Flutter: how can I implement an animated Container from left to right?

Question

• I implement a Room Chat Screen and inside it an animated Container move from left to right and start a again after finish, could someone inform me how to implement it

Answer 1

You need looping animate container, then you can try some Marquee package, such as fast_marquee:

Marquee(
  text: 'Some sample text that takes some space.',
  style: TextStyle(color: Colors.blue, fontWeight: FontWeight.bold),
  velocity: 100,
  blankSpace: 10,
  startPadding: 10,
  reverse: true,
  bounce: true,
  startAfter: const Duration(seconds: 2),
  pauseAfterRound: const Duration(seconds: 1),
  numberOfRounds: 5,
  showFadingOnlyWhenScrolling: false,
  fadingEdgeStartFraction: 0.05,
  fadingEdgeEndFraction: 0.05,
  curve: Curves.easeInOut,
)

OR

try AnimatedPositioned:

import 'package:flutter/material.dart';

void main() => runApp(const MyApp());

/// This is the main application widget.
class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  static const String _title = 'Flutter Code Sample';

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: _title,
      home: Scaffold(
        appBar: AppBar(title: const Text(_title)),
        body: const Center(
          child: MyStatefulWidget(),
        ),
      ),
    );
  }
}

/// This is the stateful widget that the main application instantiates.
class MyStatefulWidget extends StatefulWidget {
  const MyStatefulWidget({Key? key}) : super(key: key);

  @override
  State<MyStatefulWidget> createState() => _MyStatefulWidgetState();
}

/// This is the private State class that goes with MyStatefulWidget.
class _MyStatefulWidgetState extends State<MyStatefulWidget> {
  bool selected = false;

  @override
  Widget build(BuildContext context) {
    return SizedBox(
      width: 200,
      height: 350,
      child: Stack(
        children: <Widget>[
          AnimatedPositioned(
            width: selected ? 200.0 : 50.0,
            height: selected ? 50.0 : 200.0,
            top: selected ? 50.0 : 150.0,
            duration: const Duration(seconds: 2),
            curve: Curves.fastOutSlowIn,
            child: GestureDetector(
              onTap: () {
                setState(() {
                  selected = !selected;
                });
              },
              child: Container(
                color: Colors.blue,
                child: const Center(child: Text('Tap me')),
              ),
            ),
          ),
        ],
      ),
    );
  }
}