internal ScrollTracingInfo(ScrollTracer tracer, int depth, FrameworkElement owner, VirtualizingStackPanel parent, object parentItem, int itemIndex)
{
ScrollTracer = tracer;
Depth = depth;
Owner = owner;
Parent = parent;
ParentItem = parentItem;
ItemIndex = itemIndex;
}
internal static void ConfigureTracing(VirtualizingStackPanel vsp,
DependencyObject itemsOwner,
object parentItem,
ItemsControl itemsControl)
{
Debug.Assert(!IsConfigured(vsp));
ScrollTracer tracer = null;
if (itemsControl.Name == _targetName)
{
SetTarget(itemsControl, overwriteExistingTarget:false);
}
ScrollTracingInfo sti = _nullInfo; // default - do nothing
if (parentItem == vsp)
{
// top level VSP
if (itemsOwner == _target)
{
tracer = new ScrollTracer(itemsControl, vsp);
}
if (tracer != null)
{
sti = new ScrollTracingInfo(tracer, 0, itemsOwner as FrameworkElement, null, null, 0);
}
}
else
{
// inner VSP
VirtualizingStackPanel parent = VisualTreeHelper.GetParent(itemsOwner) as VirtualizingStackPanel;
if (parent != null)
{
ScrollTracingInfo parentInfo = ScrollTracingInfoField.GetValue(parent);
if (parentInfo != null)
{
tracer = parentInfo.ScrollTracer;
if (tracer != null)
{
ItemContainerGenerator generator = parent.ItemContainerGenerator as ItemContainerGenerator;
int itemIndex = (generator != null) ? generator.IndexFromContainer(itemsOwner, returnLocalIndex:true) : -1;
sti = new ScrollTracingInfo(tracer, parentInfo.Depth + 1, itemsOwner as FrameworkElement, parent, parentItem, itemIndex);
}
}
}
}
ScrollTracingInfoField.SetValue(vsp, sti);
}
