WPF如何使用转换器进行多重绑定的子绑定？ [英] wpf how to use a converter for child bindings of multibinding?

问题描述

我需要对布尔型布尔属性进行多重绑定，但需要像例子中那样反转其中一些：

I need a multibinding of bunch boolean properties but with inversing some of these like an example:

<StackPanel>
    <StackPanel.IsEnabled>
        <MultiBinding Converter="{StaticResource BooleanAndConverter}">
            <Binding Path="IsInitialized"/>
            <Binding Path="IsFailed" Converter="{StaticResource InverseBooleanConverter}"/>
        </MultiBinding>
    </StackPanel.IsEnabled>
</StackPanel.IsEnabled>

但是我从 InverseBooleanConverter 并显示消息目标必须为布尔值。我的InverseBooleanConverter是：

But I got a InvalidOperationException from a InverseBooleanConverter with message "The target must be a boolean". My InverseBooleanConverter is:

[ValueConversion(typeof(bool), typeof(bool))]
public class InverseBooleanConverter : IValueConverter
{
    #region IValueConverter Members

    public object Convert(object value, Type targetType, object parameter,
        System.Globalization.CultureInfo culture)
    {
        if (targetType != typeof(bool))
            throw new InvalidOperationException("The target must be a boolean");

        return !(bool)value;
    }

    public object ConvertBack(object value, Type targetType, object parameter,
        System.Globalization.CultureInfo culture)
    {
        throw new NotSupportedException();
    }
    #endregion
}

和BooleanAndConverter为：

and BooleanAndConverter is:

public class BooleanAndConverter : IMultiValueConverter
{
    public object Convert(object[] values, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        return values.All(value => (!(value is bool)) || (bool) value);
    }

    public object[] ConvertBack(object value, Type[] targetTypes, object parameter, System.Globalization.CultureInfo culture)
    {
        throw new NotSupportedException("BooleanAndConverter is a OneWay converter.");
    }
}

那么，如何使用带有子绑定的转换器？

So, how to use a converters with child bindings?

推荐答案

无需检查 targetType ，只需检查 value 的类型传递给Convert方法。

There is no need to check the targetType, just check the type of value passed into Convert method.

public object Convert(object value, Type targetType, 
                      object parameter, System.Globalization.CultureInfo culture)
{
    if (!(value is bool))
        throw new InvalidOperationException("Value is not bool");

    return !(bool)value;
}

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