渐变转场动画效果

Navigator.of(context).push(PageRouteBuilder(
          transitionDuration: Duration(seconds: 5),
          pageBuilder: (context,animation1,animation2){
                return FadeTransition(
                    opacity: animation1,
                    child: DetailPage(),
                );
           }
));

modal跳转

如果是通过pushNamed方式跳转，则需要在onGenerateRoute里面返回动画转场效果代码
弹出的方式跳转，本质上也是push

Navigator.of(context).push(MaterialPageRoute(
     builder: (context){
         return DetailPage();
     },
     fullscreenDialog: true;
));