internal static IMultiValueConverter AssertConvert <TConvertedValue>(this IMultiValueConverter converter, object[] values, object parameter, TConvertedValue expectedConvertedValue, bool twoWay = false, bool backOnly = false, CultureInfo culture = null)
{
Assert.That(converter?.Convert(values, typeof(TConvertedValue), parameter, culture), Is.EqualTo(backOnly ? BindableProperty.UnsetValue : expectedConvertedValue));
var convertedBackValues = converter?.ConvertBack(expectedConvertedValue, null, parameter, culture);
if (twoWay || backOnly)
{
Assert.That(convertedBackValues.Length, Is.EqualTo(values.Length));
for (int i = 0; i < values.Length; i++)
{
Assert.That(convertedBackValues[i], Is.EqualTo(values[i]));
}
}
else
{
Assert.That(convertedBackValues, Is.Null);
}
return(converter);
}
/// <summary>
/// Converts a value by iterating in reverse order through the <see cref="Converters"/> collection and executing <see cref="IValueConverter.ConvertBack"/> method for each <see cref="IValueConverter"/> contained, next executing <see cref="IMultiValueConverter.ConvertBack"/> method of the <see cref="Converter"/>. The return value of the <see cref="IValueConverter.ConvertBack"/> method call for current <see cref="IValueConverter"/> in the iteration is passed as input value for processing next <see cref="IValueConverter"/> in the iteration or processing the <see cref="Converter"/>.
/// </summary>
/// <param name="value">The value that is produced by the binding target.</param>
/// <param name="targetTypes">The array of types to convert to. The array length indicates the number and types of values that are suggested for the method to return.</param>
/// <param name="parameter">The converter parameter to use.</param>
/// <param name="culture">The culture to use in the converter.</param>
/// <returns>An array of values that have been converted from the target value back to the source values, meaning the result of processing the reversed chain of converters.</returns>
public object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture)
{
IMultiValueConverter converter = Converter;
if (converter != null)
{
for (int i = converters.Count - 1; i >= 0; i--)
{
value = converters[i].ConvertBack(value, typeof(object), parameter, culture);
if (value == Binding.DoNothing)
{
return(null);
}
}
return(converter.ConvertBack(value, targetTypes, parameter, culture));
}
return(null);
}
/// <summary>
/// 绑定多个指定的值到属性，并使用指定的转换器。
/// </summary>
/// <param name="value">绑定的值。</param>
/// <param name="converter">更新时，值转换器。</param>
/// <param name="convertParameter">转换参数。</param>
/// <param name="culture">区域信息。</param>
/// <returns>返回已绑定的 <see cref="Forms.Binding"/> 实例。</returns>
/// <exception cref="ArgumentException">给定数据为null时引发。</exception>
/// <exception cref="ArgumentNullException">控件属性是已绑定到数据或<see cref="Forms.Binding"/> 未指定的有效列时引发。</exception>
public IBindableProperty Binding(MultiBindableValue value, IMultiValueConverter converter, object convertParameter = null, CultureInfo culture = null)
{
BindingCore(value, i => converter.Convert((object[])i, bindingProperty.PropertyType, converter, culture), i => converter.ConvertBack(i, value.ValueTypes, convertParameter, culture));
return(this);
}
public void TestName()
{
Assert.Throws <NotImplementedException>(() =>
_converter.ConvertBack("ThomasTheTankEngine", null, null, null)
);
}
