Forex_Strategy_Builder.Chart.ZoomOut C# (CSharp) Method

        void ZoomOut()
        {
            barPixels -= 4;
            if (barPixels < 4)
                barPixels = 2;

            int oldChartBars = chartBars;

            chartBars = chartWidth / barPixels;
            if (chartBars > Data.Bars - Data.FirstBar)
                chartBars = Data.Bars - Data.FirstBar;

            if (lastBar < Data.Bars - 1)
            {
                firstBar -= (chartBars - oldChartBars) / 2;
                if (firstBar < Data.FirstBar)
                    firstBar = Data.FirstBar;

                if (firstBar > Data.Bars - chartBars)
                    firstBar = Data.Bars - chartBars;
            }
            else
            {
                firstBar = Math.Max(Data.FirstBar, Data.Bars - chartBars);
            }

            lastBar = firstBar + chartBars - 1;

            scroll.Value = firstBar;
            scroll.LargeChange = chartBars;

            InvalidateAllPanels();

            return;
        }