为此，您可以使用copyCrop函数。这里有一个例子

import 'dart:ui' as ui;
import 'package:image/image.dart' as img;

final double left = ...;
final double top = ...;
final double width = ...;
final double height = ...;

final bytes = File(image.path).readAsBytesSync();
final rawImage = img.decodeImage(bytes);

final pictureRecorder = ui.PictureRecorder();
final canvas = Canvas(pictureRecorder);
final paint = Paint();
canvas.drawImage(imgCodec, Offset.zero, paint);

final croppedImage = img.copyCrop(
  rawImage,
  left.toInt(),
  top.toInt(),
  width.toInt(),
  height.toInt(),
);

final croppedBytes = img.encodePng(croppedImage);

final croppedImageFile = await saveImageToDisk(croppedBytes);
model.img = croppedImageFile.path;

在上面的代码中，替换...与裁剪矩形的实际值。