private void SetCurrent(VirtualListItem <T> newItem, int newPosition)
{
bool isCurrentBeforeFirst = _isCurrentBeforeFirst;
bool isCurrentAfterLast = _isCurrentAfterLast;
VirtualListItem <T> currentItem = _currentItem;
int currentPosition = _currentPosition;
_isCurrentBeforeFirst = newPosition < 0;
_isCurrentAfterLast = newPosition >= Count;
_currentItem = newItem;
_currentPosition = newPosition;
if (currentItem != _currentItem)
{
OnCurrentChanged();
}
if (isCurrentBeforeFirst != _isCurrentBeforeFirst)
{
OnPropertyChanged(_isCurrentBeforeFirstChanged);
}
if (isCurrentAfterLast != _isCurrentAfterLast)
{
OnPropertyChanged(_isCurrentAfterLastChanged);
}
if (currentItem != _currentItem)
{
OnPropertyChanged(_currentItemChanged);
}
if (currentPosition != _currentPosition)
{
OnPropertyChanged(_currentPositionChanged);
}
}
private void PopulatePageData(int startIndex, IList <T> pageData, int overallCount)
{
bool flagRefresh = false;
if (_list == null || _list.Length != overallCount)
{
_list = new VirtualListItem <T> [overallCount];
flagRefresh = true;
}
for (int i = 0; i < pageData.Count; i++)
{
int index = startIndex + i;
if (_list[index] == null)
{
_list[index] = new VirtualListItem <T>(this, index, pageData[i]);
}
else
{
_list[index].Data = pageData[i];
}
}
if (flagRefresh)
{
if (this._synchronizationContext == null || SynchronizationContext.Current != null)
{
FireCollectionReset(null);
}
else
{
_synchronizationContext.Send(FireCollectionReset, null);
}
}
}
public VirtualListItem <T> this[int index]
{
get
{
if (_list[index] == null)
{
_list[index] = new VirtualListItem <T>(this, index);
}
return(_list[index]);
}
set
{
throw new NotSupportedException();
}
}
bool ICollection <VirtualListItem <T> > .Remove(VirtualListItem <T> item)
{
throw new NotSupportedException();
}
void ICollection <VirtualListItem <T> > .Add(VirtualListItem <T> item)
{
throw new NotSupportedException();
}
void IList <VirtualListItem <T> > .Insert(int index, VirtualListItem <T> item)
{
throw new NotSupportedException();
}
public int IndexOf(VirtualListItem <T> item)
{
return(item == null || item.List != this ? -1 : item.Index);
}
public bool Contains(VirtualListItem <T> item)
{
return(IndexOf(item) != -1);
}