Chart Control Y axis auto-scale on scrolling

Question

I've been searching the net for some time now yet still haven't found any good solution to my problem. I want to make MS Chart to automatically rescale Y axis on scrolling to make sure that all data points are visible. The twist here is that I need to have the ability to exclude certain series from being used for auto scale. So far I only found solutions that offer to iterate through the entire point collection on AxisViewChanged event, which doesn't work well when you have large collections of points and a few series to iterate through. I was wondering if there was any way to narrow the search by obtaining data points that are between currently visible min and max X values. Any help would be appreciated.

Edit Heres the image. As you can see the candlesticks in the middle aren't entirely visible.

Answer 1

you can try this code

        DateTime date = DateTime.Now;
        chart1.ChartAreas[0].AxisX.Minimum = 0;
        chart1.ChartAreas[0].AxisX.Maximum = 20;
        Random r = new Random((int)date.Ticks);

        chart1.Series[0].ChartType = SeriesChartType.Candlestick;
        chart1.Series[0].Color = Color.Green;
        chart1.Series[0].XValueType = ChartValueType.Time;
        chart1.Series[0].IsXValueIndexed = true;
        chart1.Series[0].YValuesPerPoint = 4;
        chart1.Series[0].CustomProperties = "MaxPixelPointWidth=10";
        for (int i = 0; i < 100; i++ )
        {
            DataPoint point = new DataPoint(date.AddHours(i).ToOADate(), new double[] { r.Next(10, 20), r.Next(30, 40), r.Next(20, 30), r.Next(20, 30) });
            chart1.Series[0].Points.Add(point);
        }

        int min = (int)chart1.ChartAreas[0].AxisX.Minimum;
        int max = (int)chart1.ChartAreas[0].AxisX.Maximum;

        if (max > chart1.Series[0].Points.Count)
            max = chart1.Series[0].Points.Count;

        var points = chart1.Series[0].Points.Skip(min).Take(max - min);

        var minValue = points.Min(x => x.YValues[0]);
        var maxValue = points.Max(x => x.YValues[1]);

        chart1.ChartAreas[0].AxisY.Minimum = minValue;
        chart1.ChartAreas[0].AxisY.Maximum = maxValue;

Answer 2

Use a query to find out which series you want to use for finding ymin and ymax in the code.

private void chart1_AxisViewChanged(object sender, ViewEventArgs e)
    {
        if (e.Axis.AxisName == AxisName.X)
        {
            int start = (int)e.Axis.ScaleView.ViewMinimum;
            int end = (int)e.Axis.ScaleView.ViewMaximum;

            // Series ss = chart1.Series.FindByName("SeriesName");
            // use ss instead of chart1.Series[0]

            double[] temp = chart1.Series[0].Points.Where((x, i) => i >= start && i <= end).Select(x => x.YValues[0]).ToArray();
            double ymin = temp.Min();
            double ymax = temp.Max();

            chart1.ChartAreas[0].AxisY.ScaleView.Position = ymin;
            chart1.ChartAreas[0].AxisY.ScaleView.Size = ymax - ymin;
        }
    }

Answer 3

This is a minor improvement on the excellent submission from Shivaram K R, to prevent open, close and low dropping off the bottom for the lowest points on financial charts with four Y values: high, low, open close.

// The following line goes in your form constructor
this.chart1.AxisViewChanged += new EventHandler<ViewEventArgs> (this.chart1_AxisViewChanged);


private void chart1_AxisViewChanged(object sender, ViewEventArgs e)
{ 
    if (e.Axis.AxisName == AxisName.X) 
    { 
        int start = (int)e.Axis.ScaleView.ViewMinimum; 
        int end = (int)e.Axis.ScaleView.ViewMaximum; 
        // Use two separate arrays, one for highs (same as temp was in Shavram's original)
        // and a new one for lows which is used to set the Y axis min.
        double[] tempHighs = chart1.Series[0].Points.Where((x, i) => i >= start && i <= end).Select(x => x.YValues[0]).ToArray();
        double[] tempLows = chart1.Series[0].Points.Where((x, i) => i >= start && i <= end).Select(x => x.YValues[1]).ToArray();
        double ymin = tempLows.Min();
        double ymax = tempHighs.Max();

        chart1.ChartAreas[0].AxisY.ScaleView.Position = ymin; 
        chart1.ChartAreas[0].AxisY.ScaleView.Size = ymax - ymin; 
    } 
}