import 'package:flutter/material.dart'; Route buildQuickSwitchRoute(Widget page) { return PageRouteBuilder( pageBuilder: (context, animation, secondaryAnimation) => page, transitionDuration: const Duration(milliseconds: 220), reverseTransitionDuration: const Duration(milliseconds: 200), transitionsBuilder: (context, animation, secondaryAnimation, child) { // Pure crossfade — no positional slide, so the shared top chrome // (app bar + Contacts/Channels toggle) stays rock-steady while switching. return FadeTransition( opacity: CurvedAnimation( parent: animation, curve: Curves.easeOut, reverseCurve: Curves.easeIn, ), child: child, ); }, ); }