System.Windows.Controls.ItemContainerGenerator.GenerateNext C# (CSharp) Method

		internal DependencyObject GenerateNext (out bool isNewlyRealized)
		{
			int index;
			// This is relative to the realised elements.
			int startAt = GenerationState.Position.Index;
			if (startAt == -1) {
				if (GenerationState.Position.Offset < 0)
					index = Owner.Items.Count + GenerationState.Position.Offset;
				else if (GenerationState.Position.Offset == 0)
					index = 0;
				else
					index = GenerationState.Position.Offset - 1;
			} else if (startAt >= 0 && startAt < RealizedElements.Count) {
				// We're starting relative to an already realised element
				index = RealizedElements [startAt] + GenerationState.Position.Offset;
			} else {
				index = -1;
			}

			bool alreadyRealized = RealizedElements.Contains (index);
			if (!GenerationState.AllowStartAtRealizedItem && alreadyRealized && GenerationState.Position.Offset == 0) {
				index += GenerationState.Step;
				alreadyRealized = RealizedElements.Contains (index);
			}
			
			if (index < 0 || index >= Owner.Items.Count) {
				isNewlyRealized = false;
				return null;
			}
			
			if (alreadyRealized) {
				GenerationState.Position = new GeneratorPosition (RealizedElements.IndexOf (index), GenerationState.Step);
				isNewlyRealized = false;
				
				return ContainerIndexMap [index];
			}
			
			DependencyObject container;
			var item = Owner.Items [index];
			if (Owner.IsItemItsOwnContainer (item)) {
				container = (DependencyObject) item;
				isNewlyRealized = true;
			} else {
				if (Cache.Count == 0) {
					container = Owner.GetContainerForItem ();
					isNewlyRealized = true;
				} else {
					container = Cache.Dequeue ();
					isNewlyRealized = false;
				}
				
				ContentControl c = container as ContentControl;
				if (c != null)
					c.ContentSetsParent = false;
			}

			FrameworkElement f = container as FrameworkElement;
			if (f != null && !(item is UIElement))
				f.DataContext = item;

			RealizedElements.Add (index);
			ContainerIndexMap.Add (container, index);
			DependencyObject cc;
			ContainerItemMap.Add (container, item);
			
			GenerationState.Position = new GeneratorPosition (RealizedElements.IndexOf (index), GenerationState.Step);
			return container;
		}

        void AddItemsToPresenter(GeneratorPosition position, int count)
        {
            if (_presenter == null || _presenter._elementRoot == null || _presenter._elementRoot is VirtualizingPanel)
            {
                return;
            }

            Panel panel    = _presenter._elementRoot;
            int   newIndex = ItemContainerGenerator.IndexFromGeneratorPosition(position);

            using (var p = ItemContainerGenerator.StartAt(position, GeneratorDirection.Forward, true))
                for (int i = 0; i < count; i++)
                {
                    var item = Items [newIndex + i];
                    DependencyObject container = null;

                    bool fresh;
                    container = ItemContainerGenerator.GenerateNext(out fresh);
                    ContentControl c = container as ContentControl;
                    if (c != null)
                    {
                        c.ContentSetsParent = false;
                    }

                    FrameworkElement f = container as FrameworkElement;
                    if (f != null && !(item is FrameworkElement))
                    {
                        f.DataContext = item;
                    }

                    panel.Children.Insert(newIndex + i, (UIElement)container);
                    ItemContainerGenerator.PrepareItemContainer(container);
                }
        }