Custom localized BooleanConverter

Question

I am trying to implement localized BooleanConverter. Everything works well so far, but when you double click on the property next message is being shown:

"Object of type 'System.String' cannot be converted to type 'System.Boolean'."

I suppose the problem is in method CreateInstance of TypeConverter which has that boolean property.

public class BoolTypeConverter : BooleanConverter
{
    private readonly string[] values = { Resources.BoolTypeConverter_False, Resources.BoolTypeConverter_True };

    public override object ConvertTo(ITypeDescriptorContext context, CultureInfo culture, object value, Type destinationType)
    {
        if (destinationType == typeof(string) && value != null)
        {
            var valueType = value.GetType();

            if (valueType == typeof(bool))
            {
                return values[(bool)value ? 1 : 0];
            }
            else if (valueType == typeof(string))
            {
                return value;
            }
        }

        return base.ConvertTo(context, culture, value, destinationType);
    }

    public override object ConvertFrom(ITypeDescriptorContext context, CultureInfo culture, object value)
    {
        var stringValue = value as string;

        if (stringValue != null)
        {
            if (values[0] == stringValue)
            {
                return true;
            }
            if (values[1] == stringValue)
            {
                return false;
            }
        }

        return base.ConvertFrom(context, culture, value);
    }

    public override StandardValuesCollection GetStandardValues(ITypeDescriptorContext context)
    {
        return new StandardValuesCollection(values);
    }
}

Answer 1

The main problem of your code is you are overriding GetStandardValues incorrectly.

In fact you don't need to override GetStandardValues, just remove it and you will get expected result, that acts like original boolean converter while showing your desired strings:

When overriding GetStandardValues you should return a list of supported values of the type that you are creating converter for, then using the ConvertTo you provide string representation values and using ConvertFrom, provide a way to converting the type from string values.