Retrieving Min/Max X-axis values

[JAV]

Hi everyone,

We need to get the minimum and the maximum value from the x-axis in a plot. This axis is in date format. We use the MinVisibleSeriesValue function.

The code is programmed in the OnClick Event:

Code: Select all

Chart1.Axis.Bottom.MinVisibleSeriesValue  (TRUE,0)
Chart1.Axis.Bottom.MaxVisibleSeriesValue  (TRUE,0)

It works fine, but when we zoom in the plot the following error message occurs:

Error message

MinVisibleSeriesValues.jpg (31.54 KiB) Viewed 20659 times

Please note, that the expected minimum value is 10/11/2000

[Yeray]

Hi,

I'm trying to reproduce it here with the following code, but I don't get any error and I seem to always obtain the correct value:

Code: Select all

Private Sub Form_Load()
  TChart1.Aspect.View3D = False
  TChart1.Legend.Visible = False
  
  TChart1.AddSeries scFastLine
  TChart1.Series(0).XValues.DateTime = True
  TChart1.Series(0).FillSampleValues
End Sub

Private Sub TChart1_OnClick()
  Caption = "Min: " + FormatDateTime(TChart1.Axis.Bottom.MinVisibleSeriesValue(True, 0)) + ", Max: " + FormatDateTime(TChart1.Axis.Bottom.MaxVisibleSeriesValue(True, 0))
End Sub

Are you using the latest version available?
Could you please modify the code above or arrange a simple example project we can run as-is to reproduce the problem here?
Thanks in advance.

[JAV]

Hi Yerav,
Thank you very much for answering.
This feature was working perfect with scFasLline series. Two extra scPoint series were added and the bottom axis label style was changed to two:

Code: Select all

TChart1.Axis.Bottom.Labels.Style = 2

The current example has only one point in each scPoint serie. We noted that when this scPoint series are unchecked the error disapeared.
The images attached showed the state before and after the zoom in and how the returned values are correct with scPoint uncheked.

1. Before Zoom In the date values returned are correct

BeforeZoomIn.jpg (61.65 KiB) Viewed 20605 times

2. Zoom In. Returned values do not corresponding with X-axis visible scale. The minimum value returns the error message reported before.

ZoomIn.jpg (50.96 KiB) Viewed 20602 times

3. ScPoint series unchecked. Returned values Ok.

Uncheked_OK.jpg (54.87 KiB) Viewed 20619 times

We're using TeeChart8.ocx

Regards,

JAV

[Yeray]

Hi,

I'm still not able to reproduce any error message with TeeChart ActiveX 8 (nor with the latest v2012) and the following code.
Please, try to arrange a simple example project we can run as-is to reproduce the problem here.

Code: Select all

Private Sub Form_Load()
  TChart1.Aspect.View3D = False
  TChart1.Legend.CheckBoxes = True
  TChart1.Axis.Bottom.Labels.Angle = 90
  TChart1.Axis.Left.Logarithmic = True
  TChart1.Axis.Left.SetMinMax 1, 10000
  
  TChart1.Axis.Bottom.Labels.Style = 2
  
  Dim i, j As Integer
  Dim tmpDate As Date
  For i = 0 To 1
    tmpDate = CDate("31/08/1997")
    TChart1.AddSeries scFastLine
    With TChart1.Series(i)
      .XValues.DateTime = True
      .AddXY tmpDate, 1000, "", clTeeColor
      For j = 1 To 199
        .AddXY tmpDate + j * 7, .YValues.Value(.Count - 1) + Rnd * 100 - 50, "", clTeeColor
      Next j
    End With
  Next i
  
  TChart1.AddSeries scPoint
  TChart1.Series(TChart1.SeriesCount - 1).XValues.DateTime = True
  TChart1.Series(TChart1.SeriesCount - 1).AddXY TChart1.Series(0).XValues.Value(150), TChart1.Series(0).YValues.Maximum + 100, "", clTeeColor
  
  TChart1.AddSeries scPoint
  TChart1.Series(TChart1.SeriesCount - 1).XValues.DateTime = True
  TChart1.Series(TChart1.SeriesCount - 1).AddXY CDate("5/12/2003"), TChart1.Series(0).YValues.Maximum + 100, "", clTeeColor
  
