基于所选行的WPF上下文菜单控制 [英] WPF context menu controling based on a line selected

问题描述

你好，
我有一个WPF应用程序，它显示项目列表(列表视图).
上下文菜单作为资源添加到列表视图:

Hello,
I have a WPF application which displays list of items (listview).
The context menu is added as a resource to the listview:

<listview.resources>
                <contextmenu x:key="ItemContextMenu" opened="listViewContextMenu_Opened" contextmenuopening="listViewContextMenu_ContextMenuOpening" name="listViewContextMenu" xmlns:x="#unknown">
                    <menuitem header="Rename" previewmousedown="RenameMenuItem_MouseDown" />
                    <menuitem header="Delete" previewmousedown="DeleteMenuItem_MouseDown" />
                    <menuitem header="View File" previewmousedown="ViewFileMenuItem_PreviewMouseDown" />
                </contextmenu>
            </listview.resources>

然后用于项目容器样式:

And then used in an item container style:

<listview.itemcontainerstyle>
                <Style TargetType="{x:Type ListViewItem}">
                    <eventsetter event="PreviewMouseLeftButtonDown" handler="OnListViewItem_PreviewMouseButtonDown" />
                    <setter property="ContextMenu" value="{StaticResource ItemContextMenu}" />
                </Style>
            </listview.itemcontainerstyle>

现在，问题是我想根据所选的行阻止某些上下文菜单项，即我需要分析所选的项，然后决定要显示的项.

我找不到解决方法，请帮忙！

Now, the problem is I want to prevent some context menu items based on the line selected, i.e, I need to analize the item selected and then decide which items to display.

I couldn''t find a way to do that, please help!

推荐答案

这可以通过绑定来完成.请使用以下内容:

C#-ViewModels:

Hi,

this could be accomplished with binding. Use the following:

C# - ViewModels:

public class ListViewViewModel : INotifyPropertyChanged
   {
      public event PropertyChangedEventHandler PropertyChanged;

      public List<ItemViewModel> ItemsSource
      {
         get;
         set;
      }

      public ListViewViewModel()
      {
         this.ItemsSource = new List<ItemViewModel>();
         this.ItemsSource.Add(new ItemViewModel
         {
            DisplayText = "ItemsSource #1"
         });
         this.ItemsSource.Add(new ItemViewModel
         {
            DisplayText = "ItemsSource #2"
         });
         this.ItemsSource.Add(new ItemViewModel
         {
            DisplayText = "ItemsSource #3"
         });
      }
   }

public class ItemViewModel : INotifyPropertyChanged
{
   public event PropertyChangedEventHandler PropertyChanged;

   public string DisplayText { get; set; }

   public Visibility M1Visibility {
      get {
         return (!this.DisplayText.Contains("1")) ? Visibility.Visible : Visibility.Collapsed;
      }
   }

   public Visibility M2Visibility {
      get {
         return (!this.DisplayText.Contains("2")) ? Visibility.Visible : Visibility.Collapsed;
      }
   }
}

XAML:

XAML:

<ListView
   ItemsSource="{Binding Path=ItemsSource}" DisplayMemberPath="DisplayText">
   <ListView.ItemContainerStyle>
      <Style
         TargetType="{x:Type ListViewItem}">
         <Setter
            Property="ContextMenu">
            <Setter.Value>
               <ContextMenu>
                  <MenuItem
                     Header="MenueItem #1"
                     Visibility="{Binding Path=M1Visibility}" />
                  <MenuItem
                     Header="MenueItem #2"
                     Visibility="{Binding Path=M2Visibility}" />
               </ContextMenu>
            </Setter.Value>
         </Setter>

      </Style>
   </ListView.ItemContainerStyle>

</ListView>

为了清楚起见，我对您的XAML进行了一些更改(至少这是我的意图).缺少一行代码，其中ListView容器的DataContext设置为ListViewViewModel的实例.

如果使用此功能，您将看到ListItem#1隐藏MenueItem#1，ListItem#2隐藏MenueItem#2，最后一个ListItem不隐藏MenueItem.

关键概念是ContextMenue的DataContext继承自ListViewItem.因此，这就是应用可见性逻辑的关键所在.您可以像我一样使用一些特定于上下文的逻辑，也可以使用初始化程序提供可见性值.

如果您需要进一步的帮助，请随时询问.

干杯
于尔根

-
如果这样可以节省您一些时间，请花点时间进行投票.

I''ve made a few changes to your XAML for the sake clearness (this was at least my intention). There is a line of code missing, where the DataContext of the ListView''s container is set to an instance of ListViewViewModel.

If you use this, you will see, that the ListItem #1 hides MenueItem #1, ListItem #2 hides MenueItem #2 and the last ListItem hides no MenueItem.

The key concept is, that the DataContext for the ContextMenue is inherited from the ListViewItem; so it is the point where to apply the visbility-logic. You can use some context-specific logic as I did or you can use the initialisers to provide the visibility values.

If you need further help, feel free to ask.

Cheers
Jürgen

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