将 IValueConverter 与 DynamicResource 一起使用吗？

Question

使用 DynamicResource 扩展时是否可以定义转换器？ 不幸的是，其中的一些内容

<RowDefinition Height="{Binding Source={DynamicResource someHeight}, Converter={StaticResource gridLengthConverter}}" />

给了我以下的期待：

“DynamicResourceExtension”不能 设置类型的“Source”属性 ‘绑定’。一个 “DynamicResourceExtension”只能是 设置在 a 的 DependencyProperty 上 依赖对象。

Answer 1

我知道我真的很晚了，但绝对有效的是使用 BindingProxy 对于像这样的 DynamicResource

<my:BindingProxy x:Key="someHeightProxy" Data="{DynamicResource someHeight}" />

然后将转换器应用到代理

<RowDefinition Height="{Binding Source={StaticResource someHeightProxy}, Path=Data, Converter={StaticResource gridLengthConverter}}" />

Answer 2

尝试类似的方法：

标记扩展：

public class DynamicResourceWithConverterExtension : DynamicResourceExtension
{
    public DynamicResourceWithConverterExtension()
    {
    }

    public DynamicResourceWithConverterExtension(object resourceKey)
            : base(resourceKey)
    {
    }

    public IValueConverter Converter { get; set; }
    public object ConverterParameter { get; set; }

    public override object ProvideValue(IServiceProvider provider)
    {
        object value = base.ProvideValue(provider);
        if (value != this && Converter != null)
        {
            Type targetType = null;
            var target = (IProvideValueTarget)provider.GetService(typeof(IProvideValueTarget));
            if (target != null)
            {
                DependencyProperty targetDp = target.TargetProperty as DependencyProperty;
                if (targetDp != null)
                {
                    targetType = targetDp.PropertyType;
                }
            }
            if (targetType != null)
                return Converter.Convert(value, targetType, ConverterParameter, CultureInfo.CurrentCulture);
        }

        return value;
    }
}

XAML：

<RowDefinition Height="{my:DynamicResourceWithConverter someHeight, Converter={StaticResource gridLengthConverter}}" />

Answer 3

@Thomas 的帖子非常接近，但正如其他人指出的那样，它仅在执行 MarkupExtension 时执行。

这是一个执行真正绑定的解决方案，不需要“代理”对象，并且编写方式与任何其他绑定一样，只是您给它一个资源密钥而不是源和路径...

如何创建支持转换器、StringFormat 的 DynamicResourceBinding？

Answer 4

我喜欢 mkoertgen 的回答。

下面是一个适用于我的 VB.NET 中 IValueConverter 代理的改编示例。我的资源“VisibilityConverter”现在作为 DynamicResource 包含并通过 ConverterProxy“VisibilityConverterProxy”转发。

用法：

...
xmlns:binding="clr-namespace:Common.Utilities.ModelViewViewModelInfrastructure.Binding;assembly=Common"
...
<ResourceDictionary>
    <binding:ConverterProxy x:Key="VisibilityConverterProxy" Data="{DynamicResource VisibilityConverter}" />
</ResourceDictionary>
...
Visibility="{Binding IsReadOnly, Converter={StaticResource VisibilityConverterProxy}}"

代码：

Imports System.Globalization

Namespace Utilities.ModelViewViewModelInfrastructure.Binding

''' <summary>
''' The ConverterProxy can be used to replace StaticResources with DynamicResources.
''' The replacement helps to test the xaml classes. See ToolView.xaml for an example
''' how to use this class.
''' </summary>
Public Class ConverterProxy
    Inherits Freezable
    Implements IValueConverter

#Region "ATTRIBUTES"

    'Using a DependencyProperty as the backing store for Data.  This enables animation, styling, binding, etc...
    Public Shared ReadOnly DataProperty As DependencyProperty =
                                DependencyProperty.Register("Data", GetType(IValueConverter), GetType(ConverterProxy), New UIPropertyMetadata(Nothing))

    ''' <summary>
    ''' The IValueConverter the proxy redirects to
    ''' </summary>
    Public Property Data As IValueConverter
        Get
            Return CType(GetValue(DataProperty), IValueConverter)
        End Get
        Set(value As IValueConverter)
            SetValue(DataProperty, value)
        End Set
    End Property

#End Region


#Region "METHODS"

    Protected Overrides Function CreateInstanceCore() As Freezable
        Return New ConverterProxy()
    End Function

    Public Function Convert(ByVal value As Object, ByVal targetType As Type, ByVal parameter As Object, ByVal culture As CultureInfo) As Object Implements IValueConverter.Convert
        Return Data.Convert(value, targetType, parameter, culture)
    End Function

    Public Function ConvertBack(ByVal value As Object, ByVal targetType As Type, ByVal parameter As Object, ByVal culture As CultureInfo) As Object Implements IValueConverter.ConvertBack
        Return Data.ConvertBack(value, targetType, parameter, culture)
    End Function

#End Region



End Class

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