Answers

• LandLu Member, Xamarin Team Xamurai

  October 2019

  this.Window.SetFlags(WindowManagerFlags.Secure, WindowManagerFlags.Secure);
  

  This will only affect the current activity. If you move to another activity you can take screenshots there.
  I tested it on my real physical phone and place it in the OnCreate like:

  protected override void OnCreate(Bundle savedInstanceState)
  {
      base.OnCreate(savedInstanceState);
  
      Window.SetFlags(WindowManagerFlags.Secure, WindowManagerFlags.Secure);
  
      // Create your application here
      SetContentView(Resource.Layout.activity_main);
  
      // ...
  }
  

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• DannyPham USMember ✭✭✭

  October 2019

  @LandLu thanks for your answer. However, I'm using Xamarin Forms, and can't specify which activity that needs to be modified. If I put that code into MainActivity.cs, then the whole app will be affected.

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• LandLu Member, Xamarin Team Xamurai

  October 2019

  Forms only has one activity so if you do this configuration in the MainActivity all the pages can't be captured.
  You can subscribe a MessagingCenter in the OnCreate event of the main activity. When the page displays send a signal to notify the activity to disable the screenshot capturing. And enable it when it disappears.
  Here is the code:

  // Subscribe in the activity
  protected override void OnCreate(Bundle savedInstanceState)
  {
      TabLayoutResource = Resource.Layout.Tabbar;
      ToolbarResource = Resource.Layout.Toolbar;
  
      base.OnCreate(savedInstanceState);
  
      Xamarin.Essentials.Platform.Init(this, savedInstanceState);
      global::Xamarin.Forms.Forms.Init(this, savedInstanceState);
      LoadApplication(new App());
  
      MessagingCenter.Subscribe<object, bool>(this, "LockScreenshot", (sender, shouldLock) =>
      {
          if (shouldLock)
          {
              Window.SetFlags(WindowManagerFlags.Secure, WindowManagerFlags.Secure);
          }
          else
          {
              Window.ClearFlags(WindowManagerFlags.Secure);
          }
      });
  }
  
  // Send messages on a particular page
  protected override void OnAppearing()
  {
      base.OnAppearing();
  
      MessagingCenter.Send<object, bool>(this, "LockScreenshot", true);
  }
  
  protected override void OnDisappearing()
  {
      base.OnDisappearing();
  
      MessagingCenter.Send<object, bool>(this, "LockScreenshot", false);
  }
  

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