Question

我是winRT的新手并且在这方面苦苦挣扎。

我创建了一个DemoViewModel，我在其中声明了如下所示的DemoClickCommand。该命令的类型为DelegateCommand。

public DelegateCommand DemoClickCommand { get; private set; }

protected virtual void OnClickCommandExecuted(object parameter)
    {
      var obj = parameter;
    }

    protected virtual bool OnClickCommandCanExecute(object parameter)
    {
      return true;
    }

public DemoViewModel()
    {
      this.DemoClickCommand = new DelegateCommand(this.OnClickCommandExecuted, this.OnClickCommandCanExecute);
    }

我已将此命令绑定到我的表单上的一个按钮，该按钮本身可以正常工作但在包含在使用datatemplate的listView中时不起作用。

 <Grid Background="{StaticResource ApplicationPageBackgroundThemeBrush}">
<!-- THIS BUTTON WORKS FINE-->    
<Button Content="Button"
            HorizontalAlignment="Left"
            Height="143"
            Margin="1354,424,0,0"
            VerticalAlignment="Top"
            Width="307"
            Background="#FFC11A1A"
            FontSize="36"
            Command="{Binding DemoClickCommand, Mode=OneWay}" />
<!-- THIS LISTVIEW WHICH USES THE DATATEMPLATE WONT WORK -->
    <ListView x:Name="lvDemoItems"
              SelectionChanged="lvDemoItems_SelectionChanged"
              Grid.Column="0"
              Margin="0,140,0,0"
              ItemTemplate="{StaticResource DemoTemplate}"
              ItemsSource="{Binding DemoItems}"
              SelectionMode="Single"
              HorizontalAlignment="Left"
              Width="904">
    </ListView>

  </Grid>

这是我的页面资源中定义的数据模板

<Page.Resources>
    <DataTemplate x:Name="DemoTemplate">
      <Grid Height="110"
            Width="480"
            Margin="10">
        <Grid.ColumnDefinitions>
          <ColumnDefinition Width="Auto" />
          <ColumnDefinition Width="*" />
        </Grid.ColumnDefinitions>
        <Border Background="{StaticResource ListViewItemPlaceholderBackgroundThemeBrush}"
                Width="110"
                Height="110">
          <Image Source="{Binding ImageURI}"
                 Stretch="UniformToFill"
                 AutomationProperties.Name="{Binding Title}" />
        </Border>
        <StackPanel Grid.Column="1"
                    VerticalAlignment="Top"
                    Margin="10,0,0,0">
          <TextBlock Text="{Binding Name}"
                     Style="{StaticResource TitleTextStyle}"
                     TextWrapping="NoWrap" />
          <TextBlock Text="{Binding Description}"
                     Style="{StaticResource BodyTextStyle}"
                     MaxHeight="160" />
          <Button Content="Edit"
                  BorderBrush="Black"
                  Background="Green"
                  Height="40"
                  Width="80"
                  Margin="0,20,0,0"
                  Command="{Binding DemoClickCommand, Mode=OneWay}"
                  CommandParameter="{Binding ID}" />
        </StackPanel>
      </Grid>
    </DataTemplate>

  </Page.Resources>

我认为我需要使用附加依赖属性但不确定如何实现它。

这是我到目前为止所做的，但我不知道如何使其发挥作用。你能帮忙解释一下吗？感谢

public ICommand DemoClickCommand { get; private set; }

    public static readonly DependencyProperty DemoClickCommand =
        DependencyProperty.RegisterAttached("DemoClickCommand", typeof(ICommand), typeof(Button), new PropertyMetadata(null, OnItemCommandPropertyChanged));

    private static void OnClickCommandPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
      ICommand command = e.NewValue as ICommand;
    }

Answer 1

在从底部到顶部完成的WPF值继承中。例如，当您将特定字体设置为堆栈面板时，堆栈面板内的所有子控件默认情况下将获得相同的字体。在带有datatemplate的代码段中，你有一个绑定到DemoClickCommand的Button，它是ListView控件的子代，其中ItemsSource是 DemoItems 。 DemoItems没有名为DemoClickCommand的属性。所以你需要明确提到按钮的祖先类型。请在您的DataTemplate代码中尝试以下XAML代码段

<Button Content="Edit"
              BorderBrush="Black"
              Background="Green"
              Height="40"
              Width="80"
              Margin="0,20,0,0"
              Command="{Binding Path=DemoClickCommand, Mode=OneWay, RelativeSource={RelativeSource AncestorType={x:Type Window}}}}"
              CommandParameter="{Binding ID}" />

或者您可以使用BindingElementName属性执行相同操作。为您的ManGrid命名并使用

<Button Content="Edit"
          BorderBrush="Black"
          Background="Green"
          Height="40"
          Width="80"
          Margin="0,20,0,0"
          Command="{Binding ElementName="MyGrid" Path=DemoClickCommand, Mode=OneWay}"
          CommandParameter="{Binding ID}" />

CommandParameter在ListView中不起作用

1 个答案: