ash/shelf/back_button.h

// Copyright 2017 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef ASH_SHELF_BACK_BUTTON_H_
#define ASH_SHELF_BACK_BUTTON_H_

#include <memory>

#include "ash/ash_export.h"
#include "ash/shelf/shelf_button_delegate.h"
#include "ash/shelf/shelf_control_button.h"
#include "ui/accessibility/ax_enums.mojom-forward.h"
#include "ui/base/metadata/metadata_header_macros.h"

namespace ash {

class ShelfButtonDelegate;

// The back button shown on the shelf when tablet mode is enabled. Its opacity
// and visiblity are handled by its parent, ShelfView, to ensure the fade
// in/out of the icon matches the movement of ShelfView's items.
class ASH_EXPORT BackButton : public ShelfControlButton,
                              public ShelfButtonDelegate {
  METADATA_HEADER(BackButton, ShelfControlButton)

 public:
  explicit BackButton(Shelf* shelf);

  BackButton(const BackButton&) = delete;
  BackButton& operator=(const BackButton&) = delete;

  ~BackButton() override;

  // Called when a locale change is detected. Updates the button tooltip and
  // accessible name.
  void HandleLocaleChange();

  // views::Button:
  void PaintButtonContents(gfx::Canvas* canvas) override;

  // views::View:
  void OnThemeChanged() override;

  // ShelfButtonDelegate:
  void OnShelfButtonAboutToRequestFocusFromTabTraversal(ShelfButton* button,
                                                        bool reverse) override;

  void ButtonPressed(views::Button* sender,
                     const ui::Event& event,
                     views::InkDrop* ink_drop) override;

 private:
  void OnAXNameChanged(ax::mojom::StringAttribute attribute,
                       const std::optional<std::string>& name);

  base::CallbackListSubscription ax_name_change_subscription_;
};

}  // namespace ash

#endif  // ASH_SHELF_BACK_BUTTON_H_