// ----------------------------------------------------------------------------------------------
#region Class functions
private static void TargetChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
var wxthis = (ItemsControl)d;
if (e.OldValue is IItemsRangeInfo rinfo)
{
rinfo.Close();
}
var enable = e.NewValue is IItemsRangeInfo || e.NewValue is ISelectionInfo;
if (enable)
{
// Lazy declaration of Timer
if (Timer == null)
{
Timer = new DispatcherTimer();
Timer.Tick += OnTimerElapsed;
}
wxthis.Loaded += OnLoaded;
wxthis.Unloaded += OnUnloaded;
}
else
{
wxthis.Loaded -= OnLoaded;
wxthis.Unloaded -= OnUnloaded;
}
ScrollViewer wxscroll;
if (wxthis is ListBox)
{
wxscroll = WPF.FindFirstChild <ScrollViewer>(wxthis);
}
else
{
wxscroll = WPF.FindFirstParent <ScrollViewer>(wxthis);
}
if (References == null)
{
References = new Dictionary <ScrollViewer, List <WeakReference> >();
}
if (References.TryGetValue(wxscroll, out var reflist))
{
// Remove dead references
for (int i = 0; i < reflist.Count; i++)
{
var wref = reflist[i];
if (!wref.IsAlive || wref.Target == wxthis)
{
reflist.RemoveAt(i);
i--;
}
}
}
else if (enable)
{
reflist = new List <WeakReference>();
References.Add(wxscroll, reflist);
}
if (enable)
{
reflist.Add(new WeakReference(wxthis));
if (reflist.Count == 1)
{
wxscroll.ScrollChanged += OnScrollChanged;
}
}
else if (reflist == null || reflist.Count == 0)
{
wxscroll.ScrollChanged -= OnScrollChanged;
}
}
