public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
if (value == null || !(value is TimeSpan))
return string.Empty;
var span = (TimeSpan)value;
if (parameter == null || string.CompareOrdinal(parameter.ToString(), "full") != 0)
return FormatAsHoursAndMinutes(span);
return FormatAsCompleteUnits(span);
}