Abstract camera fragment implementation using focus modes

AbstractCameraFragment

public abstract class AbstractCameraFragment extends MDFragment implements UnexpectedTerminationHelper.OnCrashListener, SurfaceHolder.Callback, Camera.AutoFocusCallback {

    protected Camera camera;
    private boolean previewRunning, cameraReleased, focusAreaSupported, meteringAreaSupported;
    private UnexpectedTerminationHelper terminationHelper;
    private int focusAreaSize;
    private FocusSound focusSound;
    private Matrix matrix;

    protected ResultListener resultListener;

    @Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);
        resultListener = Utils.as(activity, ResultListener.class);
        if (resultListener == null) {
            throw new IllegalArgumentException("Attaching activity must implement ResultListener");
        }
    }

    @Override
    public void onCreate(Bundle sSavedInstanceState) {
        super.onCreate(sSavedInstanceState);
        terminationHelper = new UnexpectedTerminationHelper(this);
        focusAreaSize = getResources().getDimensionPixelSize(R.dimen.camera_focus_area_size);
        matrix = new Matrix();
        focusSound = new FocusSound();
    }

    @Override
    public void onAutoFocus(boolean focused, Camera camera) {
        //play default system sound if exists
        if (focused) {
            focusSound.play();
        }
    }

    @Override
    public void surfaceCreated(final SurfaceHolder holder) {
        getSurfaceView().post(() -> openCamera(holder));
    }

    private void openCamera(SurfaceHolder holder) {
        try {
            camera = Camera.open();
        } catch (Exception e) {
            Log.e(e);
        }

        if (camera != null) {
            cameraReleased = false;

            try {
                camera.setPreviewDisplay(holder);
            } catch (Exception e) {
                Log.e(e);
            }
        }

        onCameraOpened();
    }

    /**
     * On each tap event we will calculate focus area and metering area.
     * <p>
     * Metering area is slightly larger as it should contain more info for exposure calculation.
     * As it is very easy to over/under expose
     */
    protected void focusOnTouch(MotionEvent event) {
        if (camera != null) {
            //cancel previous actions
            camera.cancelAutoFocus();
            Rect focusRect = calculateTapArea(event.getX(), event.getY(), 1f);
            Rect meteringRect = calculateTapArea(event.getX(), event.getY(), 1.5f);

            Camera.Parameters parameters = null;
            try {
                parameters = camera.getParameters();
            } catch (Exception e) {
                Log.e(e);
            }

            // check if parameters are set (handle RuntimeException: getParameters failed (empty parameters))
            if (parameters != null) {
                parameters.setFocusMode(Camera.Parameters.FOCUS_MODE_AUTO);
                parameters.setFocusAreas(Collections.newArrayList(new Camera.Area(focusRect, 1000)));

                if (meteringAreaSupported) {
                    parameters.setMeteringAreas(Collections.newArrayList(new Camera.Area(meteringRect, 1000)));
                }

                try {
                    camera.setParameters(parameters);
                    camera.autoFocus(this);
                } catch (Exception e) {
                    Log.e(e);
                }
            }
        }
    }

    /**
     * Convert touch position x:y to {@link Camera.Area} position -1000:-1000 to 1000:1000.
     * <p>
     * Rotate, scale and translate touch rectangle using matrix configured in
     * {@link SurfaceHolder.Callback#surfaceChanged(android.view.SurfaceHolder, int, int, int)}
     */
    private Rect calculateTapArea(float x, float y, float coefficient) {
        int areaSize = Float.valueOf(focusAreaSize * coefficient).intValue();

        int left = clamp((int) x - areaSize / 2, 0, getSurfaceView().getWidth() - areaSize);
        int top = clamp((int) y - areaSize / 2, 0, getSurfaceView().getHeight() - areaSize);

        RectF rectF = new RectF(left, top, left + areaSize, top + areaSize);
        matrix.mapRect(rectF);

        return new Rect(Math.round(rectF.left), Math.round(rectF.top), Math.round(rectF.right), Math.round(rectF.bottom));
    }

    private int clamp(int x, int min, int max) {
        if (x > max) {
            return max;
        }
        if (x < min) {
            return min;
        }
        return x;
    }

    abstract protected void onCameraOpened();

    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
        getSurfaceView().post(() -> startPreview(holder, width, height));
    }

    private void startPreview(SurfaceHolder holder, int width, int height) {
        if (camera == null) {
            openCamera(holder);
            if (camera == null) {
                return;
            }
        }

        if (previewRunning) {
            camera.stopPreview();
            previewRunning = false;
        }

        Camera.Parameters p = null;
        try {
            p = camera.getParameters();
        } catch (Exception e) {
            Log.e(e);
        }

        // can't get camera params probably called after release
        if (p == null) {
            return;
        }

        p.setSceneMode(Camera.Parameters.SCENE_MODE_AUTO);
        p.setPictureFormat(ImageFormat.JPEG);
        p.setJpegQuality(GraphicsHelper.DEFAULT_COMPRESSION);
        Camera.Size optimalPreviewSize = getOptimalPreviewSize(p.getSupportedPreviewSizes(), width, height);
        Camera.Size optimalPictureSize = getOptimalPreviewSize(p.getSupportedPictureSizes(), width, height);

        if (optimalPreviewSize != null) {
            p.setPreviewSize(optimalPreviewSize.width, optimalPreviewSize.height);
        }

        if (optimalPictureSize != null) {
            p.setPictureSize(optimalPictureSize.width, optimalPictureSize.height);
        }

