转自https://www.jianshu.com/p/12ee9456eb2e

pubspec.yaml 引入 flutter_drag_scale  点击右上角的packages get  也就是flutter packages get  然后 main.dart 中引入 

dependencies:
  flutter:
    sdk: flutter
  flutter_drag_scale:
    git: https://github.com/LiuC520/flutter_drag_scale.git

 

main.dart

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

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Container(
      height: 400.0,
      width: 400,
      child: Center(
        child: DragScaleContainer(
          doubleTapStillScale: true,
          child: new Image(
            image: new NetworkImage(
                'http://h.hiphotos.baidu.com/zhidao/wh%3D450%2C600/sign=0d023672312ac65c67506e77cec29e27/9f2f070828381f30dea167bbad014c086e06f06c.jpg'),
          ),
        ),
      ),
    );
  }
}