Question

I’m using MSChart and I want to enable zoom on the X Axis and once this is zoomed I want the Y Axis to auto zoom into a range appropriate for the data viewable.

Any assistance with the problem would be greatly appreciated!

Thanks

Answer 1

The kind of zooming that you want to do cannot be automatically accomplished by MSChart. Once you have retrieved the ‘Zoom-In’ X-value range from the user, you need to write a little more code to reset the Y-axis scaling appropriately.

This works most easily if you are using a Line style of data series and your source data for that series is stored as a SortedList.

Dim firstXindex as Int32 = myDataSeries.IndexOfKey(firstXzoomValue)
Dim lastXindex as Int32 = myDataSeries.IndexOfKey(lastXzoomValue)    

Dim minY as Double = 1.7E+308
Dim maxY as Double = -1.7E+308  


For i = firstXindex To lastXindex
    If myDataSeries.GetByIndex(i) > maxY Then
        maxY = myDataSeries.GetByIndex(i)
    End If
    If myDataSeries.GetByIndex(i) < minY Then
        minY = myDataSeries.GetByIndex(i)
    End If
Next

Once you have used something like the code above to get your minY and maxY, you can then use those values to reset the min and max Y-axis values on the ChartArea:

With myChartArea
  .AxisY.Maximum = maxY
  .AxisY.Minimum = minY
End With