如何在静态资源上设置依赖属性？ [英] How can I set a dependency property on a static resource?

问题描述

我想解决一个事实，即我不能为 ConverterParameter 指定动态值。 查看我的其他问题，为什么我需要将动态值绑定到 ConverterParameter - 我不喜欢目前发布的解决方案，因为它们都需要我觉得应该是我的View Model不必要的更改。

要尝试解决这个问题，我已经创建了一个自定义转换器，并在该转换器上暴露了依赖属性：

  public class InstanceToBooleanConverter：DependencyObject，IValueConverter 
 {
 public object Value 
 {
 get {return（object）GetValue（ValueProperty）; } 
 set {SetValue（ValueProperty，value）; } 
 
 
 public static readonly DependencyProperty ValueProperty = 
 DependencyProperty.Register（Value，typeof（object），typeof（InstanceToBooleanConverter），null）; 
 
 public object Convert（object value，Type targetType，object parameter，System.Globalization.CultureInfo culture）
 {
 return value！= null&& value.Equals（Value）; 
 
 
 public object ConvertBack（object value，Type targetType，object parameter，System.Globalization.CultureInfo culture）
 {
 return value.Equals（true）？价值：Binding.DoNothing; 
} 
} 
  

有没有办法使用绑定设置此值（或风格设定者或其他疯狂方法）在我的XAML？

 < ItemsControl ItemsSource ={Binding Properties}> ; 
< ItemsControl.ItemTemplate> 
< DataTemplate DataType ={x：Type local：SomeClass}> 
< DataTemplate.Resources> 
<！ - 我想从ItemsSource  - >中的项目设置Value 
< local：InstanceToBooleanConverter x：Key =converterValue ={Binding Path = ???}/> 
< /DataTemplate.Resources> 
<！ -  ...  - > 
  

到目前为止，我看到的示例只绑定到静态资源。

编辑：

我收到一些反馈，表示只有一个转换器实例与我发布的XAML。 / p>

我可以通过将资源置于我的控制范围内来解决：

 < ItemsControl ItemsSource ={Binding Properties}> 
< ItemsControl.ItemTemplate> 
< DataTemplate DataType ={x：Type local：SomeClass}> 
< RadioButton Content ={Binding Name}GroupName =Properties> 
< RadioButton.Resources> 
<！ - 我想从ItemsSource  - >中的项目设置Value 
< local：InstanceToBooleanConverter x：Key =converter
 Value ={Binding Path = ???}/> 
< /RadioButton.Resources> 
< RadioButton.IsChecked> 
< Binding Path =DataContext.SelectedItem
 RelativeSource ={RelativeSource AncestorType = {x：Type Window}}
 Converter ={StaticResource converter}/> 
< /RadioButton.IsChecked> 
< / RadioButton> 
<！ -  ...  - > 
  

所以这个问题不被阻止，因为不必共享转换器的一个实例：）

解决方案

首先，您可以在更高级别的资源字典中指定转换器，并设置 x：共享 到 false ，其次如果你想注释中的将项目从ItemsSource 设置为，你可以指定一个空的绑定（ Value ={Binding}）。

I'm trying to get around the fact that I can't specify a dynamic value for ConverterParameter. See my other question for why I need to bind a dynamic value to ConverterParameter - I don't like the solutions currently posted because they all require what I feel should be unnecessary changes to my View Model.

To attempt to solve this, I have created a custom converter, and exposed a dependency property on that converter:

public class InstanceToBooleanConverter : DependencyObject, IValueConverter
{
    public object Value
    {
        get { return (object)GetValue(ValueProperty); }
        set { SetValue(ValueProperty, value); }
    }

    public static readonly DependencyProperty ValueProperty =
        DependencyProperty.Register("Value", typeof(object), typeof(InstanceToBooleanConverter), null);

    public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        return value != null && value.Equals(Value);
    }

    public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        return value.Equals(true) ? Value : Binding.DoNothing;
    }
}

Is there a way to set this value using a binding (or style setter, or other crazy method) in my XAML?

<ItemsControl ItemsSource="{Binding Properties}">
    <ItemsControl.ItemTemplate>
        <DataTemplate DataType="{x:Type local:SomeClass}">
            <DataTemplate.Resources>
                <!-- I'd like to set Value to the item from ItemsSource -->
                <local:InstanceToBooleanConverter x:Key="converter" Value="{Binding Path=???}" />
            </DataTemplate.Resources>
<!- ... ->

The examples I've seen so far only bind to static resources.

Edit:

I got some feedback that there is only one converter instance with the XAML I posted.

I can work around this by placing the resource in my control:

<ItemsControl ItemsSource="{Binding Properties}">
    <ItemsControl.ItemTemplate>
        <DataTemplate DataType="{x:Type local:SomeClass}">
            <RadioButton Content="{Binding Name}" GroupName="Properties">
                <RadioButton.Resources>
                    <!-- I'd like to set Value to the item from ItemsSource -->
                    <local:InstanceToBooleanConverter x:Key="converter"
                                                      Value="{Binding Path=???}" />
                </RadioButton.Resources>
                <RadioButton.IsChecked>
                    <Binding Path="DataContext.SelectedItem"
                             RelativeSource="{RelativeSource AncestorType={x:Type Window}}"
                             Converter="{StaticResource converter}" />
                </RadioButton.IsChecked>
            </RadioButton>
<!- ... ->

So this problem isn't blocked by having to share an instance of the converter :)

解决方案

Firstly you can specify the converter at a higher level resource dictionary and set x:Shared to false, secondly if you want to "set the Value to the item from ItemsSource" as you annotated you can just specify an empty binding (Value="{Binding}").

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