How is the getBBox() SVGRect calculated?

Question

I have a g element that contains one or more path elements. As I mentioned in another question, I scale and translate the g element by

Answer 1

SVG groups have nasty practice - not to accumulate all transformations made. I have my way to cope with this issue. I'm using my own attributes to store current transformation data which I include in any further transformation. Use XML compatible attributes like alttext, value, name....or just x and y for storing accumulated value as atribute.

Example:

Therefore when I'm making transformations I'm taking those handmade attribute values, and when writing it back, I'm writing both transform and same value with attributes I made just for keeping all accumulated values.

Example for rotation:

function symbRot(evt) {

  evt.target.ondblclick = function () {

    stopBlur();
    var ptx=symbG.parentNode.lastChild.getAttribute("cx");
    var pty=symbG.parentNode.lastChild.getAttribute("cy");
    var currRot=symbG.getAttributeNS(null, "alttext");

    var rotAng;
    if (currRot == 0) {
      rotAng = 90
    } else if (currRot == 90) {
      rotAng = 180
    } else if (currRot == 180) {
      rotAng = 270
    } else if (currRot == 270) {
      rotAng = 0
    };
    symbG.setAttributeNS(null, "transform", "rotate(" + rotAng + "," + ptx + ", " + pty + ")");
    symbG.setAttributeNS(null, "alttext", rotAng );
  };
}