Flutter -如何将图表保存为设备中的图像或发送到服务器？

dependencies:
  flutter_chart: ^版本号
  flutter_local_notifications: ^版本号

import 'package:flutter/material.dart';
import 'package:flutter_chart/flutter_chart.dart';
import 'package:flutter_local_notifications/flutter_local_notifications.dart';
import 'dart:io';
import 'dart:typed_data';

Chart chart = Chart(
  datasets: [
    ChartDataset(
      data: [5, 10, 15, 20, 25],
      color: Colors.blue,
    ),
  ],
);

Canvas canvas = Canvas(Size(200, 200));
chart.draw(canvas);

final recorder = PictureRecorder();
final canvas = Canvas(recorder);
chart.draw(canvas);
final picture = recorder.endRecording();
final image = await picture.toImage(200, 200);
final byteData = await image.toByteData(format: ImageByteFormat.png);
final Uint8List bytes = byteData.buffer.asUint8List();

// 保存图像文件到设备中
final directory = await getTemporaryDirectory();
final file = File('${directory.path}/chart.png');
await file.writeAsBytes(bytes);

import 'package:http/http.dart' as http;

final request = http.MultipartRequest('POST', Uri.parse('服务器URL'));
final file = File('${directory.path}/chart.png');
final stream = http.ByteStream(file.openRead());
final length = await file.length();

final multipartFile = http.MultipartFile(
  'file',
  stream,
  length,
  filename: file.path,
);

request.files.add(multipartFile);

final response = await request.send();
final responseString = await response.stream.bytesToString();

// 处理服务器响应