public Size getPreviewSize() {
        if (previewSize == null) {
            return null;
        } else if (this.isCameraRotated()) {
            return previewSize.rotate();
        } else {
            return previewSize;
        }
    }
Actual preview size in *current display* rotation. null if not determined yet.

@return preview size
zxing-android-embedded/src/com/journeyapps/barcodescanner/camera/CameraManager.java