DataTemplate中的XAML TemplateBinding

Question

我正在为一个UWP应用程序创建一个模板化的控件，当我试图在一个嵌套的DataTemplate中绑定时遇到了一个问题。下面是我在Themes/Generic.xaml中的控件XAML：

<Style TargetType="local:EnhancedListView">
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="local:EnhancedListView">
                <Grid HorizontalAlignment="Stretch">
                    <Grid.Resources>
                        <DataTemplate x:Key="ListViewTemplate">
                            <Grid>
                                <Grid.ColumnDefinitions>
                                    <ColumnDefinition />
                                    <ColumnDefinition />
                                </Grid.ColumnDefinitions>
                                <CheckBox Visibility="{Binding RelativeSource={RelativeSource TemplatedParent}, Converter={StaticResource BooleanToVisibilityConverter}, Path=IsCheckModeEnabled}" Grid.Column="0" />
                                <TextBlock Text="{Binding}" Grid.Column="1" />
                            </Grid>
                        </DataTemplate>
                    </Grid.Resources>
                    <Grid.RowDefinitions>
                        <RowDefinition />
                        <RowDefinition />
                    </Grid.RowDefinitions>
                    <CheckBox Visibility="{Binding RelativeSource={RelativeSource TemplatedParent}, Converter={StaticResource BooleanToVisibilityConverter}, Path=IsCheckModeEnabled}" Grid.Row="0">Hello</CheckBox>
                    <ListView Grid.Row="1" ItemsSource="{TemplateBinding ItemsSource}" ItemTemplate="{StaticResource ListViewTemplate}" />
                </Grid>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

下面是我的实际控制/转换器：

public class EnhancedListView : Control
{
    public EnhancedListView()
    {
        DefaultStyleKey = typeof(EnhancedListView);
    }

    public object ItemsSource
    {
        get { return GetValue(ItemsSourceProperty); }
        set { SetValue(ItemsSourceProperty, value); }
    }

    public static readonly DependencyProperty ItemsSourceProperty = DependencyProperty.Register("ItemsSource", typeof(object), typeof(EnhancedListView), new PropertyMetadata(null));

    public bool IsCheckModeEnabled
    {
        get { return (bool)GetValue(IsCheckModeEnabledProperty); }
        set { SetValue(IsCheckModeEnabledProperty, value); }
    }

    public static readonly DependencyProperty IsCheckModeEnabledProperty = DependencyProperty.Register("IsCheckModeEnabled", typeof(bool), typeof(EnhancedListView), new PropertyMetadata(null));
}

public class BooleanToVisibilityConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, string language)
    {
        return (bool)value ? Visibility.Visible : Visibility.Collapsed;
    }

    public object ConvertBack(object value, Type targetType, object parameter, string language)
    {
        throw new NotSupportedException();
    }
}

下面是MainPage.xaml：

<local:EnhancedListView IsCheckModeEnabled="False" x:Name="ctlListView">
</local:EnhancedListView>

最后，我的MainPage.xaml.cs：

    public MainPage()
    {
        this.InitializeComponent();

        ctlListView.ItemsSource = new List<string> { "Item 1", "Item 2" };
    }

正如我所期望的那样，当页面加载时，第一个复选框是隐藏的，因为IsCheckModeEnabled为false，但是嵌套在DataTemplate中的所有复选框仍然可见。

我曾尝试按照建议的here将其包装到StaticResource中，但它不适用于某些复杂类型，例如在我的DataTemplate中嵌套另一个DataTemplate。

我确信绑定在这里的可见性属性上是不太正确的：

<CheckBox Visibility="{Binding RelativeSource={RelativeSource TemplatedParent}, Converter={StaticResource BooleanToVisibilityConverter}, Path=IsCheckModeEnabled}" Grid.Column="0" />

谢谢你的帮忙!

Answer 1

这只是一个猜测，但是这个怎么样：

<CheckBox Visibility="{Binding RelativeSource={RelativeSource Mode=FindAncestor,AncestorType=local:EnhancedListView}, Converter={StaticResource BooleanToVisibilityConverter}, Path=IsCheckModeEnabled}" DataContext="{Binding}" Grid.Column="0" />

顺便说一句:伙计，这太复杂了.

