@RequiresPermission(Manifest.permission.CAMERA)
 private void startIfReady() throws IOException, SecurityException {
   if (mStartRequested && mSurfaceAvailable) {
     mCameraSource.start(mSurfaceView.getHolder());
     if (mOverlay != null) {
       Size size = mCameraSource.getPreviewSize();
       int min = Math.min(size.getWidth(), size.getHeight());
       int max = Math.max(size.getWidth(), size.getHeight());
       if (isPortraitMode()) {
         // Swap width and height sizes when in portrait, since it will be rotated by
         // 90 degrees
         mOverlay.setCameraInfo(min, max, mCameraSource.getCameraFacing());
       } else {
         mOverlay.setCameraInfo(max, min, mCameraSource.getCameraFacing());
       }
       mOverlay.clear();
     }
     mStartRequested = false;
   }
 }
  @Override
  protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
    int width = 320;
    int height = 240;
    if (mCameraSource != null) {
      Size size = mCameraSource.getPreviewSize();
      if (size != null) {
        width = size.getWidth();
        height = size.getHeight();
      }
    }

    // Swap width and height sizes when in portrait, since it will be rotated 90 degrees
    if (isPortraitMode()) {
      int tmp = width;
      //noinspection SuspiciousNameCombination
      width = height;
      height = tmp;
    }

    final int layoutWidth = right - left;
    final int layoutHeight = bottom - top;

    // Computes height and width for potentially doing fit width.
    int childWidth = layoutWidth;
    int childHeight = (int) (((float) layoutWidth / (float) width) * height);

    // If height is too tall using fit width, does fit height instead.
    if (childHeight > layoutHeight) {
      childHeight = layoutHeight;
      childWidth = (int) (((float) layoutHeight / (float) height) * width);
    }

    for (int i = 0; i < getChildCount(); ++i) {
      getChildAt(i).layout(0, 0, childWidth, childHeight);
    }

    try {
      startIfReady();
    } catch (SecurityException se) {
      Log.e(TAG, "Do not have permission to start the camera", se);
    } catch (IOException e) {
      Log.e(TAG, "Could not start camera source.", e);
    }
  }
 public void release() {
   if (mCameraSource != null) {
     mCameraSource.release();
     mCameraSource = null;
   }
 }
 public void stop() {
   if (mCameraSource != null) {
     mCameraSource.stop();
   }
 }