Answers

• AliaksandrSheliutsin USMember ✭

  May 2016 edited May 2016

  Done! Was helped on stackoverflow, but there is a question: why we need NSAutoreleasePool?

  [DllImport("/System/Library/Frameworks/ApplicationServices.framework/Versions/A/Frameworks/CoreGraphics.framework/CoreGraphics")]
  private static extern IntPtr CGWindowListCreateImage(RectangleF screenBounds, CGWindowListOption windowOption, uint windowID, GWindowImageOption imageOption);
  
  partial void ButtonClicked (Foundation.NSObject sender) {
  
      using (var pool = new NSAutoreleasePool())
      {
          CGRect fullScreenBounds = NSScreen.MainScreen.Frame;
          IntPtr imageRef = CGWindowListCreateImage((RectangleF)fullScreenBounds, CGWindowListOption.All, 0, CGWindowImageOption.Default);
          var cgImage = new CGImage(imageRef);
          var filePath = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.Desktop), "StackOverflow.png");
          var fileURL = new NSUrl(filePath, false);
          var imageDestination = CGImageDestination.Create(fileURL, UTType.PNG, 1);
          imageDestination.AddImage(cgImage);
          imageDestination.Close();
      }
  }
  

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• ChrisHamons USForum Administrator, Xamarin Team Xamurai

  May 2016

  So the auto release pool is primarily just a way to scope the memory allocations if a bunch are created in a short period of time that you want cleaned up.

  If your application creates a lot of temporary autoreleased objects within the event loop, however, it may be beneficial to create “local” autorelease pools to help to minimize the peak memory footprint.

  https://developer.apple.com/library/mac/documentation/Cocoa/Reference/Foundation/Classes/NSAutoreleasePool_Class/

  1
• bogdanvi86 Member ✭

  July 2018

  Hi Chris,
  For the code above to work I had to use a CGRect instead of a RectangleF in the definition of CGWindowListCreateImage. Beside that, this does not seem to free the memory. I run this in a loop 40 times just to confirm and the memory usage is huge.
  Any suggestions as to how I can avoid this leak?

  Thanks.
  Bogdan

  PS: thanks for all useful answers you post in the forum!

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• ChrisHamons USForum Administrator, Xamarin Team Xamurai

  July 2018

  This thread was from 2016 and in Classic, not unified, so CGRect was RectangleF back then.

  You very likely need to CFRelease your handle from CGWindowListCreateImage when you are finished. When you manually bind APIs, it is your responsibility to handle memory management. C# knows nothing of the memory that was allocated on your behalf.

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