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copied!<p>Look here: <a href="http://blogs.claritycon.com/blogs/lee_roth/default.aspx" rel="nofollow noreferrer">http://blogs.claritycon.com/blogs/lee_roth/default.aspx</a></p> <p>I make recycling the following way:</p> <p>In <code>OnItemsChanged</code>, I only call <code>RemoveInternalChildRange</code>:</p> <pre><code>protected override void OnItemsChanged(object sender, ItemsChangedEventArgs args) { switch (args.Action) { case NotifyCollectionChangedAction.Remove: case NotifyCollectionChangedAction.Replace: RemoveInternalChildRange(args.Position.Index, args.ItemUICount); break; case NotifyCollectionChangedAction.Move: RemoveInternalChildRange(args.OldPosition.Index, args.ItemUICount); break; } } </code></pre> <p>In Measure override, I first add new items, then I remove the old ones. <strong>If you use recycling you have to know that the new-Flag that you get by calling GenerateNext is also false if you get a recycled container.</strong></p> <p>Here we add new Items:</p> <pre><code>GeneratorPosition start = ItemContainerGenerator.GeneratorPositionFromIndex(iFirstItemIndex); int iChildIndex = (start.Offset == 0) ? start.Index : start.Index + 1; using (ItemContainerGenerator.StartAt(start, GeneratorDirection.Forward, true)) { for (int i = iFirstItemIndex; i <= iLastItemIndex; i++, iChildIndex++) { bool bNew; UIElement element = (UIElement)ItemContainerGenerator.GenerateNext(out bNew); //If we get a new instance if (bNew) { if (iChildIndex >= Children.Count) AddInternalChild(element); else InsertInternalChild(iChildIndex, element); ItemContainerGenerator.PrepareItemContainer(element); } //If we get a recycled element else if (!InternalChildren.Contains(element)) { InsertInternalChild(iChildIndex, element); ItemContainerGenerator.PrepareItemContainer(element); } element.Measure(...); } } </code></pre> <p>After adding Items we remove the old Items:</p> <pre><code>for (int i = Children.Count - 1; i >= 0; i--) { GeneratorPosition childGeneratorPosition = new GeneratorPosition(i, 0); int iIndex = ItemContainerGenerator.IndexFromGeneratorPosition(childGeneratorPosition); if (iIndex < iFirstItemIndex || iIndex > iLastItemIndex) { //remove() calls ItemContainerGenerator.remove() OR recycle(). Both works. remove(childGeneratorPosition, 1); RemoveInternalChildRange(i, 1); } } </code></pre> <p>I hope I could help you.</p>

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