newGsTopLeftOnScaling function
Implementation
Offset newGsTopLeftOnScaling(Offset gsTopLeft, Offset ssFocalPoint, double oldScale, double newScale) {
// gsFocal remains same
// we change gsTopLeft to keep ssFocalPoint same as well
Offset gsFocalPoint = ssToGs(ssFocalPoint, gsTopLeft, oldScale);
return gsFocalPoint - ssFocalPoint / newScale;
}