下载和演示：http://www.sucaihuo.com/php/3280.html
引入类库，并返回上传信息
public function crop() {
vendor("crop");
$crop = new \CropAvatar($_POST['avatar_src'], $_POST['avatar_data'], $_FILES['avatar_file']);
$response = array(
'state' => 200,
'message' => $crop->getMsg(),
'result' => $crop->getResult()
);
echo json_encode($response);
}