Camera preview freezes after screen lock

Question

The custom camera app I've written stops giving the preview after the screen locks (by pushing lock butten or waiting for a couple of minutes). I don't get an exception, which makes it quite difficult to find the problem.

Does the android screen lock (if that's the correct term) pauses/halts/... my App (activity)?

If this were the case, could the cause be my onPause/onResume methods? Or is another cause mor likely?

Thanks in advance

Answer 1

I faced same problem and fixed it using following steps:

1. I created my camera preview and added it to the container FrameLayout in onResume() of the parent activity. Something like:

   public void onResume{
       super.onResume();
       mCamera = Camera.open();
       if(null != mCamera){
           mCamera.setDisplayOrientation(90);
           mPreview = new CameraOverlay(getActivity(), mCamera);
           frLyParent.addView(mPreview);
       }
   }
   

2. I removed the view in onPause(). This fixes the freeze.

   public void onPause(){
       super.onPause();
       if(null != mCamera){
           mCamera.release();
           mCamera = null;
       }
       frLyParent.removeView(mPreview);
       mPreview = null;
   }
   

where CameraOverlay() is the class which extends SurfaceView and implements SurfaceHolder.Callback. Do let me know if you need that implementation.

Answer 2

here is mine, it does work :-)

@Override
    public void onResume() {
        super.onResume();
        try {
            camera = Camera.open();
            holder.addCallback(this);
            surface.setVisibility(View.VISIBLE);
        } catch (Exception e) {
            e.printStackTrace();
        }

    }

    @Override
    public void onPause() {
        try {
            surface.setVisibility(View.GONE);
            holder.removeCallback(this);
            camera.release();
        } catch (Exception e) {
            e.printStackTrace();
        }
        super.onPause();
    }

Answer 3

In onResume() method add this line :

surfaceView.setVisibility(View.VISIBLE);

In onPaused() method add this line :

surfaceView.setVisibility(View.GONE);