Question

我需要将我的按钮控件从下面替换为Expander控件。

comments_id

我不知道如何将Command添加到Expander控件，因此当展开Expander时，我想使用参数gridAdvanced执行AdvancedCommand。

如何以最好的方式实现这一目标？

感谢。

Answer 1

使用Expanded事件：

<Expander Expanded="Expander_Expanded" />

然后从后面的代码中调用命令：

private void Expander_Expanded(object sender, RoutedEventArgs e)
{
    ViewModel vm = (ViewModel)DataContext;
    if (vm.AdvancedCommand.CanExecute(vm.gridAdvances))
        vm.AdvancedCommand.Execute(vm.gridAdvances));
}

将ViewModel更改为DataContext所属的任何类型。

Answer 2

添加对System.Windows.Interactivity.dll的引用（在Visual Studio中是Project-> Add Reference-> Assemblies-> Extensions），并将交互触发器添加到Expander：

<Expander xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity">
    <i:Interaction.Triggers>
        <i:EventTrigger EventName="IsExpanded" >
            <i:InvokeCommandAction Command="{Binding AdvancedCommand}" CommandParameter="{Binding ElementName=gridAdvances}" />
        </i:EventTrigger>
    </i:Interaction.Triggers>
</Expander>

Answer 3

我建议将mm8的解决方案与Freggar建议的事件 Expanded 一起使用

<UserControl
xmlns:i="clr-amespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity"/>
   <Expander>
       <i:Interaction.Triggers>
           <i:EventTrigger EventName="Expanded" >
              <i:InvokeCommandAction Command="{Binding AdvancedCommand}" CommandParameter="{Binding ElementName=gridAdvances}" />
           </i:EventTrigger>
       </i:Interaction.Triggers>
   </Expander>
<UserControl>

Answer 4

我遇到了同样的问题，由于某种原因，无法对TreeView对象（.net core 3 + wpf）中的附加属性进行简单的事件触发。

<i:Interaction.Triggers>
  <i:EventTrigger EventName="Expander.Expand">
    <i:InvokeCommandAction Command="{Binding MyCommand}"/>
  </i:EventTrigger>
</i:Interaction.Triggers>

我必须通过自定义行为类来解决它。请参见下面的灵感;）

public class TreeViewSelectionBehavior : Behavior<TreeView>
{
    public object SelectedItem
    {
        get { return (object)GetValue(SelectedItemProperty); }
        set { SetValue(SelectedItemProperty, value); }
    }

    public ICommand Command
    {
        get { return (ICommand)GetValue(CommandProperty); }
        set { SetValue(CommandProperty, value); }
    }

    public static readonly DependencyProperty SelectedItemProperty =
        DependencyProperty.Register("SelectedItem", typeof(object), typeof(TreeViewSelectionBehavior), new UIPropertyMetadata(null, OnSelectedItemChanged));

    public static readonly DependencyProperty CommandProperty = 
        DependencyProperty.Register("Command", typeof(ICommand), typeof(TreeViewSelectionBehavior), null);

    private static void OnSelectedItemChanged(DependencyObject sender, DependencyPropertyChangedEventArgs e)
    {
        var item = e.NewValue as TreeViewItem;
        if (item != null)
        {
            item.SetValue(TreeViewItem.IsSelectedProperty, true);
        }
    }

    protected override void OnAttached()
    {
        base.OnAttached();

        this.AssociatedObject.SelectedItemChanged += OnTreeViewSelectedItemChanged;

        this.AssociatedObject.AddHandler(TreeViewItem.ExpandedEvent, new RoutedEventHandler(this.Expanded));
    }

    private void Expanded(object sender, RoutedEventArgs e)
    {
        TreeViewItem item = e.OriginalSource as TreeViewItem;

        if (this.Command.CanExecute(item))
        {
            this.Command.Execute(item);
        }
    }

    protected override void OnDetaching()
    {
        base.OnDetaching();

        if (this.AssociatedObject != null)
        {
            this.AssociatedObject.SelectedItemChanged -= OnTreeViewSelectedItemChanged;
            this.AssociatedObject.RemoveHandler(TreeViewItem.ExpandedEvent, new RoutedEventHandler(this.Expanded));
        }
    }

    private void OnTreeViewSelectedItemChanged(object sender, RoutedPropertyChangedEventArgs<object> e)
    {
        this.SelectedItem = e.NewValue;
    }
}

然后用法很简单

<i:Interaction.Behaviors>
  <local:TreeViewSelectionBehavior SelectedItem="{Binding SelectedItem}" Command="{Binding ExpandHistoricalItemCommand}"/>
</i:Interaction.Behaviors>

WPF中的扩展器控制

4 个答案: