Changing Tab

BouncingBottomNavigation.dart

 void onChangeTab(int index) {
    if (itemWidth == null) itemWidth = MediaQuery.of(context).size.width / 5;
  
    setState(() {
      selectedIndex = index;
    });

    var nextPos = index * itemWidth + 10;
    pivotPoints[0] = pivotPoints[2];
    double px = (nextPos + pivotPoints[2].dx) / 2; 
    animationController.reset();
    pivotPoints[1] = Offset(px, -150);
    pivotPoints[2] = Offset(nextPos, -25); 
    animationController.forward();
  }