        int rotation = getActivity().getWindowManager().getDefaultDisplay().getRotation();
        int degrees = 0;
        switch (rotation) {
            case Surface.ROTATION_0:
                degrees = 0;
                break;
            case Surface.ROTATION_90:
                degrees = 90;
                break;
            case Surface.ROTATION_180:
                degrees = 180;
                break;
            case Surface.ROTATION_270:
                degrees = 270;
                break;
        }

        int orientation = 0;
        Camera.CameraInfo info = new Camera.CameraInfo();
        getCameraInfo(0, info);
        if (info.facing == Camera.CameraInfo.CAMERA_FACING_FRONT) {
            orientation = (info.orientation + degrees) % 360;
            orientation = (360 - orientation) % 360;  // compensate the mirror
        } else {  // back-facing
            orientation = (info.orientation - degrees + 360) % 360;
        }
        camera.setDisplayOrientation(orientation);

        List<String> supportedFocusModes = p.getSupportedFocusModes();

        if (supportedFocusModes.contains(FOCUS_MODE_CONTINUOUS_PICTURE)) {
            p.setFocusMode(FOCUS_MODE_CONTINUOUS_PICTURE);
        } else if (supportedFocusModes.contains(FOCUS_MODE_CONTINUOUS_VIDEO)) {
            p.setFocusMode(FOCUS_MODE_CONTINUOUS_VIDEO);
        }

        List<String> supportedFlashModes = p.getSupportedFlashModes();
        if (supportedFlashModes != null && supportedFlashModes.contains(FLASH_MODE_AUTO)) {
            p.setFlashMode(FLASH_MODE_AUTO);
        }

        if (p.getMaxNumFocusAreas() > 0) {
            this.focusAreaSupported = true;
        }

        if (p.getMaxNumMeteringAreas() > 0) {
            this.meteringAreaSupported = true;
        }

        Matrix matrix = new Matrix();
        matrix.postRotate(orientation);
        matrix.postScale(width / 2000f, height / 2000f);
        matrix.postTranslate(width / 2f, height / 2f);
        matrix.invert(this.matrix);
    }

    /**
     * Calculates and returns optimal preview size from supported by each device.
     */
    private Camera.Size getOptimalPreviewSize(List<Camera.Size> sizes, int width, int height) {
        Camera.Size optimalSize = null;

        for (Camera.Size size : sizes) {
            if ((size.width <= width && size.height <= height) || (size.height <= width && size.width <= height)) {
                if (optimalSize == null) {
                    optimalSize = size;
                } else {
                    int resultArea = optimalSize.width * optimalSize.height;
                    int newArea = size.width * size.height;

                    if (newArea > resultArea) {
                        optimalSize = size;
                    }
                }
            }
        }

        return optimalSize;
    }

    public boolean isFocusAreaSupported() {
        return focusAreaSupported;
    }

    public int getFocusAreaSize() {
        return focusAreaSize;
    }

    protected abstract CameraPreviewSurfaceView getSurfaceView();

    @Override
    public void surfaceDestroyed(SurfaceHolder surfaceHolder) {
        releaseCamera();
    }

    @Override
    public void onPause() {
        super.onPause();
        if (terminationHelper != null) {
            terminationHelper.finish();
        }
    }

    @Override
    public void onResume() {
        super.onResume();
        if (terminationHelper != null) {
            terminationHelper.start();
        }
    }

    @Override
    public void onDestroyView() {
        super.onDestroyView();
        releaseCamera();
    }

    private void releaseCamera() {
        if (camera != null) {
            try {
                if (!cameraReleased) {
                    camera.stopPreview();
                    previewRunning = false;
                    camera.release();
                    cameraReleased = true;
                    camera = null;
                }
            } catch (Exception e) {
                Log.e("Failed to release android.Camera", e);
            }
        }
    }

    @Override
    public void lastBreath(Throwable ex) {
        releaseCamera();
    }

    public void resumeContinuousAutofocus() {
        if (camera != null && focusAreaSupported) {
            camera.cancelAutoFocus();

            Camera.Parameters parameters = camera.getParameters();
            parameters.setFocusAreas(null);

            List<String> supportedFocusModes = parameters.getSupportedFocusModes();

            String focusMode = null;
            if (supportedFocusModes.contains(FOCUS_MODE_CONTINUOUS_PICTURE)) {
                focusMode = FOCUS_MODE_CONTINUOUS_PICTURE;
            } else if (supportedFocusModes.contains(FOCUS_MODE_CONTINUOUS_VIDEO)) {
                focusMode = FOCUS_MODE_CONTINUOUS_VIDEO;
            }

            if (focusMode != null) {
                parameters.setFocusMode(focusMode);
                camera.setParameters(parameters);
            }
        }
    }

    private static class FocusSound {
        private final MediaActionSound media;

        private FocusSound() {
            if (Utils.osBuildSdkVersionAtLeast(Build.VERSION_CODES.JELLY_BEAN)) {
                media = new MediaActionSound();
                media.load(MediaActionSound.FOCUS_COMPLETE);
            } else {
                media = null;
            }
        }

        @TargetApi(Build.VERSION_CODES.JELLY_BEAN)
        public void play() {
            if (media != null) {
                media.play(MediaActionSound.FOCUS_COMPLETE);
            }
        }
    }

    public static interface ResultListener {
        public void onCancel();

        public void onSubmit(List<String> photoUriList);
    }

}

If you have use camera.setDisplayOrientation(orientation);
You should not use matrix.postRotate(orientation);

I find out that after setting setDisplayOrientation, the coordinates of focusarea is changed accordingly