private void initValues()
{
_maxValueItem = Items.OrderByDescending(x => x.Value).First();
var maxValueWidth = getTextWidth(_maxValueItem.Value.ToString(CultureInfo.InvariantCulture));
_leftMargin = maxValueWidth + Margin;
_chartWidth = _leftMargin + (Items.Count() * (SpaceBetweenBars + BarWidth)) + (2 * Margin);
}