private void SetCurrent(VirtualListItem <T> newItem, int newPosition)
{
var isCurrentBeforeFirst = _isCurrentBeforeFirst;
var isCurrentAfterLast = _isCurrentAfterLast;
var currentItem = _currentItem;
var 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);
}
}
public VirtualListItem <T> this[int index]
{
get
{
try
{
if (_list != null && _list[index] == null)// && _list.Length <= index
{
_list[index] = new VirtualListItem <T>(this, index);
}
return(_list != null ? _list[index] : null);
}
catch (Exception)
{
throw;
}
}
set
{
throw new NotSupportedException();
}
}
private void PopulatePageData(int startIndex, IList <T> pageData, int overallCount)
{
var flagRefresh = false;
if (_list == null || _list.Length != overallCount || overallCount == 0)
{
_list = new VirtualListItem <T> [overallCount];
flagRefresh = true;
}
for (var i = 0; i < pageData.Count; i++)
{
var index = startIndex + i;
if (index >= _list.Count())
{
continue;
}
if (_list.Count() == index || _list[index] == null)
{
_list[index] = new VirtualListItem <T>(this, index, pageData[i]);
}
else
{
_list[index].Data = pageData[i];
}
}
if (flagRefresh)
{
if (_synchronizationContext == null || SynchronizationContext.Current != null)
{
FireCollectionReset(null);
}
else
{
_synchronizationContext.Post(FireCollectionReset, null);
}
}
}
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);
}
