onDragEnd method
Implementation
void onDragEnd(DragEndDetails details)
{
double velocity = details.velocity.pixelsPerSecond.dx.abs();
double distance = (last - start);
if ((swiping) && (distance > 50) && (velocity > 100)) NavigationManager().back(1);
swiping = false;
start = 0;
last = 0;
}