How to display tooltips with various data in MS charts

问题

I am developing a candle chart in C #.

I've been working on creating candle charts using data from the current datagridview.

Additionally, when I place the cursor over the candle point of the chart, I want to show the information (open, close, high, low) of the datagridview. (See image)

Currently developed source.

    DataTable table_ChartData = new DataTable();
    table_ChartData.Columns.Add("Id");
    table_ChartData.Columns.Add("Open");
    table_ChartData.Columns.Add("Close");
    table_ChartData.Columns.Add("High");
    table_ChartData.Columns.Add("Low");
    table_ChartData.Columns.Add("Day");
    dataGridView1.DataSource = table_ChartData;  

    chart1.ChartAreas["ChartArea1"].AxisX.MajorGrid.LineWidth = 1;
    chart1.ChartAreas["ChartArea1"].AxisY.MajorGrid.LineWidth = 1;
    chart1.ChartAreas["ChartArea1"].AxisY.Maximum = max;
    chart1.ChartAreas["ChartArea1"].AxisY.Minimum = min;

    chart1.Series["Daily"].XValueMember = "Day";
    chart1.Series["Daily"].YValueMembers = "High,Low,Open,Close";
    chart1.Series["Daily"].XValueType = System.Windows.Forms.DataVisualization.Charting.ChartValueType.Date;

    chart1.Series["Daily"].CustomProperties = "PriceDownColor=Blue,PriceUpColor=Red";
    chart1.Series["Daily"]["OpenCloseStyle"] = "Triangle";
    chart1.Series["Daily"]["ShowOpenClose"] = "Both";

    chart1.DataSource = table_ChartData;
    chart1.DataBind();

    private void chart1_MouseMove(object sender, MouseEventArgs e)
    {

        Point mousePoint = new Point(e.X, e.Y);
        chart1.ChartAreas[0].CursorX.SetCursorPixelPosition(mousePoint, true);
        chart1.ChartAreas[0].CursorY.SetCursorPixelPosition(mousePoint, true);`

        var pos = e.Location;
        if (prevPosition.HasValue && pos == prevPosition.Value)
            return;
        tooltip.RemoveAll();
        prevPosition = pos;
        var results = chart1.HitTest(pos.X, pos.Y, false, ChartElementType.DataPoint); // set ChartElementType.PlottingArea for full area, not only DataPoints
        foreach (var result in results)
        {
            if (result.ChartElementType == ChartElementType.DataPoint) // set ChartElementType.PlottingArea for full area, not only DataPoints
            {
                var yVal = result.ChartArea.AxisY.PixelPositionToValue(pos.Y);
                tooltip.Show(((int)yVal).ToString(), chart1, pos.X, pos.Y - 15);
            }
        }

    }

Thank you for your help. Thank you :)

回答1:

You are creating ToolTips in the MouseMove; this is one way but the easiest approach is to let the Chart do the work by setting the DataPoint.Tooltip property right when you create the DataPoints..:

DataPoint dp = new DataPoint (..);
dp.ToolTip = "x=" + dp.XValue + "\n high=" + dp.YValues[0]+ "\n low=" + dp.YValues[1] + ..;
yourSeries.Points.Add(dp);

---

.. or, if the Points are DataBound either add ToolTips right after you bind or, maybe include them in the binding itself.

Note that only some of the various data binding methods will let you bind 'extended chart properties' like tooltips. Points.DataBind is mentioned explicitly. This means that you need a prepared field for the tooltips in your datasource as I know of no way to write a concatenating expression in the otherField string..

If you have your data in a DataTable with the fields below you can use syntax like this for the binding:

var enumerableTable = (dt as System.ComponentModel.IListSource).GetList();
yourSeries.Points.DataBind(enumerableTable, "x-col", 
                          "highField, lowField..", "Tooltip=tooltipField");

---

If you want to do it in the MouseMove you can easily get a reference to the DataPoint you are over, if any, and work with all its values like above..:

DataPoint dp = null;
if (results.PointIndex >= 0 && results.ChartElementType == ChartElementType.DataPoint)
{
    dp = results.Series.Points[hitt.PointIndex];
    string tText = "x=" + dp.XValue + "\n high=" + 
                   dp.YValues[0]+ "\n low=" + dp.YValues[1] + ..;
..
}

Note that the HitTest result is one object with several properties. No need to loop over it!

来源：https://stackoverflow.com/questions/46212740/how-to-display-tooltips-with-various-data-in-ms-charts