Flutter，image_cropper，如何以特定比率调整大小

import 'package:flutter/material.dart';
import 'package:image_picker/image_picker.dart';
import 'package:image_cropper/image_cropper.dart';

class ImageCropperPage extends StatefulWidget {
  @override
  _ImageCropperPageState createState() => _ImageCropperPageState();
}

class _ImageCropperPageState extends State<ImageCropperPage> {
  File _selectedImage;

  Future<void> _selectAndCropImage() async {
    final picker = ImagePicker();
    final pickedImage = await picker.getImage(source: ImageSource.gallery);

    if (pickedImage != null) {
      final croppedImage = await ImageCropper.cropImage(
        sourcePath: pickedImage.path,
        aspectRatio: CropAspectRatio(ratioX: 1, ratioY: 1), // 设置特定比率
        compressQuality: 100, // 图像质量
        maxWidth: 800, // 最大宽度
        maxHeight: 800, // 最大高度
        androidUiSettings: AndroidUiSettings(
          toolbarTitle: 'Crop Image',
          toolbarColor: Colors.blue,
          toolbarWidgetColor: Colors.white,
          initAspectRatio: CropAspectRatioPreset.original,
          lockAspectRatio: true,
        ),
        iosUiSettings: IOSUiSettings(
          title: 'Crop Image',
        ),
      );

      if (croppedImage != null) {
        setState(() {
          _selectedImage = croppedImage;
        });
      }
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Image Cropper'),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            if (_selectedImage != null)
              Image.file(_selectedImage)
            else
              Text('No image selected'),
            SizedBox(height: 20),
            RaisedButton(
              onPressed: _selectAndCropImage,
              child: Text('Select and Crop Image'),
            ),
          ],
        ),
      ),
    );
  }
}