PHP简单实现图片格式转换(jpg转png，gif转png等)

 /** * 图片格式转换 * @param string $image_path 文件路径或url * @param string $to_ext 待转格式，支持png,gif,jpeg,wbmp,webp,xbm * @param null|string $save_path 存储路径，null则返回二进制内容，string则返回true|false * @return boolean|string $save_path是null则返回二进制内容，是string则返回true|false * @throws Exception * @author klinson  */ function transform_image($image_path, $to_ext = 'png', $save_path = null) { if (! in_array($to_ext, ['png', 'gif', 'jpeg', 'wbmp', 'webp', 'xbm'])) { throw new \Exception('unsupport transform image to ' . $to_ext); } switch (exif_imagetype($image_path)) { case IMAGETYPE_GIF : $img = imagecreatefromgif($image_path); break; case IMAGETYPE_JPEG : case IMAGETYPE_JPEG2000: $img = imagecreatefromjpeg($image_path); break; case IMAGETYPE_PNG: $img = imagecreatefrompng($image_path); break; case IMAGETYPE_BMP: case IMAGETYPE_WBMP: $img = imagecreatefromwbmp($image_path); break; case IMAGETYPE_XBM: $img = imagecreatefromxbm($image_path); break; case IMAGETYPE_WEBP: //(从 PHP 7.1.0 开始支持) $img = imagecreatefromwebp($image_path); break; default : throw new \Exception('Invalid image type'); } $function = 'image'.$to_ext; if ($save_path) { return $function($img, $save_path); } else { $tmp = __DIR__.'/'.uniqid().'.'.$to_ext; if ($function($img, $tmp)) { $content = file_get_contents($tmp); unlink($tmp); return $content; } else { unlink($tmp); throw new \Exception('the file '.$tmp.' can not write'); } } } 

 // 转换后保存在test.png-600 transform_image($url, 'png', './test.png-600'); transform_image($filepath, 'png', './test.png-600'); // 转换后二进制结果直接返回 transform_image($url, 'png'); transform_image($filepath, 'png');