parser method
Implementation
@override
Future<void> parser(List<String> arguments) async {
final argResults = argParser.parse(arguments);
final watch = argResults['watch'];
final output = argResults['output'];
logger.i('generate images...');
var result = await _generateImages(watch, output);
// 写入成功后, 检查pubspec.yaml文件是否注册了assets/images, 如果没有注册则注册该资源目录
if (result) result = await registerAssets('assets/images/');
// 如果本次注册了资源,执行"flutter pub get"命令
if (result) await runFlutterPubGet();
logger.i('Process finished.');
}