https://www.runoob.com/php/php-getimagesize.html
https://www.php.net/manual/zh/function.imagecreatefromgif.php
https://www.jb51.net/article/97235.htm
https://www.jb51.net/article/106424.htm
PHP getimagesize函数
凡人做一事，便须全副精神注在此一事，首尾不懈，不可见异思迁，做这样，想那样，坐这山，望那山。人而无恒，终身一无所成。——曾国藩《曾国藩家书》