/// <summary>
/// Update the virtualization of the scrollviewer in <see cref="Timer.Tag"/>
/// </summary>
/// <param name="sender"><see cref="Timer"/></param>
/// <param name="e"></param>
private static void OnTimerElapsed(object sender = null, EventArgs e = null)
{
LimeMsg.Debug("DataVirtualization OnTimerElapsed");
Timer.Stop();
var wxscroll = (ScrollViewer)Timer.Tag;
Timer.Tag = null;
var reflist = References[wxscroll];
// TODO: optimize to take into account what was visible previously to not loop all over again
foreach (var wref in reflist)
{
if (!wref.IsAlive || !(wref.Target is ItemsControl wxctrl))
{
continue;
}
var itemgen = wxctrl.ItemContainerGenerator;
var itemcnt = itemgen.Items.Count;
int startSelected = -1;
int endSelected = -1;
var rangeSelected = new List <ItemIndexRange>();
int startVisible = -1;
int endVisible = -1;
var rangeVisible = new List <ItemIndexRange>();
for (int i = 0; i < itemcnt; i++)
{
if (!(itemgen.ContainerFromIndex(i) is FrameworkElement wxitem))
{
continue;
}
if (wxitem.DataContext is IItemsRangeInfo)
{
// Detect selected items
if (wxitem.IsFocused)
{
if (startSelected == -1)
{
startSelected = i;
}
endSelected = i;
}
else if (Selector.GetIsSelected(wxitem))
{
if (startSelected == -1)
{
startSelected = i;
}
endSelected = i;
}
else if (startSelected != -1)
{
rangeSelected.Add(new ItemIndexRange(startSelected, (uint)(endSelected - startSelected + 1)));
startSelected = -1;
}
// Detect visible items
if (WPF.IsFullyOrPartiallyVisible(wxitem, wxscroll))
{
if (startVisible == -1)
{
startVisible = i;
}
endVisible = i;
}
else if (startVisible != -1)
{
rangeVisible.Add(new ItemIndexRange(startVisible, (uint)(endVisible - startVisible + 1)));
startVisible = -1;
}
}
}
var target = GetTarget(wxctrl);
// TODO: handle selection
if (target is IItemsRangeInfo rinfo)
{
if (startVisible != -1)
{
rangeVisible.Add(new ItemIndexRange(startVisible, (uint)(endVisible - startVisible + 1)));
startVisible = -1;
}
if (rangeVisible.Count > 0)
{
rinfo.RangesChanged(rangeVisible[0], new ReadOnlyCollection <ItemIndexRange>(rangeVisible));
}
}
}
}
