Flutter-Transiton-1.dart

import 'package:flutter/material.dart';

// usage for this route
//  Navigator.push(context, AppSlideRoute(builder: (context) => new SecondPage(),),);
class AppSlideRoute<T> extends MaterialPageRoute<T> {
  AppSlideRoute({WidgetBuilder builder, RouteSettings settings})
      : super(builder: builder, settings: settings);

  @override
  Widget buildTransitions(BuildContext context, Animation<double> animation,
      Animation<double> secondaryAnimation, Widget child) {
    if (settings.isInitialRoute) return child;
    return new FadeTransition(opacity: animation, child: child);
  }
}