text: // Copyright (c) 2011 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 UI_BASE_MODELS_MENU_MODEL_H_
  #define UI_BASE_MODELS_MENU_MODEL_H_
  #pragma once
  
  #include "base/memory/scoped_ptr.h"
  #include "base/string16.h"
  #include "ui/base/models/menu_model_delegate.h"
  #include "ui/base/ui_export.h"
  #include "ui/gfx/native_widget_types.h"
  
  class SkBitmap;
  
  namespace gfx {
  class Font;
  }
  
  namespace ui {
  
  class Accelerator;
  class ButtonMenuItemModel;
  
  // An interface implemented by an object that provides the content of a menu.
  class UI_EXPORT MenuModel {
   public:
    // The type of item.
    enum ItemType {
      TYPE_COMMAND,
      TYPE_CHECK,
      TYPE_RADIO,
      TYPE_SEPARATOR,
      TYPE_BUTTON_ITEM,
      TYPE_SUBMENU
    };
  
    virtual ~MenuModel() {}
  
    // Returns true if any of the items within the model have icons. Not all
    // platforms support icons in menus natively and so this is a hint for
    // triggering a custom rendering mode.
    virtual bool HasIcons() const = 0;
  
    // Returns the index of the first item. This is 0 for most menus except the
    // system menu on Windows. |native_menu| is the menu to locate the start index
    // within. It is guaranteed to be reset to a clean default state.  Some
    // callers of this method may pass NULL for native_menu.
    // IMPORTANT: If the model implementation returns something _other_ than 0
    //            here, it must offset the values for |index| it passes to the
    //            methods below by this number - this is NOT done automatically!
    virtual int GetFirstItemIndex(gfx::NativeMenu native_menu) const;
  
    // Returns the number of items in the menu.
    virtual int GetItemCount() const = 0;
  
    // Returns the type of item at the specified index.
    virtual ItemType GetTypeAt(int index) const = 0;
  
    // Returns the command id of the item at the specified index.
    virtual int GetCommandIdAt(int index) const = 0;
  
    // Returns the label of the item at the specified index.
    virtual string16 GetLabelAt(int index) const = 0;
  
    // Returns true if the menu item (label/icon) at the specified index can
    // change over the course of the menu's lifetime. If this function returns
    // true, the label and icon of the menu item will be updated each time the
    // menu is shown.
    virtual bool IsItemDynamicAt(int index) const = 0;
  
    // Returns the font use for the label at the specified index.
    // If NULL, then use default font.
    virtual const gfx::Font* GetLabelFontAt(int index) const;
  
    // Gets the acclerator information for the specified index, returning true if
    // there is a shortcut accelerator for the item, false otherwise.
    virtual bool GetAcceleratorAt(int index,
                                  ui::Accelerator* accelerator) const = 0;
  
    // Returns the checked state of the item at the specified index.
    virtual bool IsItemCheckedAt(int index) const = 0;
  
    // Returns the id of the group of radio items that the item at the specified
    // index belongs to.
    virtual int GetGroupIdAt(int index) const = 0;
  
    // Gets the icon for the item at the specified index, returning true if there
    // is an icon, false otherwise.
    virtual bool GetIconAt(int index, SkBitmap* icon) = 0;
  
    // Returns the model for a menu item with a line of buttons at |index|.
    virtual ButtonMenuItemModel* GetButtonMenuItemAt(int index) const = 0;
  
    // Returns the enabled state of the item at the specified index.
    virtual bool IsEnabledAt(int index) const = 0;
  
    // Returns true if the menu item is visible.
    virtual bool IsVisibleAt(int index) const;
  
    // Returns the model for the submenu at the specified index.
    virtual MenuModel* GetSubmenuModelAt(int index) const = 0;
  
    // Called when the highlighted menu item changes to the item at the specified
    // index.
    virtual void HighlightChangedTo(int index) = 0;
  
    // Called when the item at the specified index has been activated.
    virtual void ActivatedAt(int index) = 0;
  
    // Called when the item has been activated with given event flags.
    // (for the case where the activation involves a navigation).
    // |event_flags| is a bit mask of ui::EventFlags.
    virtual void ActivatedAt(int index, int event_flags);
  
    // Called when the menu is about to be shown.
    virtual void MenuWillShow() {}
  
    // Called when the menu has been closed.
    virtual void MenuClosed() {}
  
    // Set the MenuModelDelegate. Owned by the caller of this function.
    virtual void SetMenuModelDelegate(MenuModelDelegate* delegate) = 0;
  
    // Retrieves the model and index that contains a specific command id. Returns
    // true if an item with the specified command id is found. |model| is inout,
    // and specifies the model to start searching from.
    static bool GetModelAndIndexForCommandId(int command_id, MenuModel** model,
                                             int* index);
  };
  
  }  // namespace ui
  
  #endif  // UI_BASE_MODELS_MENU_MODEL_H_
  