C＃如何使用OADate转换数据库中的日期？

Question

我有一个日期和股票价格的数据库表。我根据文章将它绑定到WinForm Chart控件。 https://msdn.microsoft.com/en-us/library/dd489231(v=vs.110).aspx

我想在本文中标记最高数据点。 https://msdn.microsoft.com/en-us/library/dd456612(v=vs.110).aspx

// Get relative coordinates of the data point
System.Drawing.PointF pos = System.Drawing.PointF.Empty;
pos.X = (float)cg.GetPositionFromAxis("ChartArea1", AxisName.X, i);
pos.Y = (float)cg.GetPositionFromAxis("ChartArea1", AxisName.Y, max);

// Convert relative coordinates to absolute coordinates.
os = cg.GetAbsolutePoint(pos);

由于X轴是日期时间值，我得到了pos.X = -99845。我想我应该使用OADate作为文章。 https://msdn.microsoft.com/en-us/library/dd456614(v=vs.110).aspx但我还没有找到绑定源的方法。

Answer 1

我发现我应该在该教程示例中使用点的X值而不是其索引。

private void chart_PostPaint(object sender, ChartPaintEventArgs e)
{
    if (e.ChartElement is Series && ((Series)e.ChartElement).Name == "Series3")
    {
        Series s = e.Chart.Series[0];
        ChartGraphics cg = e.ChartGraphics;
        double max = s.Points.FindMaxByValue().YValues[0];

        for (int i = 0; i < s.Points.Count; i++)
        {
            if (s.Points[i].YValues[0] == max)
            {
                PointF pos = PointF.Empty;
                pos.X = (float)cg.GetPositionFromAxis("ChartArea1", AxisName.X, s.Points[i].XValue);
                pos.Y = (float)cg.GetPositionFromAxis("ChartArea1", AxisName.Y, max);

                pos = cg.GetAbsolutePoint(pos);

                for (int r = 10; r < 40; r+=10)
                {
                    cg.Graphics.DrawEllipse(
                        Pens.Red,
                        pos.X - r / 2,
                        pos.Y - r / 2,
                        r, r);
                }
            }
        }
    }
}