End Sub

Private Sub TChart1_OnClick()
  Caption = "Min: " + FormatDateTime(TChart1.Axis.Bottom.MinVisibleSeriesValue(True, 0)) + ", Max: " + FormatDateTime(TChart1.Axis.Bottom.MaxVisibleSeriesValue(True, 0))
End Sub

[JAV]

Hello Yeray,
Please find attached the data that is producing the error,

Regards,

JAV

[Yeray]

Hi,

I'm still not able to reproduce any error message here.
I've transformed your xls to csv so the data it contains can be imported with the following code:

Code: Select all

Private Sub Form_Load()    
  TChart1.Aspect.View3D = False  
  TChart1.Axis.Bottom.Labels.Style = 2 'talValue
  TChart1.Axis.Left.Logarithmic = True
  
  TChart1.AddSeries scFastLine
  TChart1.AddSeries scFastLine
  TChart1.AddSeries scPoint
  TChart1.AddSeries scPoint
  TChart1.Series(0).XValues.DateTime = True
  TChart1.Series(1).XValues.DateTime = True
  TChart1.Series(2).XValues.DateTime = True
  TChart1.Series(3).XValues.DateTime = True
  
  With SeriesTextSource1
    .FileName = "C:\tmp\Data.csv"
    .HeaderLines = 1
    .FieldSeparator = ";"
    
    .Series = TChart1.Series(0)
    .AddField "X", 1
    .AddField "Y", 2
    .Active = True

    .Series = TChart1.Series(1)
    .AddField "X", 3
    .AddField "Y", 4
    .Active = True

' This works with v2012, but with v8
'    .Series = TChart1.Series(2)
'    .AddField "X", 5
'    .AddField "Y", 6
'    .Active = True
'
'    .Series = TChart1.Series(3)
'    .AddField "X", 7
'    .AddField "Y", 8
'    .Active = True
  End With
  
' I add the values manually in v8:
  TChart1.Series(2).AddXY CDate("10/11/2003"), 0, "", clTeeColor
  TChart1.Series(3).AddXY CDate("01/02/1999"), 231.48, "", clTeeColor
End Sub

Private Sub TChart1_OnClick()
  Caption = "Min: " + FormatDateTime(TChart1.Axis.Bottom.MinVisibleSeriesValue(True, 0)) + ", Max: " + FormatDateTime(TChart1.Axis.Bottom.MaxVisibleSeriesValue(True, 0))
End Sub

When I click I don't get any error message. Maybe what you mean is that you'd expect different values to be returned?

[JAV]

Hi Yeray,
Please note that the problem occurs while zooming on the plot. At first view it brings the correct date range, but when zooming in, it retrieves a different range from what is displayed on the chart as is shown in the previous images.
Zooming in several times produces none returned value for the minimum limit. When the scSeries are disable, the limits are returned correctly.

Regards,

JAV

[Yeray]

Hi JAV,

I'm a bit confused. I'm not sure if we are talking about an error message or about a wrong value returned when MinVisibleSeriesValue is called.
At the first post you talked about an error message, showing a screenshot of it.

It works fine, but when we zoom in the plot the following error message occurs

You still talk about an error some post later:

Please find attached the data that is producing the error

But I seem to understand now it's a wrong returned value:

Please note that the problem occurs while zooming on the plot. At first view it brings the correct date range, but when zooming in, it retrieves a different range from what is displayed on the chart as is shown in the previous images.
Zooming in several times produces none returned value for the minimum limit. When the scSeries are disable, the limits are returned correctly.

[JAV]

Hi Yeray,

It's indeed both. The error message appears when you zoom in several times and refers to the minimum value, and, the maximum does not return the correct value when zooming in. However, when you uncheck scPoint, the returned values ​​are correct and no error message when zooming.

[Yeray]

Hi,

It's indeed both

Ok, thanks.

The error message appears when you zoom in several times and refers to the minimum value

I'm not able to reproduce this. Can you reproduce it with the code above?

the maximum does not return the correct value when zooming in. However, when you uncheck scPoint, the returned values ​​are correct and no error message when zooming.

