setSize method
Sets the canvas size and updates dependent values.
Implementation
void setSize(Size size) {
width = size.width;
height = size.height;
sizeMin = min(width, height);
center = Offset(width / 2, height / 2);
spawnArea = Rect.fromLTRB(
center.dx - sizeMin / 100,
center.dy - sizeMin / 100,
center.dx + sizeMin / 100,
center.dy + sizeMin / 100,
);
init();
}