如何使用Flutter从图像中提取RGB颜色值？

import 'package:flutter/material.dart';
import 'package:image_picker/image_picker.dart';
import 'package:image/image.dart' as img;

Future<String> pickImage() async {
  var image = await ImagePicker.pickImage(source: ImageSource.gallery);
  return image.path;
}

List<int> extractRGB(String imagePath) {
  img.Image image = img.decodeImage(File(imagePath).readAsBytesSync());

  int totalRed = 0;
  int totalGreen = 0;
  int totalBlue = 0;

  for (int x = 0; x < image.width; x++) {
    for (int y = 0; y < image.height; y++) {
      int pixel = image.getPixel(x, y);
      int red = img.getRed(pixel);
      int green = img.getGreen(pixel);
      int blue = img.getBlue(pixel);
      totalRed += red;
      totalGreen += green;
      totalBlue += blue;
    }
  }

  int pixelCount = image.width * image.height;
  int averageRed = totalRed ~/ pixelCount;
  int averageGreen = totalGreen ~/ pixelCount;
  int averageBlue = totalBlue ~/ pixelCount;

  return [averageRed, averageGreen, averageBlue];
}

class ColorExtractionApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: Text('Color Extraction'),
        ),
        body: Center(
          child: RaisedButton(
            child: Text('Pick Image'),
            onPressed: () {
              pickImage().then((imagePath) {
                List<int> rgb = extractRGB(imagePath);
                showDialog(
                  context: context,
                  builder: (BuildContext context) {
                    return AlertDialog(
                      title: Text('RGB Values'),
                      content: Text('Red: ${rgb[0]}\nGreen: ${rgb[1]}\nBlue: ${rgb[2]}'),
                      actions: <Widget>[
                        FlatButton(
                          child: Text('OK'),
                          onPressed: () {
                            Navigator.of(context).pop();
                          },
                        ),
                      ],
                    );
                  },
                );
              });
            },
          ),
        ),
      ),
    );
  }
}

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