public static IRowCol Advance(this IRowCol RowCol, int Length)
{
int col = RowCol.ColNum + Length;
int row = RowCol.RowNum;
// negative advance and column off the charts to the left.
while (col < RowCol.HorzBounds.a)
{
col += RowCol.Width();
row -= 1;
if (row < RowCol.VertBounds.a)
{
row = RowCol.VertBounds.b;
}
}
// positive advance and column out of bounds to the right.
while (col > RowCol.HorzBounds.b)
{
col -= RowCol.Width();
row += 1;
if (row > RowCol.VertBounds.b)
{
row = RowCol.VertBounds.a;
}
}
return(new ZeroRowCol(row, col));
}