bezier

  // get the x:y position at this ratio (t)
  Point _positionAtBezierRatio(num t, EditableBezierPoint p1, EditableBezierPoint p2) {
    return new Point(_xAtBezierRatio(t, p1, p2), _yAtBezierRatio(t, p1, p2));
  }
  num _xAtBezierRatio(num t, EditableBezierPoint p1, EditableBezierPoint p2) {
    num sX = p1.x;
    num cX1 = p1.cx2;
    num eX = p2.x;
    num cX2 =p2.cx1;

    num xTmp = (pow(1 - t, 3) * sX) +
        (3 * pow(1 - t, 2) * t * cX1) +
        (3 * (1 - t) * pow(t, 2) * cX2) +
        (pow(t, 3) * eX);

    return xTmp;
  }

  num _yAtBezierRatio(num t, EditableBezierPoint p1, EditableBezierPoint p2) {
    num sY = p1.y;
    num cY1 = p1.cy2;
    num eY = p2.y;
    num cY2 =p2.cy1;

    num yTmp = (pow(1 - t, 3) * sY) +
        (3 * pow(1 - t, 2) * t * cY1) +
        (3 * (1 - t) * pow(t, 2) * cY2) +
        (pow(t, 3) * eY);

    return yTmp;
  }