Binding ConverterParameter

问题:

Is there a way I could do this in a Style:

<Style TargetType=\"FrameworkElement\">
    <Setter Property=\"Visibility\">
        <Setter.Value>
            <Binding Path=\"Tag\"
                RelativeSource=\"{RelativeSource AncestorType=UserControl}\"
                Converter=\"{StaticResource AccessLevelToVisibilityConverter}\"
                ConverterParameter=\"{Binding RelativeSource={RelativeSource Mode=Self}, Path=Tag}\" />                        
        </Setter.Value>
    </Setter>
</Style>

I simply need to send the Tag of top-level parent and the Tag of control itself to my converter class.

回答1:

The ConverterParameter property can not be bound because it is not a dependency property.

Since Binding is not derived from DependencyObject none of its properties can be dependency properties. As a consequence, a Binding can never be the target object of another Binding.

There is however an alternative solution. You could use a MultiBinding with a multi-value converter instead of a normal Binding:

<Style TargetType=\"FrameworkElement\">
    <Setter Property=\"Visibility\">
        <Setter.Value>
            <MultiBinding Converter=\"{StaticResource AccessLevelToVisibilityConverter}\">
                <Binding Path=\"Tag\" RelativeSource=\"{RelativeSource Mode=FindAncestor,
                                                     AncestorType=UserControl}\"/>
                <Binding Path=\"Tag\" RelativeSource=\"{RelativeSource Mode=Self}\"/>
            </MultiBinding>
        </Setter.Value>
    </Setter>
</Style>

The multi-value converter gets an array of source values as input:

public class AccessLevelToVisibilityConverter : IMultiValueConverter
{
    public object Convert(
        object[] values, Type targetType, object parameter, CultureInfo culture)
    {
        return values.All(v => (v is bool && (bool)v))
            ? Visibility.Visible
            : Visibility.Hidden;
    }

    public object[] ConvertBack(
        object value, Type[] targetTypes, object parameter, CultureInfo culture)
    {
        throw new NotSupportedException();
    }
}

回答2:

No, unfortunately this will not be possible because ConverterParameter is not a DependencyProperty so you won\'t be able to use bindings

But perhaps you could cheat and use a MultiBinding with IMultiValueConverter to pass in the 2 Tag properties.