Answer 2

我相信我找到了一个“干净”的解决方案。我创建了一个新的EnhancedListViewItem类，它可以模拟EnhancedListView.上的属性，然后我独立于父EnhancedListView.对该EnhancedListViewItem进行分配和样式化。下面是我更新后的Generic.xaml：

<Style TargetType="local:EnhancedListView">
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="local:EnhancedListView">
                <Grid HorizontalAlignment="Stretch">
                    <Grid.RowDefinitions>
                        <RowDefinition />
                        <RowDefinition />
                    </Grid.RowDefinitions>
                    <CheckBox Visibility="{Binding RelativeSource={RelativeSource TemplatedParent}, Converter={StaticResource BooleanToVisibilityConverter}, Path=IsCheckModeEnabled}" Grid.Column="0" />
                    <ListView Grid.Row="1" ItemsSource="{TemplateBinding ItemsSource}" />
                </Grid>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

<Style TargetType="local:EnhancedListViewDataItem">
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="local:EnhancedListViewDataItem">
                <Grid HorizontalAlignment="Stretch">
                    <Grid.ColumnDefinitions>
                        <ColumnDefinition />
                        <ColumnDefinition />
                    </Grid.ColumnDefinitions>
                    <CheckBox Visibility="{Binding RelativeSource={RelativeSource TemplatedParent}, Converter={StaticResource BooleanToVisibilityConverter}, Path=IsCheckModeEnabled}" Grid.Column="0" />
                    <TextBlock Text="{Binding}" Grid.Column="1" />
                </Grid>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

下面是我更新后的控件代码：

public class EnhancedListView : Control, INotifyPropertyChanged
{
    public EnhancedListView()
    {
        DefaultStyleKey = typeof(EnhancedListView);
    }

    public event PropertyChangedEventHandler PropertyChanged;

    public object ItemsSource
    {
        get { return GetValue(ItemsSourceProperty); }
        set
        {
            var boundItems = new List<EnhancedListViewDataItem>();

            foreach (var obj in (List<string>)value)
            {
                boundItems.Add(new EnhancedListViewDataItem(this)
                {
                    DataContext = obj
                });
            }

            SetValue(ItemsSourceProperty, boundItems);
        }
    }

    public static readonly DependencyProperty ItemsSourceProperty = DependencyProperty.Register("ItemsSource", typeof(object), typeof(EnhancedListView), new PropertyMetadata(null));

    public bool IsCheckModeEnabled
    {
        get { return (bool)GetValue(IsCheckModeEnabledProperty); }
        set
        {
            SetValue(IsCheckModeEnabledProperty, value);
            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs("IsCheckModeEnabled"));
        }
    }

    public static readonly DependencyProperty IsCheckModeEnabledProperty = DependencyProperty.Register("IsCheckModeEnabled", typeof(bool), typeof(EnhancedListView), new PropertyMetadata(null));
}

public class EnhancedListViewDataItem : ListViewItem
{
    public EnhancedListViewDataItem(EnhancedListView listView)
    {
        _listView = listView;
        _listView.PropertyChanged += _listView_PropertyChanged;
        DefaultStyleKey = typeof(EnhancedListViewDataItem);
    }

    private readonly EnhancedListView _listView;

    private void _listView_PropertyChanged(object sender, PropertyChangedEventArgs e)
    {
        IsCheckModeEnabled = _listView.IsCheckModeEnabled;
    }

    public bool IsCheckModeEnabled
    {
        get { return (bool)GetValue(IsCheckModeEnabledProperty); }
        set { SetValue(IsCheckModeEnabledProperty, value); }
    }

    public static readonly DependencyProperty IsCheckModeEnabledProperty = DependencyProperty.Register("IsCheckModeEnabled", typeof(bool), typeof(EnhancedListViewDataItem), new PropertyMetadata(null));
}