code: @Override
      public void setup(IChemModel chemModel, Rectangle screen) {
          this.setScale(chemModel);
          Rectangle2D bounds = BoundsCalculator.calculateBounds(chemModel);
          if (bounds != null) this.modelCenter = new Point2d(bounds.getCenterX(), bounds.getCenterY());
          this.drawCenter = new Point2d(screen.getCenterX(), screen.getCenterY());
          this.setup();
      }
docs: Setup the transformations necessary to draw this Chem Model.
  
  @param chemModel
  @param screen