Flutter: Lifecycle of a Widget and Navigation

I ended up stopping the controller before I navigate to the other page and restart it, when pop() is called.

//navigate to new page
void didDetectBarcode(String barcode) {
   controller.stop();
   Navigator.of(context)
       .push(...)
       .then(() => controller.start()); //future completes when pop() returns to this page

}

Another solution would be to set the maintainState property of the route that opens ScanPage to false.