WPF 运行时区域设置更改，重新评估 ValueConverters UI

Question

在大型 WPF 应用程序中，我们可以在运行时更改语言。我们使用WPF Localize Extension 和 resx-files 进行本地化，效果很好，除了 UI 中使用的转换器。如果在绑定中 ValueConverter 是特定于文化的，则生成的文本不会随着语言的变化而更新。

如何让 WPF 在应用程序范围内更新所有已转换的绑定？

编辑：目前我们已经通过制作 ValueConverters MultiValueConverters 并将语言环境添加为额外值进行了实验。这样，值源值会发生变化，结果也会更新。但这既麻烦又丑陋。

<MultiBinding Converter="{StaticResource _codeMultiConverter}" ConverterParameter="ZSLOOPAKT">
  <Binding Path="ActivityCode" />
  <Binding Source="{x:Static lex:LocalizeDictionary.Instance}" Path="Culture" />
  <Binding Source="{x:Static RIEnums:CodeTypeInfo+CodeDisplayMode.Both}" />
</MultiBinding>

相关： Run-time culture change and IValueConverter in a binding （我没有为每个字段手动提升 propertychanged 的​​选项）

Answer 1

这是我们的解决方案。我希望我能理解您想要更改的问题，例如 DateTime?

Converter 是一个简单的IValueConverter，它将值转换为当前语言。 Translator 是一个静态类，它持有（例如）CurrentLanguage (en-en / de-de) 为 string。

如果语言已更改，则需要 Behavior 来更新绑定。在hole程序中我们只需要这个实现3-4次，因为它只针对DateTime格式。所有其他文本都保存在动态资源中..

但我认为Behavior 是适合您的需求。

转换器

public class CultureConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        if (value != null)
        {
            DateTime dateTime;
            if(DateTime.TryParse(value.ToString(), out dateTime))
            {
                if(parameter != null)
                {
                    return dateTime.ToString(parameter.ToString(), new CultureInfo(Translator.CurrentLanguage));
                }
                return dateTime.ToString(new CultureInfo(Translator.CurrentLanguage));
            }
            return null;
        }
        return null;
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        return null;
    }
}

行为

public class CultureConverter : Behavior<FrameworkElement>
{
    private FrameworkElement _HostingControl;
    private DependencyProperty _HostingControlDependencyProperty;

    protected override void OnAttached()
    {
        base.OnAttached();

        _HostingControl = AssociatedObject;

        _InitHostingControl();
        Translator.LanguageChanged += Translator_LanguageChanged;
    }

    protected override void OnDetaching()
    {
        Translator.LanguageChanged -= Translator_LanguageChanged;

        base.OnDetaching();
    }

    private void Translator_LanguageChanged(string languageCode)
    {
        if(_HostingControlDependencyProperty != null)
            _HostingControl.GetBindingExpression(_HostingControlDependencyProperty).UpdateTarget();
    }

    private void _InitHostingControl()
    {
        if(_HostingControl is TextBlock)
        {
            _HostingControlDependencyProperty = TextBlock.TextProperty;
        }
        else if (typeof(TextBox) == _HostingControl.GetType())
            _HostingControlDependencyProperty = TextBox.TextProperty;
    }

XAML

<Window.Resources>
    <XamlConverter:CultureConverter x:Key="CultureConverter"/>
<Window.Resources>


<DataGridTemplateColumn.CellTemplate>
    <DataTemplate>
        <TextBlock 
            Text="{Binding CreatedOn, ConverterParameter=f, Converter={StaticResource CultureConverter}, UpdateSourceTrigger=PropertyChanged}">
            <i:Interaction.Behaviors>
                <Behaviors:CultureConverter/>
            </i:Interaction.Behaviors>
        </TextBlock>
    </DataTemplate>
</DataGridTemplateColumn.CellTemplate>

预览

Answer 2

作为一个选项 - 您可以围绕 Binding 创建包装标记扩展，如下所示：

public class LocBindingExtension : MarkupExtension {
    public BindingBase Binding { get; set; }

    public override object ProvideValue(IServiceProvider serviceProvider) {
        if (Binding == null)
            return null;

        // Binding is by itself MarkupExtension
        // Call its ProvideValue
        var expression = Binding.ProvideValue(serviceProvider) as BindingExpressionBase;
        if (expression != null) {                
            // if got expression - create weak reference
            // you don't want for this to leak memory by preventing binding from GC
            var wr = new WeakReference<BindingExpressionBase>(expression);
            PropertyChangedEventHandler handler = null;
            handler = (o, e) => {                    
                if (e.PropertyName == nameof(LocalizeDictionary.Instance.Culture)) {
                    BindingExpressionBase target;
                    // when culture changed and our binding expression is still alive - update target
                    if (wr.TryGetTarget(out target))
                        target.UpdateTarget();
                    else
                        // if dead - unsubsribe
                        LocalizeDictionary.Instance.PropertyChanged -= handler;
                }

            };
            LocalizeDictionary.Instance.PropertyChanged += handler;
            return expression;
        }
        // return self if there is no binding target (if we use extension inside a template for example)
        return this;  
    }
}

这样使用：

<TextBlock Text="{my:LocBinding Binding={Binding ActivityCode, Converter={StaticResource myConverter}}}" />

您可以提供任何绑定（包括MultiBinding）并使用可以应用绑定的任何属性。

如果您认为即使这样也过于冗长 - 您可以以不同的方式包装绑定 - 通过在标记扩展上镜像您需要的 Binding 类的所有属性并将它们转发到底层绑定。在这种情况下，您将不得不编写更多代码，并且您需要为 Binding 和 MultiBinding 设置单独的类（以防您也需要 MultiBinding）。最好的方法是从Binding 继承并覆盖它的ProvideValue，但它不是虚拟的，所以不可能这样做，而且我没有找到任何其他可以覆盖的方法来实现结果。这是一个只有 2 个绑定属性的草图：

public class LocBindingExtension : MarkupExtension {
    private readonly Binding _inner;
    public LocBindingExtension() {
        _inner = new Binding();
    }

    public LocBindingExtension(PropertyPath path) {
        _inner = new Binding();
        this.Path = path;
    }

    public IValueConverter Converter
    {
        get { return _inner.Converter; }
        set { _inner.Converter = value; }
    }

    public PropertyPath Path
    {
        get { return _inner.Path; }
        set { _inner.Path = value; }
    }

    public override object ProvideValue(IServiceProvider serviceProvider) {            
        // Binding is by itself MarkupExtension
        // Call its ProvideValue
        var expression = _inner.ProvideValue(serviceProvider) as BindingExpressionBase;
        if (expression != null) {                
            // if got expression - create weak reference
            // you don't want for this to leak memory by preventing binding from GC
            var wr = new WeakReference<BindingExpressionBase>(expression);
            PropertyChangedEventHandler handler = null;
            handler = (o, e) => {                    
                if (e.PropertyName == nameof(LocalizeDictionary.Instance.Culture)) {
                    BindingExpressionBase target;
                    // when culture changed and our binding expression is still alive - update target
                    if (wr.TryGetTarget(out target))
                        target.UpdateTarget();
                    else
                        // if dead - unsubsribe
                        LocalizeDictionary.Instance.PropertyChanged -= handler;
                }

            };
            LocalizeDictionary.Instance.PropertyChanged += handler;
            return expression;
        }
        // return self if there is no binding target (if we use extension inside a template for example)
        return this;  
    }
}

然后用法被简化为：

<TextBlock Text="{my:LocBinding ActivityCode, Converter={StaticResource myConverter}}" />

您可以根据需要添加更多属性（如Mode 等）。