如何获得ListViewItem的索引？

Question

我有一个使用集合源的列表视图，并希望根据其在列表中的索引是否匹配视图模型中的值来设置ListViewItems的背景色。为此，我将listVeiwItem的背景绑定到ViewModel中的值，并使用转换器确定背景颜色。为此，需要将ListViewItem的索引传递给转换器。如何使用XAML获取索引？

下面是ListView使用的数据模板的XAML：

<DataTemplate x:Key="ILMemberTemplate">
    <StackPanel Orientation="Horizontal" Background="{Binding Path=ListIndex, Mode=OneWay, Converter={StaticResource ParticipantBackground}, ConverterParameter={???}}">
        <TextBlock
            Width="200"
            TextAlignment="Left"
            Foreground="{Binding Path=IsPC, Mode=OneWay, Converter={StaticResource ParticipantColour}}"
            Text="{Binding Path=Name, Mode=OneWay}"/>
        <TextBlock
            Width="40"
            TextAlignment="Center"
            Foreground="{Binding Path=IsPC, Mode=OneWay, Converter={StaticResource ParticipantColour}}"
            Text="{Binding Path=Initiative, Mode=OneWay}"/>
    </StackPanel>
</DataTemplate>

Answer 1

无法在XAML中获取索引并将其作为ConverterParameter传递。这是不可能的但是您可以使用多个转换器并绑定到ListIndex和父ListViewItem容器，例如：

class MultiConverter : IMultiValueConverter
{
    public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
    {
        var listIndex = values[0];
        //...
        ListViewItem item = value as ListViewItem;
        ListView lv = FindParent<ListView>(item);
        ICollectionView view = lv.ItemsSource as ICollectionView;
        IEnumerator e = view.GetEnumerator();
        int index = 0;
        while (e.MoveNext())
        {
            if (Equals(item.DataContext, e.Current))
                return index;
            else
                index++;
        }

        //return some brush based on the indexes..
    }

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

    private static T FindParent<T>(DependencyObject dependencyObject) where T : DependencyObject
    {
        var parent = VisualTreeHelper.GetParent(dependencyObject);

        if (parent == null) return null;

        var parentT = parent as T;
        return parentT ?? FindParent<T>(parent);
    }
}

XAML:

<DataTemplate x:Key="ILMemberTemplate">
    <StackPanel Orientation="Horizontal">
        <StackPanel.Background>
            <MultiBinding Converter="{StaticResource multiConverter}">
                <Binding Path="ListIndex" />
                <Binding Path="." RelativeSource="{RelativeSource AncestorType=ListViewItem}" />
            </MultiBinding>
        </StackPanel.Background>
        <!-- ... -->
    </StackPanel>
</DataTemplate>