Question

I’ve got a situation in which I need to show an integer value, bound to a property on my data context, after putting it through two separate conversions:

1. Reverse the value within a range (e.g. range is 1 to 100; value in datacontext is 90; user sees value of 10)
2. convert the number to a string

I realise I could do both steps by creating my own converter (that implements IValueConverter). However, I’ve already got a separate value converter that does just the first step, and the second step is covered by Int32Converter.

Is there a way I can chain these two existing classes in XAML without having to create a further class that aggregates them?

If I need to clarify any of this, please let me know. 🙂

Thanks.

Answer 1

I used this method by Gareth Evans in my Silverlight project.

Here’s my implementation of it:

public class ValueConverterGroup : List<IValueConverter>, IValueConverter
{
    #region IValueConverter Members

    public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        return this.Aggregate(value, (current, converter) => converter.Convert(current, targetType, parameter, culture));
    }

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

    #endregion
}

Which can then be used in XAML like this:

<c:ValueConverterGroup x:Key="InvertAndVisibilitate">
   <c:BooleanInverterConverter/>
   <c:BooleanToVisibilityConverter/>
</c:ValueConverterGroup>