android - Take Screenshot of SurfaceView

Question

Am developing a simple camera app. I have code that takes screenshot of the whole activity and writes it to the Sd card. the problem is that the Surfaceview returns a black screen.

I would like to know how to independently take a screenshot of the surfaceview only. here is the code that takes the screenshot of the Whole activity.

    findViewById(R.id.screen).setOnClickListener(new OnClickListener() {
      @Override
     public void onClick(View v) {
     final RelativeLayout layout = (RelativeLayout) findViewById(R.id.RelativeLayout1);
      layout.setVisibility(RelativeLayout.GONE);
       Bitmap bitmap = takeScreenshot();
        Toast.makeText(getApplicationContext(),"Please Wait",         Toast.LENGTH_LONG).show();
       saveBitmap(bitmap);
   }
});

}



      public Bitmap takeScreenshot() {
       View rootView = findViewById(android.R.id.content).getRootView();
       rootView.setDrawingCacheEnabled(true);
       return rootView.getDrawingCache();
    }


           public void saveBitmap(Bitmap bitmap) {
         final MediaPlayer cheer = MediaPlayer.create(PicShot.this, R.raw.shutter);
       cheer.start();
        Random generator = new Random();
      int n = 10000;
       n = generator.nextInt(n);
        String fname = "Image-"+ n +".png";
      final RelativeLayout layout = (RelativeLayout)     findViewById(R.id.RelativeLayout1);
     File imagePath = new File(Environment.getExternalStorageDirectory() + "/" + fname);
     FileOutputStream fos;
      try {
        fos = new FileOutputStream(imagePath);
        bitmap.compress(CompressFormat.PNG, 100, fos);
        fos.flush();
        fos.close();
        layout.setVisibility(RelativeLayout.VISIBLE);
        Intent share = new Intent(Intent.ACTION_SEND);
        share.setType("image/*");
        Uri uri = Uri.fromFile(imagePath);
        share.putExtra(Intent.EXTRA_STREAM,uri);
        startActivity(Intent.createChooser(share, "Share Image"));
    } catch (FileNotFoundException e) {
        Log.e("GREC", e.getMessage(), e);
    } catch (IOException e) {
        Log.e("GREC", e.getMessage(), e);
    }
}

Answer 1

The SurfaceView's surface is independent of the surface on which View elements are drawn. So capturing the View contents won't include the SurfaceView.

You need to capture the SurfaceView contents separately and perform your own composition step. The easiest way to do the capture is probably to just re-render the contents, but use an off-screen bitmap as the target rather than the surface. If you're rendering with GLES to an off-screen pbuffer, you can use glReadPixels() before you swap buffers.

Update: Grafika's "texture from camera" activity demonstrates handling live video from the camera with OpenGL ES. EglSurfaceBase#saveFrame() shows how to capture GLES rendering to a Bitmap.

Update: See also this answer, which provides a bit more background.