Question

I experienced 2 strange thing when I pressed the shutter button on my CameraActivity

1. On device 2.3 and 4.0 (Galaxy Ace II, Nexus One and Galaxy Nexus),
   it will freeze for about 2 seconds then proceed to nextActivity.

2. Only Galaxy Ace 2.3.6, it will give me a garbled pixels like the pic
   below during the freezing period of time, but it can give me the correct image later in nextActivity.

At first I thought something might be wrong or time consuming in my PicutureCallback method, but it seems ok? And I can’t understand why this garbled pixels will show up only on Galaxy Ace.

So will there be a better way to handle the PictureCallback to make it quicker?

There’s no error log, so I just put my related code:

// I call the takePicture in my button listener.
camera.takePicture(null, null, mPicture);

// here's the picture callback
private PictureCallback mPicture = new PictureCallback() {

    @Override
    public void onPictureTaken(byte[] data, Camera camera) {


        new ShutterHandler(data).execute();
    }

    class ShutterHandler extends AsyncTask<Void, Void, Void> {

        Bitmap bm;
        String timeStamp;
        String filename;
        Intent nextIntent = new Intent(CameraActivity.this, nextActivity.class);

        // a tricky way to pass data into the AsyncTask
        public ShutterHandler(byte[] data) {
            bm = BitmapFactory.decodeByteArray(data, 0, data.length);

        }


        @Override
        protected Void doInBackground(Void... params) {
            // simply generate a time stamp as filename
            timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
            filename = timeStamp + ".jpg";
            Uri path;
            try {

                // save file to app's private folder
                FileOutputStream fos = openFileOutput(filename, Context.MODE_PRIVATE);

                bm.compress(Bitmap.CompressFormat.JPEG, 100, fos);              
                // retrieve Uri from the file
                path = Uri.fromFile(getFileStreamPath(filename));

                Log.d("CameraActivity", "file saved to: " + path);
                fos.flush();
                fos.close();

                // launch ShowMarkersActivity
                String pathString = path.getPath();
                nextIntent.putExtra("IMG", pathString);
                nextIntent.putExtra("FileName", filename);
                nextIntent.putExtra("FLAG", true);

            } catch (FileNotFoundException e) {
                Log.d("CameraActivity", "File not found: " + e.getMessage());
            } catch (IOException e) {
                Log.d("CameraActivity", "Error accessing file: " + e.getMessage());
            }
            return null;                        
        }
        protected void onPostExecute(Void v) {
            CameraActivity.this.startActivity(nextIntent);
            finish();
        }

    }
};

Answer 1

If you ask the camera picture callback to return jpeg format, it will all be significantly faster. Still the picture callback is slow on most of the available devices.