Question

所以我有这段代码：

<Style TargetType="{x:Type TreeViewItem}">
    <Style.Resources>
        <Converters:GetElementTypeConverter x:Key="GetElementTypeConverter" />
    </Style.Resources>
    <Style.Triggers>
        <DataTrigger Binding="{Binding Path=., Converter={StaticResource GetElementTypeConverter}}" Value="{x:Type Models:ServerItem}">
            <Setter Property="CommandBehaviors:MouseDoubleClick.Command" Value="{Binding ConnectServer}" />
            <Setter Property="CommandBehaviors:MouseDoubleClick.CommandParameter" Value="{Binding Path=SelectedItem, RelativeSource={RelativeSource Self}}" />
            <Setter Property="Foreground" Value="Gray" />
        </DataTrigger>
        <DataTrigger Binding="{Binding Path=., Converter={StaticResource GetElementTypeConverter}}" Value="{x:Type Models:DatabaseItem}">
            <Setter Property="CommandBehaviors:MouseDoubleClick.Command" Value="{Binding ConnectDb}" />
            <Setter Property="CommandBehaviors:MouseDoubleClick.CommandParameter" Value="{Binding Path=SelectedItem, RelativeSource={RelativeSource Self}}" />
            <Setter Property="Foreground" Value="Red" />
        </DataTrigger>
    </Style.Triggers>
</Style>

它定义了树视图项的一些属性，但它不能完全起作用 - 我的意思是它设置了前景色，但是当我双击任何项时，它不会触发我的命令。

Answer 1

我认为这与您之前提出的问题有关。

使用此设置，您已经提到了我昨天提到的内容，请记住RelayCommand<T>需要在相关元素上而不是父虚拟机上。这就是为什么你可能看到Foreground属性工作正常而不是命令执行，因为DataContext寻找命令（ServerItem和DatabaseItem）实际上并没有定义命令ConnectServer和ConnectDb。
此外，我们不是设置两个触发器，而是将ConnectDb设置为默认值，并使用触发器为相关元素上的ConnectServer设置ServerItem。

现在要解决您的问题，您可以在ConnectServer中的ServerItem和ConnectDb命令中定义DatabaseItem命令，或者如果要将命令保留在DataContext中在TreeView中，使用RelativeSource绑定从TreeView中查找这些命令。

类似的东西（经过测试并且工作正常）：

<TreeView ItemsSource="{Binding ServerItems}">
  <TreeView.ItemContainerStyle>
    <Style TargetType="{x:Type TreeViewItem}">
      <Style.Resources>
        <CommandBehaviors:GetElementTypeConverter x:Key="GetElementTypeConverter" />
      </Style.Resources>
      <Setter Property="CommandBehaviors:MouseDoubleClick.Command"
              Value="{Binding Path=DataContext.ConnectDb,
                              RelativeSource={RelativeSource FindAncestor,
                                                              AncestorType={x:Type TreeView}}}" />
      <Setter Property="CommandBehaviors:MouseDoubleClick.CommandParameter"
              Value="{Binding Path=.}" />
      <Setter Property="Foreground"
              Value="Black" />
      <Style.Triggers>
        <DataTrigger Binding="{Binding Path=.,
                                        Converter={StaticResource GetElementTypeConverter}}"
                      Value="{x:Type CommandBehaviors:ServerItem}">
          <Setter Property="CommandBehaviors:MouseDoubleClick.Command"
                  Value="{Binding Path=DataContext.ConnectServer,
                                  RelativeSource={RelativeSource FindAncestor,
                                                                  AncestorType={x:Type TreeView}}}" />
          <Setter Property="Foreground"
                  Value="Tomato" />
        </DataTrigger>
      </Style.Triggers>
    </Style>
  </TreeView.ItemContainerStyle>
  <TreeView.ItemTemplate>
    <HierarchicalDataTemplate ItemsSource="{Binding Databases}">
      <TextBlock Text="{Binding}" />
    </HierarchicalDataTemplate>
  </TreeView.ItemTemplate>
</TreeView>

更新（修复了DoubleClick的递归TreeViewItem事件调用）

在您的班级MouseDoubleClick

开关：

public class MouseDoubleClick {

  ...

  private static void OnMouseDoubleClick(object sender, RoutedEventArgs e) {
    Control control = sender as Control;
    ICommand command = (ICommand)control.GetValue(CommandProperty);
    object commandParameter = control.GetValue(CommandParameterProperty);
    command.Execute(commandParameter);
  }
}

到

public class MouseDoubleClick {

  ...

  private static void OnMouseDoubleClick(object sender, RoutedEventArgs e) {
    Control control = sender as Control;
    var possibleTreeViewItem = sender as TreeViewItem;
    if (control == null || (possibleTreeViewItem != null && !possibleTreeViewItem.IsSelected))
      return;
    ICommand command = (ICommand)control.GetValue(CommandProperty);
    object commandParameter = control.GetValue(CommandParameterProperty);
    command.Execute(commandParameter);
  }
}

TreeViews上的附加属性

1 个答案: