/// <summary>
/// Arrange the children
/// </summary>
/// <param name="finalSize">Size available</param>
/// <returns>Size used</returns>
protected override Size ArrangeOverride(Size finalSize)
{
ItemsControl itemsControl = ItemsControl.GetItemsOwner(this);
TreeViewExItem treeViewItem = itemsControl as TreeViewExItem;
TreeViewEx treeView = itemsControl as TreeViewEx ?? treeViewItem.ParentTreeView;
IItemContainerGenerator generator = this.ItemContainerGenerator;
//Extent = finalSize;
bool foundVisibleItem = false;;
double currentY = 0;
if (treeView.IsVirtualizing)
{
for (int i = 0; i < itemsControl.Items.Count; i++)
{
FrameworkElement child = itemsControl.ItemContainerGenerator.ContainerFromIndex(i) as FrameworkElement;
if (foundVisibleItem)
{
if (child == null)
{
// other items are not visible / virtualized
break;
}
}
else
{
if (child != null)
{
// found first visible item
foundVisibleItem = true;
}
}
if (child != null)
{
child.Arrange(new Rect(-HorizontalOffset, currentY - VerticalOffset, finalSize.Width, child.DesiredSize.Height));
currentY += child.ActualHeight;
}
else
{
currentY += GetContainerHeightForItem(itemsControl, i);
}
}
// update average after arrange, because we have to use the same average as in measure for our calculation of currentY.
cachedSizes.Update();
}
else
{
for (int i = 0; i < itemsControl.Items.Count; i++)
{
UIElement child = itemsControl.ItemContainerGenerator.ContainerFromIndex(i) as UIElement;
if (child != null)
{
child.Arrange(new Rect(-HorizontalOffset, currentY - VerticalOffset, finalSize.Width, child.DesiredSize.Height));
}
currentY += child.DesiredSize.Height;
}
}
return(finalSize);
}
