/// <summary>
/// Returns the size of the container for a given item. The size can come from the container, a lookup, or a guess depending
/// on the virtualization state of the item.
/// </summary>
/// <returns>The cached or estimated size.</returns>
/// <remarks>This estimation looks if the given index is cached. If not it returns the maximum height of the cached
/// containers. If no container is cached, returns zero.
/// One case it fails is, if all cached items are bigger
/// than the estimated items. This leads to jumping scrollbars. The effect is not that bad, if many items will be visualized.</remarks>
private double GetCachedOrEstimatedHeight(TreeViewEx tree, int level)
{
if (cachedSizes.ContainsItems(0))
{
return(cachedSizes.GetEstimate(0));
}
return(tree.cachedSizes.GetEstimate(level));
}
