在我的WinForms应用程序，我实现的自定义数据与支持的价值转换器结合，类似WPF。

In my WinForms application I implemented custom data binding with support for value converters, similar to WPF.

该样品具有派生自绑定，并允许附加自定义转换一个新的绑定类：

The sample has a new binding class that derives from Binding and allows to attach a custom converter:

public class CustomBinding : Binding
{
    private readonly IValueConverter _converter;
    private readonly object _converterParameter;
    private readonly CultureInfo _converterCulture;

    public CustomBinding(string propertyName, object dataSource, string dataMember, IValueConverter valueConverter, CultureInfo culture, object converterParameter = null)
        : base(propertyName, dataSource, dataMember)
    {
        if (valueConverter != null)
            this._converter = valueConverter;

        this.DataSourceUpdateMode = DataSourceUpdateMode.OnPropertyChanged;
        this.FormattingEnabled = false;

        this._converterCulture = culture;
        this._converterParameter = converterParameter;
    }

    public CustomBinding(string propertyName, object dataSource, string dataMember, IValueConverter valueConverter, object converterParameter = null)
        : base(propertyName, dataSource, dataMember)
    {
        if (valueConverter != null)
            this._converter = valueConverter;

        this._converterCulture = Thread.CurrentThread.CurrentUICulture;
        this._converterParameter = converterParameter;
    }

    protected override void OnFormat(ConvertEventArgs cevent)
    {
        if (this._converter != null)
        {
            var converterdValue = this._converter.Convert(cevent.Value, cevent.DesiredType, _converterParameter, _converterCulture);
            cevent.Value = converterdValue;
        }
        else base.OnFormat(cevent);
    }

    protected override void OnParse(ConvertEventArgs cevent)
    {
        if (this._converter != null)
        {
            var converterdValue = this._converter.ConvertBack(cevent.Value, cevent.DesiredType, _converterParameter, _converterCulture);
            cevent.Value = converterdValue;
        }
        else base.OnParse(cevent);
    }
}

还有一个接口的IValueConverter 类似于WPF界面：

There is also the interface IValueConverter that is similar to the interface of WPF:

public interface IValueConverter
{
    object Convert(object value, Type targetType, object parameter, CultureInfo culture);
    object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture);
}

有了这个，我可以附加一个自己的转换器的任何（双向）绑定。到目前为止，我已经建立了一个 TimeSpanStringValueConverter ，让我一个时间跨度字段绑定到一个文本框，以及一个 InvertBooleanValueConverter 为布尔场对面绑定到任何控件的任何布尔属性。他们的工作如预期！

With this I'm able to attach an own converter to any (two-way) binding. So far I've built a TimeSpanStringValueConverter that allows me to bind a TimeSpan field to a textbox as well as a InvertBooleanValueConverter to bind the opposite of a boolean field to any boolean property of any control. They work as expected!

现在我要绑定类型的属性翻番？来一个文本框文本字段。为此，我写了这个转换器：

Now I want to bind a property of the type double? to a textbox Text field. For this I wrote this converter:

public class NullableDoubleStringValueConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        return value != null ? ((double)value).ToString(culture) : String.Empty;
    }

    public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        string text = Regex.Replace((string)value, @"[^0-9" + culture.NumberFormat.NumberDecimalSeparator + @"]", "");
        if (text == String.Empty)
        {
            return null;
        }
        double convertedValue;
        if (Double.TryParse(text, NumberStyles.Any, culture, out convertedValue))
        {
            return (double?)convertedValue;
        }
        return null;
    }
}

和我这样绑定到文本框：

And I bind it to the textbox this way:

this.textBox1.DataBindings.Add(new CustomBinding("Text", obj, "MyProperty", new NullableDoubleStringValueConverter())); // obj is the data context object

当我设置的值转换器，我可以清楚地看到我的字符串离开文本框后，将被转换为可空双重价值的 ConvertBack 方法一个破发点，成功。然而，代替我的其他情况下，将不更新该数据上下文对象。如果我在我的价值转换器的转换方法，设置一个断点，我可以看到它会获取 myProperty的离开它之后更新文本框的文本时，这是空。所以，我的文本框中键入任何数值后变空。

public CustomBinding(string propertyName, object dataSource, string dataMember, IValueConverter valueConverter, object converterParameter = null)
    : this(propertyName, dataSource, dataMember, valueConverter, Thread.CurrentThread.CurrentUICulture, converterParameter)
{ }

public CustomBinding(string propertyName, object dataSource, string dataMember, IValueConverter valueConverter, CultureInfo culture, object converterParameter = null)
    : base(propertyName, dataSource, dataMember, true)
{
    this._converter = valueConverter;
    this._converterCulture = culture;
    this._converterParameter = converterParameter;
}

this.DataSourceUpdateMode = DataSourceUpdateMode.OnPropertyChanged;

public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
    var text = value != null ? ((string)value).Trim() : null;
    return !string.IsNullOrEmpty(text) ? (object)double.Parse(text, NumberStyles.Any, culture) : null;
}