App_Flutter/lib/view/animation.dart

import 'package:flutter/material.dart';
import 'package:flutter/services.dart';

class DemoPage extends StatefulWidget {
  const DemoPage({Key? key}) : super(key: key);

  @override
  State<DemoPage> createState() => _DemoPageState();
}

class _DemoPageState extends State<DemoPage> with SingleTickerProviderStateMixin{
  AnimationController? controller0;
  Animation<double>? widthAni;
  // late Animation alphaAnimation;
  // AnimationController controller1;
  double top = -30.0;
  double opacity1 = 0.0;
  @override
  Widget build(BuildContext context) {
    SystemChrome.setSystemUIOverlayStyle(SystemUiOverlayStyle.dark);
    return Container(
      color: Colors.white,
      child: SizedBox(width: 100.0,height: 100.0,child: Container(color: Colors.orange,),),
      // child: Container(height: 100,width: 100,color: Colors.blue,),
      // child: Stack(
      //   children: [
      //     // AnimatedPositioned(
      //     //   child: AnimatedOpacity(opacity: opacity1,child: Container(height: 50,width: widthAni!.value,color: Colors.red,),duration: const Duration(milliseconds: 200),),
      //     //   duration: const Duration(milliseconds: 200),
      //     //   top: top,
      //     // ),
      //     Container(height: widthAni!.value,width: widthAni!.value,color: Colors.blue,)
      //   ],
      // ),
    );
  }

  @override
  void initState() {
    super.initState();

    // controller0 = AnimationController(vsync: this,duration: const Duration(milliseconds: 2000));
    // controller0!.addStatusListener((status) { });
    // widthAni = Tween(begin: 50.0, end: 200.0).animate(CurvedAnimation(parent: controller0!, curve: const Interval(0.0,1.0)));
    // controller0!.forward();


    // alphaAnimation = 
    // Timer(const Duration(seconds: 1), (){
    //   controller0!.forward();
    //   setState(() {
    //     top = 60;
    //     opacity1 =1;
    //   });
    // });
  }
}