Question

I m using the Microsoft Chart Controls for Microsoft .NET Framework 3.5 and am having a spot of trouble getting Data Markers to show on the image.

I m generating the chart at run-time, so can t just use the designer.

Sub New()
    MainChart = New Chart
    MainChart.Size = New Drawing.Size(500, 200)

    MainArea = New ChartArea()
    With MainArea
        .Name = "Default"
        .AxisX.LabelStyle.Format = "MMM"
        .AxisX.MajorGrid.Enabled = False
        .AxisX.IsLabelAutoFit = False

        .AxisY.MajorGrid.LineColor = Drawing.Color.Gainsboro
        .AxisY.IsLabelAutoFit = True
        .AxisY.Minimum = 0
        .AxisY.Maximum = 50
    End With
    MainChart.ChartAreas.Add(MainArea)


    MainSeries = New Series()
    With MainSeries
        .ChartArea = "Default"
        .Name = "MainSeries"
        .ChartType = SeriesChartType.Line   # .FastLine would hide markers...
        .IsXValueIndexed = True
        .XValueType = ChartValueType.Date
        .MarkerSize = 9
        .MarkerStyle = MarkerStyle.Diamond
        .ToolTip = "#VALX: #VAL"
    End With
    MainChart.Series.Add(MainSeries)

End Sub

I then add a bunch of data points using

Public Sub AddDataPoint(ByVal X As Date, ByVal Y As Double)
    MainSeries.Points.AddXY(X, Y)
End Sub

After that, I can save the chart as an image

Public Sub SaveImage(ByVal Filename As String)
   MainChart.SaveImage(Filename, ChartImageFormat.Png)
End Sub

Which all works lovely, and I get pretty charts. The only problem is that there are no markers on the datapoints.

Can anyone shed any light on what I m doing wrong?

Answer 1

I m an idiot.

I put in a testing override up there that I forgot about, to set the style to FastLine - which of course doesn t create markers etc.

I changed

.ChartType = SeriesChartType.FastLine

to

.ChartType = SeriesChartType.Line

And naturally it just works now :)

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