Sometimes it is necessary that you have a converter (interface IValueConverter) with multiple parameters. To reach this goal, you can use a DependencyProperty. That’s normally a very easy step, but I spend some extraordinary time with my converter becuase in my case the second parameter should be bindable
– So what was the problem?
I have tried to derive the Converter from UserControl – great mistake: You have to use FrameworkElement instead!
Usage:
1: <Helpers:StatisticsConverter x:Key="StatisticsConverter" ViewModel="{Binding ElementName=LayoutRoot,Path=DataContext.Statistics}" />
2:
3: <TextBlock Margin="0,0,10,0"
4: FontSize="9"
5: x:Name="InfoSummeText" Text="{Binding Converter={StaticResource StatisticsConverter}, ConverterParameter=Summe}" >
6: </TextBlock>
Converter:
1: public class StatisticsConverter : FrameworkElement, IValueConverter
2: {
3:
4: #region IValueConverter Members
5:
6: public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
7: {
8: var statisticsViewModel = (StatisticsViewModel)ViewModel;
9: var statistics = statisticsViewModel.GetAnzeigeKategorieStatistics(value as AnzeigeKategorie);
10: switch (parameter.ToString())
11: {
12: case "Summe":
13: {
14: return String.Format("{0:N2}", statistics.Summe) + " EUR";
15: }
16: default:
17: {
18: throw new NotImplementedException(parameter as string);
19: }
20: }
21: }
22:
23: public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
24: {
25: return "";
26: }
27:
28: #endregion
29:
30: #region object ViewModel (DependencyProperty)
31:
32: public object ViewModel
33: {
34: get { return (object)GetValue(ViewModelProperty); }
35: set { SetValue(ViewModelProperty, value); }
36: }
37:
38: public static readonly DependencyProperty ViewModelProperty =
39: DependencyProperty.Register(
40: "ViewModel",
41: typeof(object),
42: typeof(StatisticsConverter),
43: new PropertyMetadata(null, null));
44:
45:
46: #endregion ViewModel (DependencyProperty)
47: }
