WPF: ErrorMessage when trying to Bind a Line to two UIElements

Question

Im trying to bind a Line to two ScatterViewItems:

private void BindLineToScatterViewItems(Shape line, ScatterViewItem origin, ScatterViewItem destination)
        {
            // Bind line.(X1,Y1) to origin.ActualCenter
            BindingOperations.SetBinding(line, Line.X1Property, new Binding { Source = origin, Path = new PropertyPath("ActualCenter.X") });
            BindingOperations.SetBinding(line, Line.Y1Property, new Binding { Source = origin, Path = new PropertyPath("ActualCenter.Y") });

            // Bind line.(X2,Y2) to destination.ActualCenter
            BindingOperations.SetBinding(line, Line.X2Property, new Binding { Source = destination, Path = new PropertyPath("ActualCenter.X") });
            BindingOperations.SetBinding(line, Line.Y2Property, new Binding { Source = destination, Path = new PropertyPath("ActualCenter.Y") });
        }

But I always get the following error message:

System.Windows.Data Error: 5 : Value produced by BindingExpression is not valid for target property.; Value='NaN' BindingExpression:Path=ActualCenter.X; DataItem='ScatterViewItem' (Name=''); target element is 'Line' (Name=''); target property is 'X1' (type 'Double')

Nevertheless it is working, but how can I surpress this warning? And why is this warning displayed?

EDIT: According to the answer below, I use now following converter, but still get the errors:

public class NormalizationConverter : IValueConverter

    {
        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
           return (double) value == double.NaN ? Binding.DoNothing : (double) value;
        }

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

score 2 · Accepted Answer · answered Feb 16 '11 at 00:44

2

I don't have Surface but apparently ActualCenter.X and ActualCenter.Y start out as double.NaN before they are assigned their actual values. Since this doesn't last long, you could you any other double value instead. So to avoid the warning, you can use a converter that translates double.NaN to O:

public class NormalizationConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        var doubleValue = (double)value;
        return doubleValue == double.NaN ? 0 : doubleValue;
    }

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

answered Feb 16 '11 at 00:44

Rick Sladkey

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I'm partial to using Binding.DoNothing in such cases. – Goran Feb 16 '11 at 00:48
1

You can use `return doubleValue == double.NaN ? Binding.DoNothing : doubleValue;`. – Rick Sladkey Feb 16 '11 at 01:16
@Rick Sladkey I edited my question since i still get the errors – RoflcoptrException Feb 16 '11 at 14:10
Because I'm not running Surface I cannot test it. Try putting a breakpoint in the converter to make sure it is being called. – Rick Sladkey Feb 16 '11 at 18:04

WPF: ErrorMessage when trying to Bind a Line to two UIElements

1 Answers1