/// <summary>
/// This sets up the visible cells, adding and recycling as necessary
/// </summary>
private void _ResetVisibleCellViews()
{
int startIndex;
int endIndex;
// calculate the range of the visible cells
_CalculateCurrentActiveCellRange(out startIndex, out endIndex);
// go through each previous active cell and recycle it if it no longer falls in the range
var i = 0;
SmallList<int> remainingCellIndices = new SmallList<int>();
while (i < _activeCellViews.Count)
{
if (_activeCellViews[i].cellIndex < startIndex || _activeCellViews[i].cellIndex > endIndex)
{
_RecycleCell(_activeCellViews[i]);
}
else
{
// this cell index falls in the new range, so we add its
// index to the reusable list
remainingCellIndices.Add(_activeCellViews[i].cellIndex);
i++;
}
}
if (remainingCellIndices.Count == 0)
{
// there were no previous active cells remaining,
// this list is either brand new, or we jumped to
// an entirely different part of the list.
// just add all the new cell views
for (i = startIndex; i <= endIndex; i++)
{
_AddCellView(i, ListPositionEnum.Last);
}
}
else
{
// we are able to reuse some of the previous
// cell views
// first add the views that come before the
// previous list, going backward so that the
// new views get added to the front
for (i = endIndex; i >= startIndex; i--)
{
if (i < remainingCellIndices.First())
{
_AddCellView(i, ListPositionEnum.First);
}
}
// next add teh views that come after the
// previous list, going forward and adding
// at the end of the list
for (i = startIndex; i <= endIndex; i++)
{
if (i > remainingCellIndices.Last())
{
_AddCellView(i, ListPositionEnum.Last);
}
}
}
// update the start and end indices
_activeCellViewsStartIndex = startIndex;
_activeCellViewsEndIndex = endIndex;
// adjust the padding elements to offset the cell views correctly
_SetPadders();
}