php 缩略图封装的方法

/**
 * PHP生成缩略图
 * @param $basepath /原文件地址
 * @param $des_w    /缩略图的宽
 * @param $des_h    /缩略图的高
 * @param $style    /规则名称
 * @param $line     /连接符
 * @param int $save / 展示方式 0展示缩略图(默认) 1保存缩略图
 * @return string
 */
function thumb($basepath, $des_w, $des_h, $style, $line, $save = 0)
{
    if(!file_exists($basepath)) {
        return 'file not exists';
    }
    $fileExt = substr(basename($basepath), strrpos(basename($basepath), '.'));
    $file = basename(basename($basepath), $fileExt);
    $fileinfo = getimagesize($basepath);
    $src_w = $fileinfo[0];
    $src_h = $fileinfo[1];
    $type = $fileinfo[2];
    $type_array = [1=> 'gif', 2=> 'jpeg', 3=> 'png'];
    $type_str = $type_array[$type];//jpeg

    $fun_str = 'imagecreatefrom';
    $function = $fun_str.$type_str;//imagecreatefromjpeg
    //原图片资源
    $src_img = $function($basepath);

    $srcAvg = round($src_w / $src_h, 1);
    if($des_h == 0 && $des_w != 0) {
        //固定宽
        $des_width = $des_w;
        $des_height = round($des_w / $srcAvg);
    } elseif ($des_w == 0 && $des_h != 0) {
        //固定高
        $des_height = $des_h;
        $des_width = round($des_height * $srcAvg);
    } elseif ($des_w == 0 && $des_h == 0) {
        //原图
        $des_width = $src_w;
        $des_height = $src_h;
    } elseif ($des_w != 0 && $des_h != 0) {
        $des_width = $des_w;
        $des_height = $des_h;
    }
    $des_img = imagecreatetruecolor($des_width, $des_height);
    imagecopyresampled($des_img, $src_img, 0, 0, 0, 0, $des_width, $des_height, $src_w, $src_h);

    $thumb = 'image'.$type_str;//imagejpeg
    if($save) {
        //保存缩略图
        $filename = dirname($basepath) . '/' . $file.$line.$style.$fileExt;//保存
        $thumb($des_img, $filename);
    } else {
        header('Content-type: image/'. $type_str .'');
        $thumb($des_img);//展示图片
    }
    imagedestroy($des_img);
    imagedestroy($src_img);
    if($save) {
        return $filename;
    } else {
        return true;
    }
}