How to resize an image in Flutter

In this Google flutter code example we are going to learn how to resize an image in Flutter.

The code is based on flutter version 1.0.0

Main.dart (App entry point)

import 'package:flutter/material.dart';
import 'resize_image_task-6.dart';

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

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      debugShowCheckedModeBanner: false,
      theme: ThemeData(
        // This is the theme of your application.
        //
        // Try running your application with "flutter run". You'll see the
        // application has a blue toolbar. Then, without quitting the app, try
        // changing the primarySwatch below to Colors.green and then invoke
        // "hot reload" (press "r" in the console where you ran "flutter run",
        // or simply save your changes to "hot reload" in a Flutter IDE).
        // Notice that the counter didn't reset back to zero; the application
        // is not restarted.
        primarySwatch: Colors.blue,
      ),
      //home: MyHomePage(title: 'Flutter Demo Home Page'),
      home: ResizeImage(),
    );
  }
}

resize_image_task-6.dart

import 'package:flutter/material.dart';

class ResizeImage extends StatefulWidget {
  _ResizeImageState createState() => _ResizeImageState();
}

class _ResizeImageState extends State<ResizeImage>
    with SingleTickerProviderStateMixin {
  //Uses a Ticker Mixin for Animations
  Animation<double> _animation;
  AnimationController _animationController;

  @override
  void initState() {
    super.initState();
    _animationController = AnimationController(
        vsync: this,
        duration: Duration(
            seconds:
                2)); //specify the duration for the animation & include `this` for the vsyc
    _animation = Tween<double>(begin: 1.0, end: 3.5).animate(
        _animationController); //use Tween animation here, to animate between the values of 1.0 & 2.5.

    _animation.addListener(() {
      //here, a listener that rebuilds our widget tree when animation.value chnages
      setState(() {});
    });

    _animation.addStatusListener((status) {
      //AnimationStatus gives the current status of our animation, we want to go back to its previous state after completing its animation
      if (status == AnimationStatus.completed) {
        _animationController
            .reverse(); //reverse the animation back here if its completed
      }
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        centerTitle: true,
        title: Text('Resize Image Example'),
      ),
      body: Center(
        child: GestureDetector(
            onTap: () {
              _animationController
                  .forward(); // tapping the button, starts the animation.
            },
            child: Image.asset(
              'assets/images/umbrella.png',
              height: 120.0 * _animation.value,
              width: 80.0 * _animation.value,
            )),
      ),
    );
  }
}

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