Implemented loading menu item (#290)

Author: TheNinth7

source/main/user-interface/features/sitemap/base/menu-items/WidgetMenuItem.mc

@@ -122,7 +122,13 @@ class WidgetMenuItem extends StructuredMenuItem {
     // do not need to override this method.
     public function onSelect() as Boolean { 
         if( _page != null ) {
-            ViewStack.pushView( _page, PageMenuDelegate.get(), WatchUi.SLIDE_LEFT );
+            var page = _page;
+            Logger.debug( "WidgetMenuItem.onSelect: pushing page" );
+            // Pushing a CustomMenu with no menu items leads to weird behavior.
+            // Therefore ensureItems() adds a LoadingMenuItem if no other
+            // items are present at this time. See ensureItems() for details.
+            page.ensureItems();
+            ViewStack.pushView( page, PageMenuDelegate.get(), WatchUi.SLIDE_LEFT );
             return true;
         } else {
             if( ! ConnectionManager.get().isConnected() ) {

source/main/user-interface/features/sitemap/pages/base/BasePageMenu.mc

@@ -78,7 +78,7 @@ class BasePageMenu extends BaseMenu {
 
         // Create a menu item for each widget.
         if( processingMode == PROCESSING_TOP_LEVEL_SYNC ) {
-            // Logger.debug( "BasePageMenu.initialize: synchronous processing" );
+            Logger.debug( "BasePageMenu.initialize: synchronous processing" );
             // In top-level sync mode, menu items are created synchronously.
             // The next level is then initialized in PROCESSING_ASYNC_AFTER_SYNC mode.
             for( var i = 0; i < widgets.size(); i++ ) {

source/main/user-interface/features/sitemap/pages/base/UpdateTasks.mc

@@ -65,8 +65,9 @@ class AddOrUpdateMenuItemTask extends BaseSitemapProcessorTask {
         } else {
             // If the item is found, we check if the type of the menu
             // item is the same or has changed
-            var item = _pageMenu.getItem( _index ) as WidgetMenuItem;
-            if( item.isMyType( _sitemapWidget ) ) {
+            var item = _pageMenu.getItem( _index );
+
+            if( item instanceof WidgetMenuItem && item.isMyType( _sitemapWidget ) ) {
                 // If the type matches, the menu item is updated.
                 // However, if the item was updated internally within the configured
                 // post-command hold time, the update is ignored. Internal updates are used
@@ -79,15 +80,21 @@ class AddOrUpdateMenuItemTask extends BaseSitemapProcessorTask {
                     item.updateWidget( _sitemapWidget );
                 }
             } else {
-                // If the type is not the same, we create a new item
-                // and replace the existing menu item with it
+                // If the item is not a WidgetMenuItem or the widget type
+                // does not match, create a new item and replace the
+                // existing menu item.
                 var newItem = MenuItemFactory.createMenuItem( 
                     _sitemapWidget, 
                     _pageMenu,
                     BasePageMenu.PROCESSING_ASYNC
                 );
 
-                if( item.hasPage() || newItem.hasPage() ) {
+                // If either the previous or the new menu item has sub-pages,
+                // invalidate the structure. This causes the app to jump back
+                // to the homepage menu.
+                if( ( item instanceof WidgetMenuItem && item.hasPage() ) 
+                    || newItem.hasPage() 
+                ) {
                     _pageMenu.invalidateStructure();
                     // Logger.debug( "AddOrUpdateMenuItemTask: page '" + _pageMenu.getTitle() + "' invalid because item '" + item.getLabel() + "' changed type from/to page" );
                 }

source/main/user-interface/features/sitemap/pages/page/PageMenu.mc

@@ -26,6 +26,31 @@ class PageMenu extends BasePageMenu {
         _weakParent = parent.weak();
     }
 
+    // Overrides the base class addItem() to remove the loading
+    // item if present.
+    public function addItem( item as CustomMenuItem ) as Void {
+        Logger.debug( "PageMenu.addItem" );
+        if( getItem( 0 ) instanceof LoadingMenuItem ) {
+            Logger.debug( "PageMenu.addItem: removing loading item" );
+            deleteItem( 0 );
+        }
+        BaseMenu.addItem( item );
+    }
+
+    // Checks if menu items are present and adds the loading menu item
+    // if none exist.
+    // Pushing an empty menu as a view leads to weird side effects,
+    // therefore this is called every time before a page menu is pushed.
+    // The loading menu item is removed when the first real item
+    // is added. See addItem() above.
+    public function ensureItems() as Void {
+        Logger.debug( "PageMenu.ensureItems" );
+        if( getItemCount() < 1 ) {
+            Logger.debug( "PageMenu.ensureItems: adding loading item" );
+            BasePageMenu.addItem( new LoadingMenuItem() );
+        }
+    }
+
     // See BasePageMenu.invalidateStructure for details
     public function invalidateStructure() as Void {
         var parent = _weakParent.get() as BasePageMenu?;

source/main/user-interface/features/sitemap/widgets/dummy/LoadingMenuItem.mc

@@ -0,0 +1,10 @@
+import Toybox.Lang;
+import Toybox.WatchUi;
+
+class LoadingMenuItem extends StructuredMenuItem {
+    
+    // Constructor
+    public function initialize() {
+        StructuredMenuItem.initialize( { :label => "Loading..." } );
+    }
+}