WPF 扩展列表框找不到定义

Question

扩展了 ListBox 给我一个水平列表框，即 XAML:

<ListBox x:Class="Renishaw.Inspire.InTheatreCompanion.View.HorizontalListBox"
         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         Style="{x:Null}">

    <ListBox.ItemsPanel>
        <ItemsPanelTemplate>
            <VirtualizingStackPanel Name="ItemContainer" 
                                    Orientation="Horizontal"/>
        </ItemsPanelTemplate>
    </ListBox.ItemsPanel>


</ListBox>

在后面的代码中

public partial class HorizontalListBox : ListBox
   {
      public static readonly DependencyProperty IndentItemsProperty = DependencyProperty.Register(
         "IndentItems", typeof(double), typeof(HorizontalListBox), new PropertyMetadata(0.0, new PropertyChangedCallback(OnIndentItemsChanged)));

      public HorizontalListBox()
      {
         InitializeComponent();
      }

      public double IndentItems
      {
         get { return (double)GetValue(IndentItemsProperty); }
         set { SetValue(IndentItemsProperty, value); }
      }

      private static void OnIndentItemsChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
      {
         var horizontalListBox = (HorizontalListBox)d;
         var thickness = new Thickness((double)e.NewValue, 0, 0, 0);
         horizontalListBox.ItemContainer.Margin = thickness;
      }

      public static void SetIndentItems(DependencyObject obj, double thickness)
      {
         obj.SetValue(IndentItemsProperty, thickness);
      }

      public static double GetIndentItems(DependencyObject obj)
      {
         return (double)obj.GetValue(IndentItemsProperty);
      }

   }

其中依赖项属性 IndentItems 允许我通过设置用于包含项目的 VirtualizingStackPanel 的边距来将项目缩进一定数量。然而，尝试构建它会抛出一个错误，告诉我 "HorizonatlListBox does not contain a definition for 'ItemContainer'"，即使它已在 xaml 中被赋予该名称。我有什么地方可能出错的想法吗？

Answer 1

为此使用转换器怎么样？

<Window x:Class="ListBoxMargins.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="clr-namespace:ListBoxMargins"
    Title="MainWindow" Height="350" Width="525">
<Grid>
    <Grid.Resources>
        <local:StackConverter x:Key="StackConverter"/>
    </Grid.Resources>
    <ListBox ItemsSource="{Binding source}">
        <ListBox.ItemsPanel>
            <ItemsPanelTemplate>
                <VirtualizingStackPanel Name="ItemContainer" 
                                Orientation="Horizontal" 
                                Margin="{Binding RelativeSource={RelativeSource Self}, Path=IsKeyboardFocusWithin, Converter={StaticResource StackConverter}}"/>
            </ItemsPanelTemplate>
        </ListBox.ItemsPanel>
    </ListBox>
</Grid>

public partial class MainWindow : Window
{
    public ObservableCollection<string> source { get; set; }
    public MainWindow()
    {
        InitializeComponent();
        source = new ObservableCollection<string>();
        source.Add("Test element1");
        source.Add("Test element2");
        source.Add("Test element3");
        this.DataContext = this;
    }
}

我没有在此处进行所有检查，但在我的测试中，面板是缩进的。

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

        if (focused)
        {
            return new Thickness(50);
        }
        else
        {
            return new Thickness(0);
        }
    }

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

Answer 2

在模板中设置元素的名称不会在 class 中生成声明模板的成员，即在您的 HorizontalListBox class 中没有 ItemContainer 成员。

除此之外，你的IndentItems 属性似乎是多余的，因为ListBox已经有一个Padding 属性:

<local:HorizontalListBox Padding="50,0,0,0" .../>

现在可能不再需要派生的 HorizontalListBox，因为您可以这样写：

<ListBox Padding="50,0,0,0" ...>
    <ListBox.ItemsPanel>
        <ItemsPanelTemplate>
            <VirtualizingStackPanel Orientation="Horizontal"/>
        </ItemsPanelTemplate>
    </ListBox.ItemsPanel>
<ListBox/>

Answer 3

您可以比创建新控件更简单地满足您的要求：

<App.Resources>
    <ItemsPanelTemplate x:Key="HorizontalStackPanelTemplate">
        <VirtualizingStackPanel Orientation="Horizontal" />
    <ItemsPanelTemplate>
</App.Resources>

<ListBox ItemsSource="{Binding source}" Padding ="50,0,0,0"
         ItemsPanel="{StaticResource HorizontalStackPanelTemplate}" />

WPF 扩展列表框找不到定义

WPF Extended ListBox doesn't find definition

wpf

xaml

listbox