docs: public Element setupCanvas(SVGPlot svgp, ProjectionParallel proj, double width, double height) {
      Element layer = SVGUtil.svgElement(svgp.getDocument(), SVGConstants.SVG_G_TAG);
      final String transform = SVGUtil.makeMarginTransform(width, height, size[0], size[1], margins[0], margins[1], margins[2], margins[3]);
      SVGUtil.setAtt(layer, SVGConstants.SVG_TRANSFORM_ATTRIBUTE, transform);
      return layer;
    }