MinorGrid Labels for DateTimeCategoryAxis

[Tom]

Hello, I have a chart with chart axis labels for each day with corresponding gridlines which are added manually to a DateTimeCategoryAxis via the GenerateVisibleLabels sub. Now, I would like to add additional labels for each hour from 9 am to 4 pm, but without gridlines. However, I cannot find a way to prevent gridlines being added to these hour labels.

Attached is an image showing what I mean, and a sample application. Run the sample and press the "Zoom 3 days" button. The sample works fine, expect I want to remove the vertical gridlines for the hour labels. How can this be achieved?

Thank you.

Attachment: sfChartNoGridlineLabels_f2cbed3.rar

[Muneesh Kumar G]

Hi Tom, 

 

Greetings, we have analyzed your requirement and we have achieved this by adding TextAnnotations for hour labels instead of adding VisibleLabels. Because we have drawn gridlines based on the VisibleLabels count. Please find the modified code snippet below.  

 

Code snippet 

Protected Overrides Sub GenerateVisibleLabels() 

 

        If IntervalType = DateTimeIntervalType.Days Then 

 

            Dim area = CType(Me.GetType().GetProperty("Area", BindingFlags.GetProperty Or BindingFlags.NonPublic Or BindingFlags.Instance).GetValue(Me), SfChart) 

            area.Annotations.Clear() 

.. 

 

                    Else   'ADD NEW HOUR LABEL 

                        If xDateTime >= nextHour Then 

 

                            If Not xDateTime.Hour = 16 Then 'do not add last hour of the day label to prevent intersection with the next date label 

                                Dim labelString As String = xDateTime.ToString("HH", Globalization.CultureInfo.CurrentCulture) 

                                Dim annotation As TextAnnotation = New TextAnnotation 

                                annotation.X1 = position 

                                annotation.Y1 = 100 

                                annotation.HorizontalAlignment = HorizontalAlignment.Center 

                                annotation.VerticalAlignment = VerticalAlignment.Center 

                                annotation.Foreground = New SolidColorBrush(Colors.White) 

                                annotation.Text = labelString 

                                area.Annotations.Add(annotation) 

 

                            End If 

 

                            nextHour = nextHour.AddHours(1) 

 

                        End If 

 

                    End If 

 

                    position += 1 

                Loop 

 

            End If 

        Else 

            MyBase.GenerateVisibleLabels() 

        End If 

 

 

    End Sub 

 

Here we have added the annotation at Y-Axis position of 100. You can modify this position based on you need.  

 

Please find the sample from the following location.  

 

Sample: http://www.syncfusion.com/downloads/support/forum/141524/ze/sfChartNoGridlineLabels-1117277824 

 

Screenshot: 

 

 

Thanks, 

Muneesh Kumar G. 

[Tom]

Thank you Muneesh, I've set the hour labels to the correct Y position with this code:

  Else   'ADD NEW HOUR LABEL

                        If xDateTime >= nextHour Then

                            If Not xDateTime.Hour = 16 Then 'do not add last hour of the day label to prevent intersection with the next date label

                                Dim labelString As String = xDateTime.ToString("HH", Globalization.CultureInfo.CurrentCulture)

                                Dim annotation As TextAnnotation = New TextAnnotation

                                annotation.CoordinateUnit = CoordinateUnit.Axis

                                annotation.XAxisName = MainWindow.XAxis.Name

                                annotation.YAxisName = MainWindow.YAxisPrice.Name

                                annotation.X1 = position

                                annotation.Y1 = MainWindow.chart.PointToValue(MainWindow.YAxisPrice, New Point(0, 14))

                                annotation.HorizontalAlignment = HorizontalAlignment.Center

                                annotation.VerticalAlignment = VerticalAlignment.Center

                                annotation.Foreground = New SolidColorBrush(Colors.White)

                                annotation.FontSize = 10

                                annotation.Text = labelString

                                area.Annotations.Add(annotation)

                            End If

                            nextHour = nextHour.AddHours(1)

                        End If

                    End If

Initially, it works fine. However, now a new issue has cropped up. To reproduce the issue, change to the above code, run the sample, press the 3 day zoom button. The hour labels are correctly aligned with the date labels. Now, click the maximize button to maximize the main window (assuming it started windowed). Now the hour labels appear below the date labels. After scrolling the chart, the hour labels are again correctly aligned.

