protected internal override void OnQueryItems(VirtualPage page, AsyncQueryInfo queryInfo)
{
base.OnQueryItems(page, queryInfo);
DataGridVirtualizingQueryableCollectionViewGroup collectionViewGroup =
this.GetLinkedCollectionViewGroup(page.ParentVirtualList) as DataGridVirtualizingQueryableCollectionViewGroup;
IQueryable queryableToUse;
int virtualItemCount = collectionViewGroup.VirtualItemCount;
bool queryableIsReversed;
if ((!m_supportsPrimaryKeyOptimizations) || (queryInfo.StartIndex < (virtualItemCount / 2)))
{
queryableIsReversed = false;
queryableToUse = collectionViewGroup.Queryable.Slice(queryInfo.StartIndex, queryInfo.RequestedItemCount);
}
else
{
queryableIsReversed = true;
int reversedStartIndex = virtualItemCount - (queryInfo.StartIndex + queryInfo.RequestedItemCount);
queryableToUse = collectionViewGroup.ReversedQueryable.Slice(reversedStartIndex, queryInfo.RequestedItemCount);
}
System.Threading.ThreadPool.QueueUserWorkItem(new System.Threading.WaitCallback(this.AsyncGatherItems), new object[] { queryInfo, queryableToUse, queryableIsReversed });
}
public DataGridVirtualizingQueryableCollectionViewGroup(
object name,
int initialItemsCount,
int startGlobalIndex,
DataGridVirtualizingQueryableCollectionViewGroup parent,
int level,
bool isBottomLevel)
: base(name, initialItemsCount, startGlobalIndex, parent, level, isBottomLevel)
{
}
protected override int OnQueryItemCountCore(VirtualList virtualList)
{
if (!this.IsConnected)
{
return(0);
}
DataGridVirtualizingQueryableCollectionViewGroup collectionViewGroup =
this.GetLinkedCollectionViewGroup(virtualList) as DataGridVirtualizingQueryableCollectionViewGroup;
Debug.Assert(collectionViewGroup != null);
return(collectionViewGroup.QueryItemCount());
}
internal virtual IQueryable CreateUnsortedFilteredQueryable()
{
int level = this.Level;
Debug.Assert((level > -1), "The DataGridVirtualizingGroupRoot should have overriden this method without calling base.");
// Sub group. Only group from parent, which will already be sorted.
DataGridVirtualizingQueryableCollectionViewGroup parentCollectionViewGroup = this.Parent as DataGridVirtualizingQueryableCollectionViewGroup;
IQueryable parentUnsortedQueryable = parentCollectionViewGroup.UnsortedFilteredQueryable;
Debug.Assert(parentUnsortedQueryable != null);
if (parentUnsortedQueryable == null)
{
return(null);
}
// Narrow the filter to this group's clauses.
return(this.FilterQueryable(parentUnsortedQueryable));
}