如果ONE展开,则多个扩展器必须折叠

Question

有4个Expander控件.当一个扩展器扩展时,我怎么能让所有其他扩展器崩溃/关闭？

Answer 1

试试下面的代码:

XAML:

        <StackPanel Name="StackPanel1">
            <StackPanel.Resources>
                <local:ExpanderToBooleanConverter x:Key="ExpanderToBooleanConverter" />
            </StackPanel.Resources>
            <Expander Header="Expander 1"
                      IsExpanded="{Binding SelectedExpander, Mode=TwoWay, Converter={StaticResource ExpanderToBooleanConverter}, ConverterParameter=1}">
                <TextBlock>Expander 1</TextBlock>
            </Expander>
            <Expander Header="Expander 2"
                      IsExpanded="{Binding SelectedExpander, Mode=TwoWay, Converter={StaticResource ExpanderToBooleanConverter}, ConverterParameter=2}">
                <TextBlock>Expander 2</TextBlock>
            </Expander>
            <Expander Header="Expander 3"
                      IsExpanded="{Binding SelectedExpander, Mode=TwoWay, Converter={StaticResource ExpanderToBooleanConverter}, ConverterParameter=3}">
                <TextBlock>Expander 3</TextBlock>
            </Expander>
            <Expander Header="Expander 4"
                      IsExpanded="{Binding SelectedExpander, Mode=TwoWay, Converter={StaticResource ExpanderToBooleanConverter}, ConverterParameter=4}">
                <TextBlock>Expander 4</TextBlock>
            </Expander>
        </StackPanel>

转换器:

public class ExpanderToBooleanConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        return (value == parameter);
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        if (System.Convert.ToBoolean(value)) return parameter;
        return null;
    }
}

视图模型:

public class ExpanderListViewModel
{
    public Object SelectedExpander { get; set; }
}

初始化

StackPanel1.DataContext = new ExpanderListViewModel();

说明:

在XAML中,我们有4个扩展器.他们都继承ViewModel(类型ExpanderListViewModel从容器)StackPanel通过DataContext.

它们都绑定到ViewModel类上的单个属性.并且已经ConverterParameter在绑定中为自己定义了唯一索引.SelectedExpander每当展开扩展器时,该索引都会保存在属性中.并使用该索引,如果存储的索引与给定的索引匹配,并且存储的索引不匹配,则Converter返回.truefalse

放入断点Convert和类的ConvertBack方法,Converter你会看到发生了什么.