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POWPF item container recycling
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copied!<p>I want to implement a custom <code>Canvas</code> that recycles containers when used as an <code>ItemsPanel</code>. So I derived from <code>VirtualizingPanel</code> and override the <code>ArrangeOverride</code> and <code>MeasureOverride</code>. I am doing the generation in <code>MeasureOverride</code> like this:</p> <pre><code>var children = base.InternalChildren; var itemsControl = ItemsControl.GetItemsOwner(this); var itemsCount = itemsControl.Items.Count; IItemContainerGenerator generator = itemsControl.ItemContainerGenerator; var startPos = generator.GeneratorPositionFromIndex(0); using (generator.StartAt(startPos, GeneratorDirection.Forward, true)) { for (int i = 0; i < itemsCount; i++) { bool isNewlyRealized; var child = generator.GenerateNext(out isNewlyRealized) as UIElement; if (isNewlyRealized) { base.AddInternalChild(child); generator.PrepareItemContainer(child); } child.Measure(constraint); } } </code></pre> <p>What I don't know is how to make the recycling. I tried something like the following:</p> <pre><code>protected override void OnItemsChanged(object sender, ItemsChangedEventArgs e) { switch (e.Action) { case NotifyCollectionChangedAction.Remove: case NotifyCollectionChangedAction.Replace: case NotifyCollectionChangedAction.Move: IRecyclingItemContainerGenerator generator = ItemsControl.GetItemsOwner(this).ItemContainerGenerator; generator.Recycle(e.Position, e.ItemUICount); RemoveInternalChildRange(e.Position.Index, e.ItemUICount); break; } } </code></pre> <p>But it doesn't work. Any idea how to do this?</p>

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