WPF:显示 GridView 项目的上下文菜单 [英] WPF: Displaying a Context Menu for a GridView's Items
问题描述
我有以下 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>
现在我想在有界项目上单击鼠标右键显示一个上下文菜单，这将允许我在处理后面代码中的事件时检索所选项目.
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.
我可以通过什么方式实现这一点?
In what possible way can I accomplish this?
[更新]
关注丹尼斯·罗奇的代码，我现在有这个:
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>
但是在运行时，我收到此异常:
But upon running, I am receiving this exception:
无法添加类型的内容'System.Windows.Controls.ContextMenu'到System.Object"类型的对象.对象错误'System.Windows.Controls.ContextMenu'在标记文件中'MusicRepo_Importer;component/controls/trackgridcontrol.xaml'.
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'.
有什么问题?
推荐答案
是的，使用上下文菜单添加 ListView.ItemContainerStyle.
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>
注意:您需要将 ContextMenu 作为资源引用，不能在本地定义它.
NOTE: You need to reference the ContextMenu as a resource and cannot define it locally.
这将为整行启用上下文菜单.:)
This will enable the context menu for the entire row. :)
还看到我处理了 PreviewMouseLeftButtonDown 事件，因此我可以确保项目获得焦点(并且是查询 ListView 时当前选定的项目).我发现在应用程序之间改变焦点时我不得不这样做，在你的情况下这可能不是真的.
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.
更新
在代码隐藏文件中，您需要遍历可视化树以找到列表容器项目，因为事件的原始来源可以是项目模板的元素(例如堆栈面板).
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();
}
MyVisualTreeHelper 使用我编写的包装器来快速遍历可视化树.下面贴出一个子集.
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);
}
}
我希望这些附加信息有帮助.
I hope this additional information helps.
丹尼斯
这篇关于WPF:显示 GridView 项目的上下文菜单的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
