/// <summary>
/// Returns the target type for a conversion operation.
/// </summary>
/// <param name="converterIndex">The index of the current converter about to be executed.</param>
/// <param name="finalTargetType">The 'targetType' argument passed into the conversion method.</param>
/// <param name="convert">Pass true if calling from the Convert method, or false if calling from ConvertBack.</param>
protected virtual Type GetTargetType(int converterIndex, Type finalTargetType, bool convert)
{
// If the current converter is not the last/first in the list,
// get a reference to the next/previous converter.
IValueConverter nextConverter = null;
if (convert)
{
if (converterIndex < Converters.Count - 1)
{
nextConverter = Converters[converterIndex + 1];
if (nextConverter == null)
{
throw new InvalidOperationException(
"The Converters collection of the ValueConverterGroup contains a null reference at index: "
+ (converterIndex + 1));
}
}
}
else
{
if (converterIndex > 0)
{
nextConverter = Converters[converterIndex - 1];
if (nextConverter == null)
{
throw new InvalidOperationException(
"The Converters collection of the ValueConverterGroup contains a null reference at index: "
+ (converterIndex - 1));
}
}
}
if (nextConverter != null)
{
ValueConversionAttribute conversionAttribute = cachedAttributes[nextConverter];
// If the Convert method is going to be called, we need to use the SourceType of the next
// converter in the list. If ConvertBack is called, use the TargetType.
return(convert ? conversionAttribute.SourceType : conversionAttribute.TargetType);
}
// If the current converter is the last one to be executed return the
// target type passed into the conversion method.
return(finalTargetType);
}
private object BackwardConverterCall(IValueConverter _converter, object _value, object _parameter, CultureInfo _culture)
{
if (_converter == null)
{
return(null);
}
object[] attribs = _converter.GetType().GetCustomAttributes(typeof(ValueConversionAttribute), false);
if (attribs != null && attribs.Length == 1)
{
ValueConversionAttribute vca = attribs[0] as ValueConversionAttribute;
if (vca != null)
{
Type currentSourceType = vca.SourceType;
return(_converter.ConvertBack(_value, currentSourceType, _parameter, _culture));
}
}
return(null);
}