private void Initialize()
{
_itemsControl = ItemsControl.GetItemsOwner(this);
_itemsGenerator = (IRecyclingItemContainerGenerator) ItemContainerGenerator;
InvalidateMeasure();
}
protected override void OnItemsChanged(object sender, ItemsChangedEventArgs args)
{
switch (args.Action)
{
case NotifyCollectionChangedAction.Remove:
case NotifyCollectionChangedAction.Replace:
RemoveInternalChildRange(args.Position.Index, args.ItemUICount);
break;
case NotifyCollectionChangedAction.Move:
if (args.Position.Index < 0)
{
InvalidateMeasure();
ScrollOwner?.InvalidateScrollInfo();
SetVerticalOffset(0);
}
else
{
RemoveInternalChildRange(args.OldPosition.Index, args.ItemUICount);
}
break;
case NotifyCollectionChangedAction.Reset:
itemsControl = ItemsControl.GetItemsOwner(this);
generator = (IRecyclingItemContainerGenerator)ItemContainerGenerator;
InvalidateMeasure();
ScrollOwner?.InvalidateScrollInfo();
SetVerticalOffset(0);
break;
}
}
private void Initialize()
{
_itemsControl = ItemsControl.GetItemsOwner(this);
_itemsGenerator = (IRecyclingItemContainerGenerator)ItemContainerGenerator;
InvalidateMeasure();
}
private void Initialize()
{
_itemsControl = ItemsControl.GetItemsOwner(this);
#if NETFX_CORE
_itemsGenerator = ItemContainerGenerator;
#else
_itemsGenerator = (IRecyclingItemContainerGenerator)ItemContainerGenerator;
#endif
InvalidateMeasure();
}
//
// Helper Methods
//
void RemoveUnusedContainers(int first, int count)
{
IRecyclingItemContainerGenerator generator = ItemContainerGenerator as IRecyclingItemContainerGenerator;
ItemsControl owner = ItemsControl.GetItemsOwner(this);
VirtualizationMode mode = GetVirtualizationMode(this);
CleanUpVirtualizedItemEventArgs args;
int last = first + count - 1;
GeneratorPosition pos;
int item;
//Console.WriteLine ("VSP.RemoveUnusedContainers ({0}, {1});", first, count);
pos = new GeneratorPosition(Children.Count - 1, 0);
while (pos.Index >= 0)
{
item = generator.IndexFromGeneratorPosition(pos);
if (item < first || item > last)
{
//Console.WriteLine ("\tRemoving item[{0}] (child #{1})", item, pos.Index);
args = new CleanUpVirtualizedItemEventArgs(Children[pos.Index], owner.Items[item]);
OnCleanUpVirtualizedItem(args);
if (!args.Cancel)
{
RemoveInternalChildRange(pos.Index, 1);
if (mode == VirtualizationMode.Recycling)
{
generator.Recycle(pos, 1);
}
else
{
generator.Remove(pos, 1);
}
}
}
pos.Index--;
}
}
//
// Helper Methods
//
void RemoveUnusedContainers(int first, int count)
{
IRecyclingItemContainerGenerator generator = ItemContainerGenerator as IRecyclingItemContainerGenerator;
ItemsControl owner = ItemsControl.GetItemsOwner(this);
VirtualizationMode mode = GetVirtualizationMode(this);
int last = first + count - 1;
GeneratorPosition pos;
int item;
//Console.WriteLine ("VSP.RemoveUnusedContainers ({0}, {1});", first, count);
pos = new GeneratorPosition(Children.Count - 1, 0);
while (pos.Index >= 0)
{
item = generator.IndexFromGeneratorPosition(pos);
// Note: we should not remove the child if it is an item of its owner ItemsControl be
// we remove it anyway because ScrollContentPresenter does not properly work with an
// external IScrollInfo which leads to layout issues
if ((item < first || item > last) &&
/*!((IGeneratorHost)owner).IsItemItsOwnContainer(owner.Items[item]) &&*/
NotifyCleanupItem(Children[pos.Index], owner))
{
RemoveInternalChildRange(pos.Index, 1);
if (mode == VirtualizationMode.Recycling &&
!((IGeneratorHost)owner).IsItemItsOwnContainer(owner.Items[item]))
{
generator.Recycle(pos, 1);
}
else
{
generator.Remove(pos, 1);
}
}
pos.Index--;
}
}
protected override Size MeasureOverride(Size availableSize)
{
UpdateScrollInfo(availableSize);
// This is for weird edge case where Measuring can occur and OnItemsChanged was not called by WPF first
if (ItemWidth == 0)
{
itemsControl = ItemsControl.GetItemsOwner(this);
generator = (IRecyclingItemContainerGenerator)ItemContainerGenerator;
using (generator.StartAt(generator.GeneratorPositionFromIndex(0), GeneratorDirection.Forward, true))
{
UIElement child = generator.GenerateNext(out var newlyRealized) as UIElement;
if (child != null)
{
AddInternalChild(child);
generator.PrepareItemContainer(child);
child.Measure(new Size(double.PositiveInfinity, double.PositiveInfinity));
UpdateScrollInfo(availableSize);
RemoveInternalChildRange(0, 1);
}
}
}
GetVisibleRange(out var firstItemIndex, out var lastItemIndex);
if (lastItemIndex < 0)
{
return(new Size(0, 0));
}
var startPos = generator.GeneratorPositionFromIndex(firstItemIndex);
var childIndex = (startPos.Offset == 0) ? startPos.Index : startPos.Index + 1;
using (generator.StartAt(startPos, GeneratorDirection.Forward, true))
{
for (int itemIndex = firstItemIndex; itemIndex <= lastItemIndex; ++itemIndex, ++childIndex)
{
UIElement child = generator.GenerateNext(out var newlyRealized) as UIElement;
if (child == null)
{
continue;
}
if (newlyRealized)
{
if (childIndex >= InternalChildren.Count)
{
AddInternalChild(child);
}
else
{
InsertInternalChild(childIndex, child);
}
generator.PrepareItemContainer(child);
}
else if (!InternalChildren.Contains(child))
{
InsertInternalChild(childIndex, child);
ItemContainerGenerator.PrepareItemContainer(child);
}
child.Measure(new Size(double.PositiveInfinity, double.PositiveInfinity));
}
}
CleanUpItems(firstItemIndex, lastItemIndex);
if (availableSize.Width == double.PositiveInfinity || availableSize.Height == double.PositiveInfinity)
{
return(GetExtent());
}
else
{
return(availableSize);
}
}
private void Initialize()
{
_itemsControl = ItemsControl.GetItemsOwner(this);
_itemsGenerator = (IRecyclingItemContainerGenerator)ItemContainerGenerator;
_itemsControl.LostFocus += _itemsControl_LostFocus;
_itemsControl.LostKeyboardFocus += _itemsControl_LostKeyboardFocus;
InvalidateMeasure();
}