I guess the PointToValue method doesn't calculate the updated YAxisPrice axis size, or the YAxisPrice size has not yet been updated with the new window size by the time the GenerateVisibleLabels sub is called. How can this issue be resolved? 

Thank you.

[Muneesh Kumar G]

Hi Tom, 

 

Thanks for your update, we have analyzed your query and we have resolved that by updating annotation’s Y1 position in SfChart’s LayoutUpdated event as per the below code snippet.  

 

Code Snippet 

 

        <chart:SfChart LayoutUpdated="Chart_LayoutUpdated" > 

        … 

        </chart:SfChart> 

 

 

 

    Private Sub Chart_LayoutUpdated(sender As Object, e As EventArgs) 

        Dim chart = CType(sender, SfChart) 

        Dispatcher.BeginInvoke(DispatcherPriority.Normal, New Action(AddressOf UpdateAnnotation)) 

    End Sub 

 

    Private Sub UpdateAnnotation() 

        If chart.Annotations IsNot Nothing Then 

            For Each item As Annotation In chart.Annotations 

                item.Y1 = chart.PointToValue(YAxisPrice, New Point(0, 14)) 

            Next 

        End If 

    End Sub 

 

 

We have modified our sample based on this, please find the sample from the following location.  

 

Sample: http://www.syncfusion.com/downloads/support/forum/141524/ze/sfChartNoGridlineLabels-1210644172.zip 

 

Hope it helps you.  

 

Regards, 

Muneesh Kumar G.  

 

[Tom]

Hi Muneesh, your sample freezes after clicking the 3 day zoom button. The Chart_LayoutUpdated sub gets called repeatedly.

[Muneesh Kumar G]

Hi Tom, 

 

Thanks for your update, we have already the reported scenario with our sample. It works fine with all zoom button. I have attached the reference video for that scenario in below location, please find it.  

 

Video: http://www.syncfusion.com/downloads/support/forum/141524/ze/Annotation-164198844 

 

If you still face the problem, please share your machine details, Visual Studio version and used Syncfusion version in your application with us. This would be helpful for us to give better solution in this.  

 

Thanks, 

Muneesh Kumar G. 

 

[Tom]

Hi Muneesh, thanks for checking this out. It is strange that it works on your machine but not mine. I'm using VS17 Community 15.9.4 (latest), with the latest 16.4460.0.42 sfchart version. 

However, if I cange 

Dispatcher.BeginInvoke(DispatcherPriority.Normal, New Action(AddressOf UpdateAnnotation))

to

Dispatcher.Invoke(DispatcherPriority.Normal, New Action(AddressOf UpdateAnnotation))

it works fine.

Also, if I change

Dispatcher.BeginInvoke(DispatcherPriority.Normal, New Action(AddressOf UpdateAnnotation))

to 

UpdateAnnotation()

it works fine.

I guess because BeginInvoke is asynchronous, there is some problem.

I found the best solution is to replace the Chart_LayoutUpdated sub with this:

Private Sub chart_SizeChanged(sender As Object, e As SizeChangedEventArgs) Handles chart.SizeChanged

        UpdateAnnotation()

End Sub

which seems to perform well, since it's only called once when the window size changes. So, for me the issue is solved, but it's unfortunate the BeginInvoke method doesn't work, because I guess it's potentially the best performing method. Anyway, thanks again.

[Muneesh Kumar G]

Hi Tom, 

 

Glad that the issue has been resolved and please get back to us if you need any other assistance.  

 

Regards, 

Muneesh Kumar G.