Too much work on main thread Warning

Question

I developed a very basic camera app, so far it only contains the camera preview and a button to take a photo which is then saved. I am now wondering why I would run into a warning that my application might be doing to much work on it's main thread (it skips 35 frames). All I do so far on my UI thread can be seen in my onCreate():

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    fullScreencall();

    setContentView(R.layout.activity_capture);

    mCamera = getCameraInstance();

    // Create our Preview view and set it as the content of our activity.
    mPreview = new CameraPreview(this, mCamera);
    FrameLayout preview = (FrameLayout) findViewById(R.id.camera);
    preview.addView(mPreview, 0);
    mButtonCapture = (Button) findViewById(R.id.btnCapturePhoto);
    mButtonCapture.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            ImageSaverThread ist = new ImageSaverThread(mCamera);
            ist.start();
        }
    });
}

To me, this seems not to be so much work, and I cannot find anything that I could separate into another thread. Taking a photo and saving it is already done in a thread.

Any idea what I am missing here?

EDIT

ImageSaverThread.java

public class ImageSaverThread extends Thread {

    private Camera mCamera;
    public static final int MEDIA_TYPE_IMAGE = 1;

    public ImageSaverThread(Camera camera){
        mCamera = camera;
    }

    public void run(){
        PictureCallback mPicture = new PictureCallback() {

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

                File pictureFile = getOutputMediaFile(MEDIA_TYPE_IMAGE);
                if (pictureFile == null){
                    return;
                }

                try {
                    FileOutputStream fos = new FileOutputStream(pictureFile);
                    fos.write(data);
                    fos.flush();
                    fos.close();
                } catch (FileNotFoundException e) {
                    Log.d("FAIL", "File not found: " + e.getMessage());
                } catch (IOException e) {
                    Log.d("FAIL", "Error accessing file: " + e.getMessage());
                }
            }
        };
        mCamera.takePicture(null, null, mPicture);
    }

    private static File getOutputMediaFile(int type){
        // To be safe, you should check that the SDCard is mounted
        // using Environment.getExternalStorageState() before doing this.

        File mediaStorageDir = new File(String.valueOf(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS)));
        // This location works best if you want the created images to be shared
        // between applications and persist after your app has been uninstalled.

        // Create the storage directory if it does not exist
        if (! mediaStorageDir.exists()){
            if (! mediaStorageDir.mkdirs()){
                Log.d("MyCameraApp", "failed to create directory");
                return null;
            }
        }
        String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
        File mediaFile;
        if (type == MEDIA_TYPE_IMAGE){
            mediaFile = new File(mediaStorageDir.getPath() + File.separator +
                    "IMG_"+ timeStamp + ".jpg");
        } else {
            return null;
        }

        return mediaFile;
    }
}

Your `ImageSaverThread` class, mind posting the code for it? — asadmshah, Dec 09 '15 at 17:14

score 1 · Answer 1 · edited May 23 '17 at 12:30

1

getCameraInstance can be a long running process. You may need to run it on another thread. The documentation suggests doing that.

See the answer posted here for more about that: Android camera: Threads? Which should do what

EDIT:

When someone clicks on the button, you might have a different issue. Your static method is not created until the ImageSaverThread object is instantiated. Checking for the file, etc. might take some time as a static method, so you may want to change that to a non-static method.

For more, see this post. Static Initialization Blocks

Also, this is a "warning" - not an "error". 35 frames is not much, and the frame count will vary depending on available memory, platform and other priority threads that might be running.

edited May 23 '17 at 12:30

Community

1
1

answered Dec 09 '15 at 17:25

Jim

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does this also explain why i only get this error when i click the button for taking a picture? – PKlumpp Dec 09 '15 at 17:46
that's probably different. I edited my response, I hope it helps. – Jim Dec 09 '15 at 18:20

Too much work on main thread Warning

1 Answers1