Question

我有以下xaml：

<ListView x:Name="SomeClass_SomeListProperty">
    <ListView.ItemTemplate>
        <DataTemplate>
            <Grid>
                <Grid.ColumnDefinitions>
                    <ColumnDefinition Width="*"/>
                    <ColumnDefinition Width="Auto"/>
                </Grid.ColumnDefinitions>
                <WrapPanel VerticalAlignment="Center" HorizontalAlignment="Center">
                    <TextBlock Text="{Binding Type}"/> <!--This is a string-->
                    <TextBlock Text=": "/>
                    <TextBlock Text="{Binding Number}"/> <!--This is a long-->
                </WrapPanel>
                <Grid Grid.Column="1" HorizontalAlignment="Center">
                    <Grid.ColumnDefinitions>
                        <ColumnDefinition Width="Auto"/>
                        <ColumnDefinition Width="*"/>
                    </Grid.ColumnDefinitions>
                    <Image Stretch="None"
                      Source="{Binding BoolThatDependsOnType, 
                      Converter={StaticResource BoolToImageConverter}, 
                      ConverterParameter='large'}" />
                    <Button Grid.Column="1" Content="Settings"
                      cal:Message.Attach="MethodCallThatDependsOnType"/>
                </Grid>
            </Grid>
        </DataTemplate>
    </ListView.ItemTemplate>
</ListView>

我可以以某种方式绑定bool“BoolThatDependsOnType”，具体取决于Type的值吗？我遇到的问题是图像源的设置取决于某个bool是真还是假。我想选择要绑定的bool，具体取决于Type是否为特定列表项的“type1”，“type2”或“type3”。

Answer 1

在@Clemens的启发下，我使用IMultiValueConverter和MultiBinding来找到以下解决方案（并且没有变量和方法名称不是实际使用的:-)）。

public class TypeAndMultipleBoolsToImageConverter : IMultiValueConverter
    {
        public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
        {
            if (values == null) return new BitmapImage(new Uri("some/path.png", UriKind.Relative));
            bool isOk;
            switch (((string) values[0]).ToLower(culture))
            {
                case "type1":
                    isOk = (bool) values[1];
                    break;
                case "type2":
                    isOk = (bool) values[2];
                    break;
                case "type3":
                    isOk = (bool) values[3];
                    break;
                default:
                    return new BitmapImage(new Uri("/some/path.png", UriKind.Relative));
            }
            return ConvertBoolToImage(isOk);
        }

        private static BitmapImage ConvertBoolToImage(bool isOk)
        {
            return isOk
                ? new BitmapImage(new Uri("/some/ok/path.png", UriKind.Relative))
                : new BitmapImage(new Uri("/some/not/ok/path.png", UriKind.Relative));
        }

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

<Image Stretch="None">
    <Image.Source>
        <MultiBinding Converter="{StaticResource TypeAndMultipleBoolsToImageConverter}">
            <Binding Path="Type"/>
            <Binding Path="DataContext.IsType1Ok"
                     RelativeSource="{RelativeSource Mode=FindAncestor, AncestorType=UserControl}"/>
            <Binding Path="DataContext.IsType2Ok"
                     RelativeSource="{RelativeSource Mode=FindAncestor, AncestorType=UserControl}"/>
            <Binding Path="DataContext.IsType3Ok"
                     RelativeSource="{RelativeSource Mode=FindAncestor, AncestorType=UserControl}"/>
        </MultiBinding>
    </Image.Source>
</Image>

根据WPF中列表项属性的值更改绑定

1 个答案: