在使用DynamicResource 扩展时，有没有办法定义转换器？
<RowDefinition Height="{Binding Source={DynamicResource someHeight}, Converter={StaticResource gridLengthConverter}}" />
不幸的是，这给了我以下异常：
“DynamicResourceExtension”不能 在类型的“源”属性上设置 '捆绑'。一种 'DynamicResourceExtension' 只能是 在 a 的 DependencyProperty 上设置 依赖对象。
【问题讨论】：
标签： wpf binding ivalueconverter dynamicresource
我知道我真的迟到了，但绝对有效的是使用 BindingProxy 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}}" />
【讨论】：
xmlns:my="clr-namespace:MyNamespace1.MyNamespace2" 编译并找到标记扩展，而 xmlns:my="clr-namespace:MyNamespace1.MyNamespace2;assembly=MyAssembly" 没有。
试试这样的：
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}}" />
【讨论】：
Unknown property 'Converter' for type 'MS.Internal.Markup.MarkupExtensionParser+UnknownMarkupExtension'
ProvideValue 由 XAML 解析器调用一次，不应转换任何内容。相反，它应该为依赖属性提供一些启用转换的东西。
@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。
这是一个真正绑定的解决方案，不需要“代理”对象，并且编写起来就像任何其他绑定一样，除了源和路径，你给它一个资源键......
How do you create a DynamicResourceBinding that supports Converters, StringFormat?
【讨论】：
我喜欢 mkoertgen 的回答。
这是一个适用于我的 VB.NET 中 IValueConverter 代理的改编示例。我的资源“VisibilityConverter”现在包含为 DynamicResource 并与 ConverterProxy“VisibilityConverterProxy”一起转发。
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
结束命名空间
【讨论】：