Calculate point's real position after svg transforming.

GetSVGPoint

/**
 *
 *
 * @param {SVGSVGElement} svg: root svg element
 * @param {number} x
 * @param {number} y
 * @param {SVGMatrix} ctm: element.getScreemCTM()
 * @returns {SVGPoint} real position in container
 */
function GetPoint(svg: SVGSVGElement, x: number, y: number, ctm: SVGMatrix): SVGPoint {
  let pt1 = svg.createSVGPoint();
  pt1.x = x;
  pt1.y = y;
  const rootCTM = svg.getScreenCTM()!;
  return pt1.matrixTransform(rootCTM.inverse().multiply(ctm));
}