public void PrevLine()
{
// New top line is one further up
int prevTopLine = _topLine;
_topLine = Math.Max(_topLine - 1, 0);
if (ScrollIntoView)
{
// Offset forwards so previous top line is starting position
_offset += _itemSize.Height;
// If offset is still positive then need to check the begin line
if (_offset > 0)
{
// Ensure the old top line can be displayed during scrolling
if ((_beginLine == -1) || (_beginLine < prevTopLine))
_beginLine = prevTopLine;
}
// Start the scrolling
_scrollTimer.Start();
}
}