Store AppItems as pages in AppListModel.

ui/app_list/app_list_model.h

Index: ui/app_list/app_list_model.h
diff --git a/ui/app_list/app_list_model.h b/ui/app_list/app_list_model.h
index 2238941415820e1b84f7fa516dea7fe42b226581..018954ebc86edcef107b61085b7503471923be77 100644
--- a/ui/app_list/app_list_model.h
+++ b/ui/app_list/app_list_model.h
@@ -22,8 +22,8 @@ class AppListModelObserver;
 class SearchBoxModel;
 class SearchResult;
 
-// Master model of app list that consists of three sub models: Apps,
-// SearchBoxModel and SearchResults. The Apps sub model owns a list of
+// Master model of app list that consists of three sub models: AppItems,
+// SearchBoxModel and SearchResults. The AppItems sub model owns a list of
 // AppListItemModel and is displayed in the grid view. SearchBoxModel is
 // the model for SearchBoxView. SearchResults owns a list of SearchResult.
 class APP_LIST_EXPORT AppListModel {
@@ -51,7 +51,7 @@ class APP_LIST_EXPORT AppListModel {
     STATUS_SYNCING,  // Syncing apps or installing synced apps.
   };
 
-  typedef ui::ListModel<AppListItemModel> Apps;
+  typedef ui::ListModel<AppListItemModel> AppItems;
   typedef ui::ListModel<SearchResult> SearchResults;
   typedef std::vector<User> Users;
 
@@ -68,15 +68,44 @@ class APP_LIST_EXPORT AppListModel {
   // Find item matching |id|. NOTE: Requires a linear search.
   AppListItemModel* FindItem(const std::string& id);
 
-  // Adds |item| to |apps_|. Takes ownership of |item|. Uses item->SortOrder()
-  // to insert in the correct place. TODO(stevenjb): Use synced app list order
-  // instead of SortOrder when available: crbug.com/305024.
-  void AddItem(AppListItemModel* item);
+  // Returns the item at |page_idx| and |item_idx| or NULL.
+  AppListItemModel* GetItemAt(size_t page_idx, size_t item_idx);

[xiyuan, 2013/10/18 23:04:08]

Propose to use page id instead of index. It would be easier to use page id to
track the page than index. Maybe put a TODO if we don't get to it in this CL.

[stevenjb, 2013/10/19 01:04:43]

I'll think about that. I can see where it makes sense, but it might also make
the View implementation more difficult. Maybe we'll want both?

 
-  // Finds |item| in |apps_| and deletes it.
+  // Adds |item| to a page. Takes ownership of |item|. Uses
+  // item->SortOrder() to insert in the correct page and position.
+  // Returns which page the item was added to.
+  // TODO(stevenjb): Use synced app list order instead of SortOrder.
+  // crbug.com/305024.
+  size_t AddItem(AppListItemModel* item);
+
+  // Similar to AddItem, but adds the item to a specific page. If the page is
+  // full the item will be added to the end of the page and the last item in
+  // the page will be pushed to the next page. Returns the index of the page
+  // that the item was added to (|page_idx| or |page_idx|  + 1). |page_idx| must
+  // be <= the number of pages, i.e. at most one new page will be added.
+  size_t AddItemToPage(AppListItemModel* item, size_t page_idx);
+
+  // Finds |item| in the model and deletes it.
   void DeleteItem(const std::string& id);
 
-  Apps* apps() { return apps_.get(); }
+  // Deletes item at |item_idx| from page |page_idx|.
+  void DeleteItemAt(size_t page_idx, size_t item_idx);
+
+  // Move item at |item_idx| in |page_idx| to |target_index|
+  // in |target_page_idx|.
+  void MoveItem(size_t page_idx, size_t item_idx,
+                size_t target_page_idx, size_t target_item_idx);
+
+  // Returns the number of apps per page.
+  static size_t GetNumAppsPerPage();
+
+  // Returns the number of app pages.
+  size_t GetNumAppPages() const;
+
+  // Returns a const reference to the items at page |page_idx| which must be
+  // less than GetAppPages().
+  const AppItems& GetAppItemsForPage(size_t page_idx) const;
+
   SearchBoxModel* search_box() { return search_box_.get(); }
   SearchResults* results() { return results_.get(); }
   Status status() const { return status_; }
@@ -86,8 +115,27 @@ class APP_LIST_EXPORT AppListModel {
     return users_;
   }
 
- private:
-  scoped_ptr<Apps> apps_;
+private:
+  class ItemPage;
+
+  // Gets the list of items fpr |page_idx| from item_pages_ and checks ranges.
+  AppItems* app_items(size_t page_idx);
+
+  // Creates/removes a page of items.
+  void AddPage();
+  void RemovePage(size_t idx);
+
+  // Adds |item| to page |page_idx| at |item_idx| and handles overflow.
+  // Returns the page index for |item| which will differ from |page_idx| only
+  // if |item_idx| == GetNumAppsPerPage().
+  size_t AddItemToPageAtIndex(AppListItemModel* item,
+                              size_t page_idx, size_t item_idx);
+
+  // Sets the postion of |item| based on its new index.
+  void SetItemPosition(AppListItemModel* item,
+                       size_t page_idx, size_t item_idx);
+
+  ScopedVector<ItemPage> item_pages_;
 
   scoped_ptr<SearchBoxModel> search_box_;
   scoped_ptr<SearchResults> results_;