Question

How can I programmatically highlight a DataGrid cell in Silverlight?

Answer 1

You’ll need to do the following:

1. Add a property (let’s name it IsSelectedInChart) to your data item class. This property must be public and must raise the INotifyPropertyChanged.PropertyChanged event whenever its value changes.
2. In your lineseries_SelectionChanged you should find the data item that corresponds to the selected point and set IsSelectedInChart to true for it and to false for others.
3. Make all instances of DataGridRow that exist in the DataGrid have a Binding set to their Background property with Path=IsSelectedInChart and a custom `IValueConverter’.

The converter should look like this:

public class ValueConverter : IValueConverter
{
  public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
  {
    // TODO: be more careful with nulls and non-expected values
    bool isSelected = (bool)value;
    return isSelected ? new SolidColorBrush(Colors.Red) : DependencyProperty.UnsetValue;
  }
}

The last step is the trickiest. It may be implemented by overriding the DataGridRow Style. One approach is shown in https://stackoverflow.com/a/4268159/795861, another one in https://stackoverflow.com/a/3542179/795861. Check those out.

All these steps are required since you’re likely to have a lot of rows in the DataGrid. It uses UI virtualization which makes it impossible to simple set the Background property on the required DataGridRow because a single row object is used to present multiple data items. Thus, the only way to make it work with scrolling is binding the background to the data items.

UPDATE

To highlight cells in a column that is known at design time, set DataGridColumn.CellStyle property to that column definition instead of setting the row style:

<sdk:DataGrid>
  <sdk:DataGrid.Columns>
    <sdk:DataGridTextColumn x:Name="theColumnToHighlight">
      <sdk:DataGridTextColumn.CellStyle>
        <Style TargetType="{x:Type sdk:DataGridCell}">
          <Setter Property="local:SetterValueBindingHelper.PropertyBinding">
            <Setter.Value>
              <local:SetterValueBindingHelper
                  Type="System.Windows.Controls.Control, System.Windows, Version=2.0.5.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e"
                  Property="Background"
                  Binding="{Binding IsSelectedInChart, Converter={StaticResource highlighterConverter}}"/>
            </Setter.Value>
          </Setter>
        </Style>
      </sdk:DataGridTextColumn.CellStyle>
    </sdk:DataGridTextColumn>
  </sdk:DataGrid.Columns>
</sdk:DataGrid>

Should work, although I haven’t tried. The xaml does the same as I’ve suggested for highlighting entire rows, but applies it to cells in a specific column.