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Set LightweightCellEditor Background property dynamically using converter

created 5 days ago (modified 5 days ago)

I'm probably over-complicating this but I am trying to bind a decimal value using a custom converter to set the Background property of my LightweightCellEditor as follows:

XAML
<UserControl.Resources>
  <converters:SentimentColorConverter x:Key="SentimentColorConverter"/>
</UserControl.Resources>

...

<dxg:GridColumn.CellStyle>
  <Style TargetType="{x:Type dxg:LightweightCellEditor}">
    <Setter Property="Background">
      <Setter.Value>
        <SolidColorBrush Color="{Binding WeightedAverageSentimentNumeric, Converter={StaticResource SentimentColorConverter}}" />
      </Setter.Value>
    </Setter>
  </Style>
</dxg:GridColumn.CellStyle>

And my converter class:

C#
public class SentimentColorConverter : IValueConverter
{
  public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
  {
    if (value is decimal sentimentScore)
    {
        return sentimentScore switch
        {
          > 0.5m => Colors.LightGreen,
          > 0m => Colors.PaleGreen,
          < -0.5m => Colors.LightCoral,
          < 0m => Colors.LightPink,
          _ => Colors.LightYellow
        };
    }
    return Colors.LightGray; // Default for null or invalid values
  }

  public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
  {
      throw new NotImplementedException();
  }
}

The background never gets set however. If I set a breakpoint in the Convert() method it never gets triggered. If I set the Background property to a hard-coded Color value, it works as expected so presumably I'm doing something wrong with the binding.

Thanks for your help.

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Answers approved by DevExpress Support

created 5 days ago

Hello,

Thank you for the code snippets.

At first glance, it may be more suitable to bind the Background property directly to your cell value:

XAML
<Style TargetType="{x:Type dxg:LightweightCellEditor}">
  <Setter Property="Background" Value="{Binding WeightedAverageSentimentNumeric, Converter={StaticResource SentimentColorConverter}}" />
</Style>

Then, in your converter, return a Brush object:

C#
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
  if (value is decimal sentimentScore)
  {
    return sentimentScore switch
    {
      > 0.5m => Brushes.LightGreen,
      > 0m => Brushes.PaleGreen,
      < -0.5m => Brushes.LightCoral,
      < 0m => Brushes.LightPink,
      _ => Brushes.LightYellow
    };
  }
  return Brushes.LightGray; // Default for null or invalid values
}

Alternatively, you can use our GridControl Conditional Formatting, which allows you to change cell appearance based on different conditions. We demonstrated their use in the following help topic: How to Conditionally Set Background and Foreground for Grid Rows and Cells.

Please let me know if this helps.

Regards,
Marc

    Show previous comments (3)
    Marc T (DevExpress Support) 3 days ago

      Hello,

      Thank you for the update.

      I reexamined your code snippet, and it appears I missed the fact that the binding for Background directly refers to a property in your data item, but such bindings need to follow recommendations in the CellStyle | Data Binding help topic. Please accept my apologies for this oversight.

      I recommend you change the binding paths in your CellStyle definition to the following:

      XAML
      <Style TargetType="{x:Type dxg:LightweightCellEditor}">
    <Setter Property="Background">
        <Setter.Value>
            <SolidColorBrush Color="{Binding Value, Converter={StaticResource SentimentColorConverter}}" />
        </Setter.Value>
    </Setter>
</Style>
<!-- OR -->
<Style TargetType="{x:Type dxg:LightweightCellEditor}">
    <Setter Property="Background">
        <Setter.Value>
            <SolidColorBrush Color="{Binding RowData.Row.WeightedAverageSentimentNumeric, Converter={StaticResource SentimentColorConverter}}" />
        </Setter.Value>
    </Setter>
</Style>

      The first definition binds directly to the cell value. In this case, it makes sense to use this definition directly in the WeightedAverageSentimentNumeric column. The second definition allows you to use other properties in your data item. You can still use this definition, and it should work identically to the first. In addition, you will be able to use it in other columns as well.

      To learn more about building binding paths for cell elements, see the following example: Build Binding Paths in WPF Data Grid Cells.

      I attached a sample project to demonstrate the solution. Please try similar changes in your application and let me know if this works. Otherwise, please modify my sample project to illustrate the issue. This way, we will be in a better position to find a more suitable solution.

      Regards,
      Marc

      I I
      illya 3 days ago

        Fantastic, both suggestions appear to work, only change I had to make was to use System.Windows.Media.Colors instead of Brushes in my converter class.

        Marc T (DevExpress Support) 3 days ago

          I'm happy to hear that it helped. Thank you for keeping us informed.

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