toAlignment method
Alignment goes from (-1, -1) to (1, 1) This method converts an Offset with (0,0) to (1,1) to an Alignment
Implementation
Alignment toAlignment(Rect rect) {
return Alignment(
(dx / rect.size.width) * 2 - 1,
(dy / rect.size.height) * 2 - 1,
);
}