将 DataGrid 行中的 DoubleClick 命令绑定到 VM

Question

我有一个 Datagrid，不喜欢我的解决方法，即在我的视图模型上为单击（又名选定）行触发双击命令。

查看：

   <DataGrid  EnableRowVirtualization="True"
              ItemsSource="{Binding SearchItems}"
              SelectedItem="{Binding SelectedItem}"
              SelectionMode="Single"
              SelectionUnit="FullRow">

        <i:Interaction.Triggers>
            <i:EventTrigger EventName="MouseDoubleClick">
                <cmd:EventToCommand Command="{Binding MouseDoubleClickCommand}" PassEventArgsToCommand="True" />
            </i:EventTrigger>
        </i:Interaction.Triggers>
        ...
  </DataGrid>

视图模型：

    public ICommand MouseDoubleClickCommand
    {
        get
        {
            if (mouseDoubleClickCommand == null)
            {
                mouseDoubleClickCommand = new RelayCommand<MouseButtonEventArgs>(
                    args =>
                    {
                        var sender = args.OriginalSource as DependencyObject;
                        if (sender == null)
                        {
                            return;
                        }
                        var ancestor = VisualTreeHelpers.FindAncestor<DataGridRow>(sender);
                        if (ancestor != null)
                        {
                            MessengerInstance.Send(new FindDetailsMessage(this, SelectedItem.Name, false));
                        }
                    }
                    );
            }
            return mouseDoubleClickCommand;
        }
    }

我想在我的视图模型中摆脱与视图相关的代码（具有依赖对象和可视化树助手的代码），因为这会以某种方式破坏可测试性。但另一方面，这样我可以避免当用户没有点击行而是点击标题时发生某些事情。

PS：我尝试查看附加行为，但无法在工作时从 Skydrive 下载，因此最好使用“内置”解决方案。

Answer 1

你可以试试这个解决方法：

<DataGrid  EnableRowVirtualization="True"
          ItemsSource="{Binding SearchItems}"
          SelectedItem="{Binding SelectedItem}"
          SelectionMode="Single"
          SelectionUnit="FullRow">
    <DataGrid.Columns>
        <DataGridTemplateColumn Header=".....">
            <DataGridTemplateColumn.CellTemplate>
                <DataTemplate>
                        <TextBlock .....>
                            <i:Interaction.Triggers>
                                <i:EventTrigger EventName="MouseDoubleClick">
                                    <cmd:EventToCommand Command="{Binding MouseDoubleClickCommand}" PassEventArgsToCommand="True" />
                                </i:EventTrigger>
                            </i:Interaction.Triggers>
                        </TextBlock>
                </DataTemplate>
    ...................

在这种情况下，您必须为DataGrid 中的每一列指定DataTemplate

Answer 2

以下是使用附加行为实现它的方法：

编辑：现在在 DataGridRow 而不是 DataGrid 上注册行为，以便忽略 DataGridHeader 的点击。

行为：

public class Behaviours
{
    public static DependencyProperty DoubleClickCommandProperty =
       DependencyProperty.RegisterAttached("DoubleClickCommand", typeof(ICommand), typeof(Behaviours),
                                           new PropertyMetadata(DoubleClick_PropertyChanged));

    public static void SetDoubleClickCommand(UIElement element, ICommand value)
    {
        element.SetValue(DoubleClickCommandProperty, value);
    }

    public static ICommand GetDoubleClickCommand(UIElement element)
    {
        return (ICommand)element.GetValue(DoubleClickCommandProperty);
    }

    private static void DoubleClick_PropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        var row = d as DataGridRow;
        if (row == null) return;

        if (e.NewValue != null)
        {
            row.AddHandler(DataGridRow.MouseDoubleClickEvent, new RoutedEventHandler(DataGrid_MouseDoubleClick));
        }
        else
        {
            row.RemoveHandler(DataGridRow.MouseDoubleClickEvent, new RoutedEventHandler(DataGrid_MouseDoubleClick));
        }
    }

    private static void DataGrid_MouseDoubleClick(object sender, RoutedEventArgs e)
    {
        var row= sender as DataGridRow;

        if (row!= null)
        {
            var cmd = GetDoubleClickCommand(row);
            if (cmd.CanExecute(row.Item))
                cmd.Execute(row.Item);
        }
    }
}

Xaml：

    <DataGrid x:Name="grid" EnableRowVirtualization="True"
          SelectedItem="{Binding SelectedItem}"
          SelectionMode="Single"
          SelectionUnit="FullRow" ItemsSource="{Binding SearchItems}">
       <DataGrid.RowStyle>
           <Style TargetType="DataGridRow">
                <Setter Property="Behaviours.DoubleClickCommand" Value="{Binding ElementName=grid, Path=DataContext.SortStateCommand}"/>
           </Style>
       </DataGrid.RowStyle>

然后您需要修改您的 MouseDoubleClickCommand 以删除 MouseButtonEventArgs 参数并将其替换为您的 SelectedItem 类型。

Answer 3

您为什么不直接使用CommandParameter？

<DataGrid x:Name="myGrd"
          ItemsSource="{Binding SearchItems}"
          SelectedItem="{Binding SelectedItem}"
          SelectionMode="Single"
          SelectionUnit="FullRow">

    <i:Interaction.Triggers>
        <i:EventTrigger EventName="MouseDoubleClick">
            <cmd:EventToCommand Command="{Binding MouseDoubleClickCommand}"  
                                CommandParameter="{Binding ElementName=myGrd, Path=SelectedItem}" />
        </i:EventTrigger>
    </i:Interaction.Triggers>
    ...
</DataGrid>

你的命令是这样的：

public ICommand MouseDoubleClickCommand
{
    get
    {
        if (mouseDoubleClickCommand == null)
        {
            mouseDoubleClickCommand = new RelayCommand<SearchItem>(
                item =>
                {
                    var selectedItem = item;
                });
        }

        return mouseDoubleClickCommand;
    }
}

编辑：我现在用这个代替Interaction.Triggers：

<DataGrid.InputBindings>
    <MouseBinding MouseAction="LeftDoubleClick"
                  Command="{Binding Path=MouseDoubleClickCommand}"
                  CommandParameter="{Binding ElementName=myGrd, Path=SelectedItem}" />
</DataGrid.InputBindings>

Answer 4

比这里提出的任何解决方案都简单。

我正在使用这个。

<!-- 
requires IsSynchronizedWithCurrentItem
for more info on virtualization/perf https://stackoverflow.com/questions/9949358/datagrid-row-virtualization-display-issue 
 -->
        <DataGrid ItemsSource="{Binding SearchItems}" 
                  IsSynchronizedWithCurrentItem="True"
                  AutoGenerateColumns="false" CanUserAddRows="False" CanUserDeleteRows="False" IsReadOnly="True" EnableRowVirtualization="True"
                  >

            <!-- for details on ICollection view (the magic behind {Binding Accounts/} https://marlongrech.wordpress.com/2008/11/22/icollectionview-explained/ -->

            <DataGrid.InputBindings>
                <MouseBinding
                    MouseAction="LeftDoubleClick"
                    Command="{Binding MouseDoubleClickCommand}"
                    CommandParameter="{Binding SearchItems/}" />
            </DataGrid.InputBindings>
        </DataGrid>

来自WPF DataGrid: CommandBinding to a double click instead of using Events