如何在Xamarin.Forms地图上长按打开上下文菜单？

Hey there! I’ve tackled this exact problem in my own Xamarin.Forms map projects, so let me share two reliable ways to get that context menu popping up when you long-press the map.

Option 1: Use Xamarin.Forms' Built-in ContextMenu (XF 5.0+) #

This is the simplest approach if you’re on a newer version of Xamarin.Forms. Here’s how to set it up:

1. Add the ContextMenu to your Map in XAML
   First, define your menu options directly on the Map control:

   <maps:Map x:Name="MyMap" LongClicked="MyMap_LongClicked">
       <maps:Map.ContextMenu>
           <ContextMenu>
               <MenuItem Text="Add Marker" Clicked="AddMarker_Clicked"/>
               <MenuItem Text="View Nearby Places" Clicked="ViewNearby_Clicked"/>
               <MenuItem Text="Share Location" Clicked="ShareLocation_Clicked"/>
           </ContextMenu>
       </maps:Map.ContextMenu>
   </maps:Map>
   

2. Trigger the Menu from the Long Press Event
   In your code-behind, use the existing long press event to toggle the menu open. You’ll also want to capture the pressed position for later use (like adding a marker at that spot):

   private Position _lastLongPressedPosition;
   
   private void MyMap_LongClicked(object sender, MapLongClickedEventArgs e)
   {
       // Save the tapped geographic position for menu actions
       _lastLongPressedPosition = e.Position;
       // Open the context menu
       MyMap.ContextMenu.IsOpen = true;
   }
   
   // Example menu action: Add a marker at the pressed position
   private void AddMarker_Clicked(object sender, EventArgs e)
   {
       MyMap.Pins.Add(new Pin
       {
           Position = _lastLongPressedPosition,
           Label = "Custom Marker"
       });
   }
   

3. Disable Native Map Long Press Menus (Avoid Conflicts)
   On Android and iOS, the native map controls have their own long press menus. To prevent them from conflicting with your custom menu, add a custom renderer for each platform:

   Android Renderer

   [assembly: ExportRenderer(typeof(Map), typeof(CustomMapRenderer))]
   namespace YourAppName.Droid.Renderers
   {
       public class CustomMapRenderer : MapRenderer
       {
           public CustomMapRenderer(Context context) : base(context) { }
   
           protected override void OnElementChanged(ElementChangedEventArgs<Map> e)
           {
               base.OnElementChanged(e);
               if (Control != null)
               {
                   // Disable Android's native map long press menu
                   Control.Map.LongClickable = false;
               }
           }
       }
   }
   

   iOS Renderer

   [assembly: ExportRenderer(typeof(Map), typeof(CustomMapRenderer))]
   namespace YourAppName.iOS.Renderers
   {
       public class CustomMapRenderer : MapRenderer
       {
           protected override void OnElementChanged(ElementChangedEventArgs<Map> e)
           {
               base.OnElementChanged(e);
               if (Control is MKMapView mapView)
               {
                   // Disable iOS's native map long press recognizers
                   foreach (var recognizer in mapView.GestureRecognizers)
                   {
                       if (recognizer is UILongPressGestureRecognizer)
                       {
                           recognizer.Enabled = false;
                       }
                   }
               }
           }
       }
   }
   

Option 2: Custom Popup Menu (For Older XF or Full Customization) #

If you’re on an older version of Xamarin.Forms or need full control over the menu’s look and feel, build a custom popup:

1. Add a Popup Container to Your Page
   Use an AbsoluteLayout to overlay a custom menu on top of your map:

   <AbsoluteLayout>
       <maps:Map x:Name="MyMap" LongClicked="MyMap_LongClicked"/>
       <!-- Hidden popup menu -->
       <Frame x:Name="CustomContextMenu" 
              IsVisible="False"
              BackgroundColor="White"
              CornerRadius="8"
              Padding="12"
              AbsoluteLayout.LayoutFlags="PositionProportional">
           <StackLayout>
               <Button Text="Add Marker" Clicked="AddMarker_Clicked" Margin="0,0,0,8"/>
               <Button Text="View Nearby" Clicked="ViewNearby_Clicked" Margin="0,0,0,8"/>
               <Button Text="Share Location" Clicked="ShareLocation_Clicked"/>
           </StackLayout>
       </Frame>
   </AbsoluteLayout>
   

2. Show the Popup at the Long Press Position
   Convert the geographic position to screen coordinates and position the popup there:

   private Position _lastLongPressedPosition;
   
   private void MyMap_LongClicked(object sender, MapLongClickedEventArgs e)
   {
       _lastLongPressedPosition = e.Position;
       // Convert map position to screen coordinates
       var screenPoint = MyMap.GetScreenCoordinate(e.Position);
       // Position the popup at the tapped spot
       AbsoluteLayout.SetLayoutBounds(CustomContextMenu, 
           new Rectangle(screenPoint.X, screenPoint.Y, AbsoluteLayout.AutoSize, AbsoluteLayout.AutoSize));
       CustomContextMenu.IsVisible = true;
   }
   

3. Add Close-on-Tap Logic
   Let users close the menu by tapping anywhere else on the page:

   public YourMapPage()
   {
       InitializeComponent();
       // Add tap gesture to close the menu
       var pageTap = new TapGestureRecognizer();
       pageTap.Tapped += (s, args) => CustomContextMenu.IsVisible = false;
       Content.GestureRecognizers.Add(pageTap);
   }
   

Quick Notes #

• Always capture the long-pressed position so your menu actions have access to the exact spot the user tapped.
• Test on both Android and iOS to ensure no native menu conflicts slip through.

内容的提问来源于stack exchange，提问作者Pelin Konaray