title: How to get the current frame (as a Bitmap) for android facedetector in a Tracker event?
body: <p>I have the standard com.google.android.gms.vision.Tracker <a href="https://github.com/googlesamples/android-vision/blob/master/visionSamples/FaceTracker/app/src/main/java/com/google/android/gms/samples/vision/face/facetracker/FaceTrackerActivity.java" rel="noreferrer">example</a> successfully running on my android device and now i need to postprocess the image to find the iris of the current face which has been notified in the event methods of the Tracker.</p>
  
  <p>So, how do i get the Bitmap frame which matches exactly the com.google.android.gms.vision.face.Face i received in the Tracker events?
  This also means that the final bitmap should match the webcam resolution and not the screen resolution.</p>
  
  <p>One bad alternative solution is to call takePicture every few ms on my CameraSource and process this picture separately using the FaceDetector. Although this works i have the problem that the video stream freezes during takepicture and i get lots of GC_FOR_ALLOC messages cause of the single bmp facedetector memory waste.</p>