public ActivityBuilder setBackgroundColor(int backgroundColor) {
      mOptions.backgroundColor = backgroundColor;
      return this;
    }
the color of the overlay background around the crop window cover the image parts not in the
crop window.<br>
<i>Default: Color.argb(119, 0, 0, 0)</i>
core/src/main/java/com/theartofdev/edmodo/cropper/CropImage.java