anchor.diff:  
     Rect _visibleArea;
   
  -  Rect get visibleArea => _visibleArea;
  +  Rect get visibleArea {
  +    if (_visibleArea == null) _calcTransformMatrix();
  +    return _visibleArea;
  +  }
   
     // Setup
   
  
positive.code:         break;
      }
  
      _transformMatrix.translate(offsetX, offsetY);
      _transformMatrix.scale(scaleX, scaleY);
  
      return _transformMatrix;
    }
  
    void _invalidateTransformMatrix() {
      _transformMatrix = null;
      _rootNode._invalidateToBoxTransformMatrix();
    }
  
negative.code:     _transformMode = value;
  
      // Invalidate stuff
      markNeedsLayout();
    }
  
    /// The transform mode used by the [SpriteBox].
  