Question

我刚刚开始研究一个在listBox中显示一堆xml数据的应用程序，但问题不是每个xml项都有一个子值（在我的问题中，上传），所以它的listBox代码不应该'显示。

示例：

<item>
     <id>1</id>
     <body>Some text</body>
     <upload></upload>
     <created>Some text</created>
</item>

我正在获取数据并以这种方式填充我的列表：

var data = from query in loadedData.Descendants("item")
                   select new droppedItem
                   {
                       Id = (int)query.Element("id"),
                       Body = (string)query.Element("body"),
                       Upload = (string)query.Element("upload"),
                       Created = (DateTime)ConvertFromUnixTimestamp((double)query.Element("created"))
                   };
        userDrops.ItemsSource = data;

我的xaml看起来像：

<ListBox Margin="0,0,-12,0" Name="userDrops">
                <ListBox.ItemTemplate>
                    <DataTemplate>
                        <StackPanel Margin="0,0,0,17" Width="432">
                            <RichTextBox>
                                <Paragraph>
                                    <Run Text="{Binding Body}" FontSize="25" FontFamily="Segoe WP"></Run>
                                </Paragraph>
                                <Paragraph>
                                    <Hyperlink NavigateUri="{Binding Upload}" TargetName="_blank" FontSize="25" FontFamily="Segoe WP">{Binding Upload}</Hyperlink>
                                </Paragraph>
                                <Paragraph>
                                    <Run Text="{Binding Created}" FontFamily="Segoe WP SemiLight"></Run>
                                </Paragraph>
                            </RichTextBox>
                        </StackPanel>
                    </DataTemplate>
                </ListBox.ItemTemplate>
            </ListBox>

我想要做的只是显示包含上传信息的段落，如果xml上传子项包含值。否则，只需将其从listBox中删除即可。我不知道如何更改基本的listBox模板。

任何帮助都会很棒！

Answer 1

如何使用TextBlocks显示Body和Created？中间部分为RichTextBox，如果上传为空，您可以使用可见性转换器来切换隐藏/显示。

您需要首先在xaml页面中包含转换器，

xmlns:converters="clr-namespace:xxx.Converters;assembly=xxx"

<converters:VisibilityConverter x:Key="visibilityConverter" />

然后在模板中使用它，

                <StackPanel Margin="40,237,8,326" Width="432" Grid.Row="1"> 
                    <RichTextBox> 
                        <Paragraph> 
                            <Run Text="{Binding Body}" FontSize="25" FontFamily="Segoe WP"></Run> 
                        </Paragraph>
                    </RichTextBox> 
                    <RichTextBox Visibility="{Binding Upload, Converter={StaticResource VisibilityConverter}}">
                        <Paragraph> 
                            <Hyperlink NavigateUri="{Binding Upload}" TargetName="_blank" FontSize="25" FontFamily="Segoe WP">{Binding Upload}</Hyperlink> 
                        </Paragraph>
                    </RichTextBox> 
                        <TextBlock Text="{Binding Created}" FontFamily="Segoe WP SemiLight"/>
                </StackPanel>

转换器应该是这样的，

  public class VisibilityConverter : IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            bool visible = true;

            if (value is bool)
            {
                visible = (bool)value;
            }
            else if (value is int || value is short || value is long)
            {
                visible = 0 != (int)value;
            }
            else if (value is float || value is double)
            {
                visible = 0.0 != (double)value;
            }
            else if (value is string) {
                visible = ((string)value).Length > 0;
            }
            else if (value == null) {
                visible = false;
            }

            if ((string)parameter == "!")
            {
                visible = !visible;
            }

            return visible ? Visibility.Visible : Visibility.Collapsed;
        }

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

有关值转换器的详细信息，请参阅this。

<强>更新

在App.xaml中，执行此操作，

<Application xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
             xmlns:sg="http://schemas.stargategroup.com.au/2010/xaml/presentation" 
             xmlns:converters="clr-namespace:xxx.Converters"
             x:Class="xxx.Application.App">

    <Application.Resources>
        <ResourceDictionary>
            <converters:VisibilityConverter x:Key="VisibilityConverter" />

Windows Phone 7动态列表框模板

1 个答案: