php图片等比压缩代码，支持jpg,png,gif，验证gif动画

<?php/** * Created by PhpStorm. * User: as * Date: 2016-12-01 * Time: 8:38 *///图片压缩function ImageCondens($filepase){    list($new_width,$new_height,$imgtype)=getimagesize($filepase);    if($new_width>550){//550为自定义宽度        $scaling=$new_width/550;//缩放比例        $picwidth=($new_width/$scaling);        $picheight=($new_height/$scaling);    }else{        $picwidth=$new_width;        $picheight=$new_height;    }    switch ($imgtype){        case 1:         $fp=fopen($filepase,'rb');         $image_head = fread($fp,1024);            fclose($fp);         if(preg_match("/".chr(0x21).chr(0xff).chr(0x0b).'NETSCAPE2.0'."/",$image_head)){//屏蔽gif动画             echo "<script>alert('系统不支持GIF动画图片');</script>";         }else{             if($image_head){                 header('Content-Type:image/gif');                 $img_wp=imagecreatetruecolor($picwidth,$picheight);                 $img=imagecreatefromgif($filepase);                 imagecopyresampled($img_wp,$img,0,0,0,0,$picwidth,$picheight,$new_width,$new_height);                 imagejpeg($img_wp,null,100);                 imagedestroy($img_wp);             }         }         break;        case 2:            header('Content-Type:image/jpeg');            $img_wp=imagecreatetruecolor($picwidth,$picheight);            $img = imagecreatefromjpeg($filepase);            imagecopyresampled($img_wp,$img,0,0,0,0,$picwidth,$picheight,$new_width,$new_height);            imagejpeg($img_wp,null,100);            imagedestroy($img_wp);            break;        case 3:            header('Content-Type:image/png');            $img_wp=imagecreatetruecolor($picwidth,$picheight);            $img = imagecreatefrompng($filepase);            imagecopyresampled($img_wp,$img,0,0,0,0,$picwidth,$picheight,$new_width,$new_height);            imagejpeg($img_wp,null,100);            imagedestroy($img_wp);            break;    }}ImageCondens("images/3.jpg");