图表控制 Y 轴滚动时自动缩放

Question

我已经在网上搜索了一段时间，但仍然没有找到任何好的解决方案来解决我的问题。我想让 MS Chart 在滚动时自动重新缩放 Y 轴，以确保所有数据点都可见。这里的问题是我需要能够排除某些系列用于自动缩放。到目前为止，我只找到了可以在 AxisViewChanged 事件上迭代整个点集合的解决方案，当您有大量点集合和几个要迭代的系列时，该解决方案效果不佳。我想知道是否有任何方法可以通过获取当前可见的最小和最大 X 值之间的数据点来缩小搜索范围。任何帮助将不胜感激。

编辑 这是图像。正如您所看到的，中间的烛台并不完全可见。

Answer 1

你可以尝试这个代码

        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

使用查询找出要使用哪个系列来查找代码中的 ymin 和 ymax。

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

这是对 Shivaram KR 提交的优秀提交的一个小改进，以防止金融图表上具有四个 Y 值的最低点的开盘价、收盘价和低点跌落底部：最高价、最低价、开盘收盘价。

// 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; 
    } 
} 

Answer 4

根据之前的答案，

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;

            List<double> allNumbers = new List<double>();

            foreach(Series item in chart1.Series)
                allNumbers.AddRange(item.Points.Where((x, i) => i >= start && i <= end).Select(x => x.YValues[0]).ToList());

            double ymin = allNumbers.Min();
            double ymax = allNumbers.Max();

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

图表区域中可能有更多系列。在这种情况下，您可以选择该区域中所有系列的最高价和最低价，而不仅仅是一个系列。

问候，

马泰斯

Answer 5

上面的回答对我来说非常有帮助。但是，我有一个包含多个图表区域的图表。我已经调整了代码以扩展到所有图表区域：

    foreach (ChartArea area in chart1.ChartAreas)
    {
      List<double> allNumbers = new List<double>();

      foreach (Series item in chart1.Series)
        if (item.ChartArea == area.Name)
          allNumbers.AddRange(item.Points.Where((x, i) => i >= start && i <= end).Select(x => x.YValues[0]).ToList());

      double ymin = allNumbers.Min();
      double ymax = allNumbers.Max();

      if (ymax > ymin)
      {
        double offset = 0.02 * (ymax - ymin);
        area.AxisY.Maximum = ymax + offset;
        area.AxisY.Minimum = ymin - offset;
      }
    }