  // Updates the tray's visibility based on the LoginStatus and the current
  // state of TabletMode
  virtual void UpdateAfterLoginStatusChange(LoginStatus status);

  // views::Button:
  void OnGestureEvent(ui::GestureEvent* event) override;

  // ActionableView:
  bool PerformAction(const ui::Event& event) override;

  // SessionObserver:
  void OnSessionStateChanged(session_manager::SessionState state) override;

  // ShellObserver:
  void OnOverviewModeStarting() override;
  void OnOverviewModeEnded() override;

  // TabletModeObserver:
  void OnTabletModeEventsBlockingChanged() override;

  // TrayBackgroundView:
  void ClickedOutsideBubble() override;
  base::string16 GetAccessibleNameForTray() override;
  void HideBubbleWithView(const TrayBubbleView* bubble_view) override;

 private:
  friend class OverviewButtonTrayTest;

  // Sets the icon to visible if tablet mode is enabled and
  // OverviewController::CanSelect.
  void UpdateIconVisibility();

  // Weak pointer, will be parented by TrayContainer for its lifetime.
  views::ImageView* icon_;

  ScopedSessionObserver scoped_session_observer_;

  // Stores the timestamp of the last tap event time that happened while not
  // in overview mode. Used to check for double taps, which invoke quick switch.
  base::Optional<base::TimeTicks> last_press_event_time_;

  DISALLOW_COPY_AND_ASSIGN(OverviewButtonTray);
};

}  // namespace ash

#endif  // ASH_SYSTEM_OVERVIEW_OVERVIEW_BUTTON_TRAY_H_