I found this is nothing related to the logarithmic axis, neither with the datetimes. There seems to be 2 different problems here:
1. MinVisibleSeriesValue function is still considering the points in a series with FirstValueIndex=-1 and LastValueIndex=-1. Find below a manual implementation in VB6 of the same function, correcting this:

Code: Select all

Private Sub Form_Load() 
  TChart1.Aspect.View3D = False
 
  TChart1.AddSeries scFastLine
  TChart1.AddSeries scPoint
  TChart1.Series(0).FillSampleValues 10
  TChart1.Series(1).AddXY TChart1.Series(0).XValues.Value(5), TChart1.Series(0).YValues.Value(5), "", clTeeColor
End Sub

Private Sub TChart1_OnAfterDraw()
  Caption = "Min: " + Format$(MinVisibleSeriesValue(TChart1, TChart1.Axis.Bottom, True, 0)) + ", Max: " + Format$(MaxVisibleSeriesValue(TChart1, TChart1.Axis.Bottom, True, 0))
End Sub

Private Function MinVisibleSeriesValue(ByVal Chart As TChart, ByVal Axis As IAxis, ByVal AllSeries As Boolean, ByVal SeriesIndex As Integer) As Double
  MinVisibleSeriesValue = MaxMinVisibleValue(Chart, Axis, False, AllSeries, SeriesIndex)
End Function

Private Function MaxVisibleSeriesValue(ByVal Chart As TChart, ByVal Axis As IAxis, ByVal AllSeries As Boolean, ByVal SeriesIndex As Integer) As Double
  MaxVisibleSeriesValue = MaxMinVisibleValue(Chart, Axis, True, AllSeries, SeriesIndex)
End Function

Private Function MaxMinVisibleValue(ByVal Chart As TChart, ByVal Axis As IAxis, ByVal IsMax As Boolean, ByVal AllSeries As Boolean, ByVal SeriesIndex As Integer) As Double
  Dim i, j, firstSeries, startSeries, endSeries, a, b As Integer
  Dim tmpResult, tmpVal As Double
  Dim firstTime As Boolean
  
  firstSeries = -1
  firstTime = True
  tmpResult = 0
  
  With Chart
    If AllSeries Then
      For i = 0 To .SeriesCount - 1
        If (.Series(i).Active) Then
          firstSeries = i
          Exit For
        End If
      Next i
    Else
      firstSeries = SeriesIndex
    End If

    If (firstSeries >= 0) And (firstSeries < .SeriesCount) Then
      If AllSeries = True Then
        startSeries = 0
        endSeries = .SeriesCount - 1
      Else
        startSeries = SeriesIndex
        endSeries = SeriesIndex
      End If
      For i = startSeries To endSeries
        If ((SeriesAssociatedToAxis(.Series(i), Axis)) And (.Series(i).Active)) Then
          If (.Series(i).FirstValueIndex <> -1) And ((.Series(i).LastValueIndex <> -1)) Then
            For j = .Series(i).FirstValueIndex To .Series(i).LastValueIndex
              tmpVal = .Series(i).XValues.Value(j)

              If firstTime Then
                tmpResult = tmpVal
                firstTime = False
              Else
                If (IsMax) Then
                  If (tmpVal > tmpResult) Then
                    tmpResult = tmpVal
                  End If
                Else
                  If (tmpVal < tmpResult) Then
                    tmpResult = tmpVal
                  End If
                End If
              End If
            Next j
          End If
        End If
      Next i
    End If
  End With
  
  MaxMinVisibleValue = tmpResult
End Function

Private Function SeriesAssociatedToAxis(ByVal Series As ISeries, ByVal Axis As IAxis) As Boolean
  SeriesAssociatedToAxis = Series.UseAxis And (( _
                           ((Series.HorizontalAxis = aBothHorizAxis) Or (Series.HorizontalAxis = aBottomAxis))))
End Function

2. When you zoom or scroll the chart so the series with a unique point disappears on the right side, this series still has FirstValueIndex=0 and LastValueIndex=0, when both should be -1. I've added it to the defect list to be fixed in future releases (VCL: TV52016374).
In the meanwhile, you could calculate the FirstValueIndex and LastValueIndex manually, instead of using the provided properties, and use them in the MaxMinVisibleValue function above.

[JAV]

ok, thank you very much, please let us know when this bug is corrected.

regards,

JAV