Flutter将屏幕上的图像保存到设备中

import 'dart:typed_data';
import 'dart:ui' as ui;
import 'package:flutter/material.dart';
import 'package:flutter/rendering.dart';
import 'package:path_provider/path_provider.dart';
import 'package:image/image.dart' as img;
import 'package:flutter/services.dart';

class ScreenCapture extends StatefulWidget {
  @override
  _ScreenCaptureState createState() => _ScreenCaptureState();
}

class _ScreenCaptureState extends State<ScreenCapture> {
  GlobalKey _globalKey = GlobalKey();

  Future<void> _captureAndSave() async {
    try {
      RenderRepaintBoundary boundary =
          _globalKey.currentContext.findRenderObject();
      ui.Image image = await boundary.toImage();
      ByteData byteData =
          await image.toByteData(format: ui.ImageByteFormat.png);
      Uint8List pngBytes = byteData.buffer.asUint8List();

      final directory = await getExternalStorageDirectory();
      final imagePath = '${directory.path}/screenshot.png';
      final imageFile = File(imagePath);
      await imageFile.writeAsBytes(pngBytes);

      showDialog(
        context: context,
        builder: (context) => AlertDialog(
          title: Text('截图已保存'),
          content: Text('路径：$imagePath'),
          actions: [
            FlatButton(
              child: Text('确定'),
              onPressed: () => Navigator.of(context).pop(),
            ),
          ],
        ),
      );
    } catch (e) {
      print(e.toString());
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('屏幕截图'),
      ),
      body: RepaintBoundary(
        key: _globalKey,
        child: Center(
          child: Text('要截图的内容'),
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _captureAndSave,
        child: Icon(Icons.camera_alt),
      ),
    );
  }
}

void main() {
  runApp(MaterialApp(
    home: ScreenCapture(),
  ));
}