c# - WPF: Displaying a Context Menu for a GridView's Items

Question

I have the following GridView:

<ListView Name="TrackListView" ItemContainerStyle="{StaticResource itemstyle}">
    <ListView.View>
        <GridView>
            <GridViewColumn Header="Title" Width="100" HeaderTemplate="{StaticResource BlueHeader}" DisplayMemberBinding="{Binding Name}"/>
            <GridViewColumn Header="Artist" Width="100" HeaderTemplate="{StaticResource BlueHeader}" DisplayMemberBinding="{Binding Album.Artist.Name}" />
            <GridViewColumn Header="Album" Width="100" HeaderTemplate="{StaticResource BlueHeader}" DisplayMemberBinding="{Binding Album.Name}"/>
            <GridViewColumn Header="Length" Width="100" HeaderTemplate="{StaticResource BlueHeader}"/>
        </GridView>
     </ListView.View>
</ListView>

Now I would like to display a context menu on a right click on a bounded item that will allow me to retrieve the item selected when I handle the event in the code behind.

In what possible way can I accomplish this?

---

[Update]

Following Dennis Roche's code, I now have this:

    <ListView Name="TrackListView" ItemContainerStyle="{StaticResource itemstyle}">
        <ListView.ItemContainerStyle>
            <Style TargetType="{x:Type ListViewItem}">
                <EventSetter Event="PreviewMouseLeftButtonDown" Handler="OnListViewItem_PreviewMouseLeftButtonDown" />
                <Setter Property="ContextMenu">
                    <Setter.Value>
                        <ContextMenu>
                            <MenuItem Header="Add to Playlist"></MenuItem>
                        </ContextMenu>
                     </Setter.Value>
                </Setter>
            </Style>
        </ListView.ItemContainerStyle>

        <ListView.View>
            <GridView>
                <GridViewColumn Header="Title" Width="100" HeaderTemplate="{StaticResource BlueHeader}" DisplayMemberBinding="{Binding Name}"/>
                <GridViewColumn Header="Artist" Width="100" HeaderTemplate="{StaticResource BlueHeader}" DisplayMemberBinding="{Binding Album.Artist.Name}" />
                <GridViewColumn Header="Album" Width="100" HeaderTemplate="{StaticResource BlueHeader}" DisplayMemberBinding="{Binding Album.Name}"/>
                <GridViewColumn Header="Length" Width="100" HeaderTemplate="{StaticResource BlueHeader}"/>
            </GridView>
         </ListView.View>
    </ListView>

But upon running, I am receiving this exception:

Cannot add content of type 'System.Windows.Controls.ContextMenu' to an object of type 'System.Object'. Error at object 'System.Windows.Controls.ContextMenu' in markup file 'MusicRepo_Importer;component/controls/trackgridcontrol.xaml'.

What is the problem?

Answer 1

Yes, add a ListView.ItemContainerStyle with the Context Menu.

<ListView>
  <ListView.Resources>
    <ContextMenu x:Key="ItemContextMenu">
      ...
    </ContextMenu>
  </ListView.Resources>
  <ListView.ItemContainerStyle>
    <Style TargetType="{x:Type ListViewItem}">
      <EventSetter Event="PreviewMouseLeftButtonDown" Handler="OnListViewItem_PreviewMouseLeftButtonDown" />
      <Setter Property="ContextMenu" Value="{StaticResource ItemContextMenu}"/>
    </Style>
  </ListView.ItemContainerStyle>
</ListView>

NOTE: You need to reference the ContextMenu as a resource and cannot define it locally.

This will enable the context menu for the entire row. :)

Also see that I handle the PreviewMouseLeftButtonDown event so I can ensure the item is focused (and is the currently selected item when you query the ListView). I found that I had to this when changing focus between applications, this may not be true in your case.

Updated

In the code behind file you need to walk-up the visual tree to find the list container item as the original source of the event can be an element of the item template (e.g. a stackpanel).

void OnListViewItem_PreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
  if (e.Handled)
    return;

  ListViewItem item = MyVisualTreeHelper.FindParent<ListViewItem>((DependencyObject)e.OriginalSource);
  if (item == null)
    return;

  if (item.Focusable && !item.IsFocused)
    item.Focus();
}

The MyVisualTreeHelper that is use a wrapper that I've written to quickly walk the visual tree. A subset is posted below.

public static class MyVisualTreeHelper
{
  static bool AlwaysTrue<T>(T obj) { return true; }

  /// <summary>
  /// Finds a parent of a given item on the visual tree. If the element is a ContentElement or FrameworkElement 
  /// it will use the logical tree to jump the gap.
  /// If not matching item can be found, a null reference is returned.
  /// </summary>
  /// <typeparam name="T">The type of the element to be found</typeparam>
  /// <param name="child">A direct or indirect child of the wanted item.</param>
  /// <returns>The first parent item that matches the submitted type parameter. If not matching item can be found, a null reference is returned.</returns>
  public static T FindParent<T>(DependencyObject child) where T : DependencyObject
  {
    return FindParent<T>(child, AlwaysTrue<T>);
  }

  public static T FindParent<T>(DependencyObject child, Predicate<T> predicate) where T : DependencyObject
  {
    DependencyObject parent = GetParent(child);
    if (parent == null)
      return null;

    // check if the parent matches the type and predicate we're looking for
    if ((parent is T) && (predicate((T)parent)))
      return parent as T;
    else
      return FindParent<T>(parent);
  }

  static DependencyObject GetParent(DependencyObject child)
  {
    DependencyObject parent = null;
    if (child is Visual || child is Visual3D)
      parent = VisualTreeHelper.GetParent(child);

    // if fails to find a parent via the visual tree, try to logical tree.
    return parent ?? LogicalTreeHelper.GetParent(child);
  }
}

I hope this additional information helps.

Dennis