Use ISO 8601 for week numbers in DateEdit

Hi Andrey,

thank you for your answer. I understand that you still have to support also "old" .NET Framework. Your solution with overriding theme resources seems to work fine. I just had to do some small tweaks.

For anybody interested in a solution:
The implementation in the sample is really just a sample and won't work properly if month doesn't spread across 6 weeks. To get proper date range for computing week numbers I used items (days) already existing in DateNavigatorCalendarContentControl. I hope that's ok and it won't have any side effects that I don't see right now ;-)

Here is my modified converter (could be further simplified to IValueConverter):

Visual Basic
Imports System.Globalization
Imports System.Windows.Markup
Imports DevExpress.Xpf.Editors.DateNavigator.Controls

Namespace UI.Converters

  Public Class DateEditWeekNumberConverter
    Inherits MarkupExtension
    Implements IMultiValueConverter

    Public Overrides Function ProvideValue(serviceProvider As IServiceProvider) As Object
      Return Me
    End Function

    Public Function Convert(values As Object(), targetType As Type, parameter As Object, culture As CultureInfo) As Object Implements IMultiValueConverter.Convert
      If values Is Nothing OrElse Not values.Length = 3 OrElse TypeOf values(2) IsNot DateNavigatorCalendarContentControl Then
        Return Nothing
      End If

      Dim ctrl = DirectCast(values(2), DateNavigatorCalendarContentControl)

      Dim items = ctrl.ItemsSource?.OfType(Of DateNavigatorCalendarCellViewModel).ToList()

      If items Is Nothing OrElse Not items.Any() Then
        Return Nothing
      End If

      Return items.GroupBy(Function(x) ISOWeek.GetWeekOfYear(x.DateTime)). ' NOTE: do not use Distinct; GroupBy preserves source order, Distinct might not
                   Select(Function(x) x.Key).
                   ToList()
    End Function

    Public Function ConvertBack(value As Object, targetTypes As Type(), parameter As Object, culture As CultureInfo) As Object() Implements IMultiValueConverter.ConvertBack
      Throw New NotImplementedException()
    End Function

  End Class
End Namespace

XAML
<ItemsControl x:Name="PART_WeekNumbersItemsControl" Visibility="{Binding Path=(dxedn:DateNavigator.Navigator).ShowWeekNumbers, RelativeSource={RelativeSource Self}, Converter={StaticResource BoolToVisibilityConverter}}" Grid.Row="2" Grid.Column="0">
    <ItemsControl.ItemsSource>
        <MultiBinding Converter="{StaticResource DateEditWeekNumberConverter}">
            <Binding Path="DateTime" RelativeSource="{RelativeSource AncestorType=dxednc:DateNavigatorCalendarContentControl}"/>
            <Binding Path="WeekNumbers" RelativeSource="{RelativeSource AncestorType=dxednc:DateNavigatorCalendarContentControl}"/>
            <Binding Path="" RelativeSource="{RelativeSource AncestorType=dxednc:DateNavigatorCalendarContentControl}"/>
        </MultiBinding>
    </ItemsControl.ItemsSource>
    ...
</ItemsControl>

Kind regards
Peter

Hello Peter,

Thank you for your understanding - I really appreciate it. I would like to emphasize that we keep all such inquiries in mind and think of ways to enhance DateEdit's behavior in this regard. Perhaps we will be able to at least rework the inner classes so that the related methods are implemented virtually. This way, it will be possible to accomplish the task without overriding theme resources.

I also want to thank you for sharing the modifications you used in your own implementation. They indeed will be helpful for other customers.

Feel free to contact us if you have other questions.

Regards,
Andrey