PHP压缩上传图片

发布时间：2023-09-06 01:38责任编辑：郭大石关键词：PHP 上传图片

最近手上的项目页面要显示很多图片，虽然用了jQuery的lazyload，但是效果并没理想，滑动到一个区域还要比较长的时间图片才完全显示出来。于是想着将上传上去的900KB+压缩备份一份缩略图。
PHP压缩图片两个步骤：
1、添加类

//php生成缩略图片的类class ResizeImage{ ???public $type;//图片类型 ???public $width;//实际宽度 ???public $height;//实际高度 ???public $resize_width;//改变后的宽度 ???public $resize_height;//改变后的高度 ???public $cut;//是否裁图 ???public $srcimg;//源图象 ????public $dstimg;//目标图象地址 ???public $im;//临时创建的图象 ???public $quality;//图片质量 ???public $img_array=array(‘jpg‘,‘png‘,‘gif‘); ???//http://www.phpernote.com/php-function/782.html ???function __construct($img,$wid,$hei,$c,$dstpath,$quality=100){ ???????$this->srcimg=$img; ???????$this->resize_width=$wid; ???????$this->resize_height=$hei; ???????$this->cut=$c; ???????$this->quality=$quality; ???????//$this->type=strtolower(substr(strrchr($this->srcimg,‘.‘),1));//图片的类型 ???????$this->type=$this->checkFileType($this->srcimg);//更为严格的检测图片类型 ???????if(!in_array($this->type,$this->img_array)){ ???????????return ‘‘; ???????} ???????$this->initi_img();//初始化图象 ???????$this -> dst_img($dstpath);//目标图象地址 ???????$this->width=imagesx($this->im); ???????$this->height=imagesy($this->im); ???????$this->newimg();//生成图象 ???????ImageDestroy($this->im); ???} ???function newimg(){ ???????$resize_ratio=($this->resize_width)/($this->resize_height);//改变后的图象的比例 ???????$ratio=($this->width)/($this->height);//实际图象的比例 ???????if(($this->cut)==‘1‘){//裁图 ???????????if(function_exists(‘imagepng‘)&&(str_replace(‘.‘,‘‘,PHP_VERSION)>=512)){//针对php版本大于5.12参数变化后的处理情况 ???????????????$quality=9; ???????????} ???????????if($ratio>=$resize_ratio){//高度优先 ???????????????$newimg=imagecreatetruecolor($this->resize_width,$this->resize_height); ???????????????//上色 ????????????????$color=imagecolorallocate($newimg,255,255,255); ????????????????//设置透明 ????????????????imagecolortransparent($newimg,$color); ????????????????imagefill($newimg,0,0,$color); ????????????????imagecopyresampled($newimg,$this->im,0,0,0,0,$this->resize_width,$this->resize_height,(($this->height)*$resize_ratio),$this->height); ???????????????imagejpeg($newimg,$this->dstimg,$this->quality); ???????????} ???????????if($ratio<$resize_ratio){//宽度优先 ???????????????$newimg=imagecreatetruecolor($this->resize_width,$this->resize_height); ???????????????//上色 ????????????????$color=imagecolorallocate($newimg,255,255,255); ????????????????//设置透明 ????????????????imagecolortransparent($newimg,$color); ????????????????imagefill($newimg,0,0,$color); ????????????????imagecopyresampled($newimg,$this->im,0,0,0,0,$this->resize_width,$this->resize_height,$this->width,(($this->width)/$resize_ratio)); ???????????????imagejpeg($newimg,$this->dstimg,$this->quality); ???????????} ???????}else{//不裁图 ???????????if($ratio>=$resize_ratio){ ???????????????$newimg=imagecreatetruecolor($this->resize_width,($this->resize_width)/$ratio); ???????????????//上色 ????????????????$color=imagecolorallocate($newimg,255,255,255); ????????????????//设置透明 ????????????????imagecolortransparent($newimg,$color); ????????????????imagefill($newimg,0,0,$color); ????????????????imagecopyresampled($newimg,$this->im,0,0,0,0,$this->resize_width,($this->resize_width)/$ratio,$this->width,$this->height); ???????????????imagejpeg($newimg,$this->dstimg,$this->quality); ???????????} ???????????if($ratio<$resize_ratio){ ???????????????$newimg=imagecreatetruecolor(($this->resize_height)*$ratio,$this->resize_height); ???????????????//上色 ????????????????$color=imagecolorallocate($newimg,255,255,255); ????????????????//设置透明 ????????????????imagecolortransparent($newimg,$color); ????????????????imagefill($newimg,0,0,$color); ????????????????imagecopyresampled($newimg,$this->im,0,0,0,0,($this->resize_height)*$ratio,$this->resize_height,$this->width,$this->height); ???????????????imagejpeg($newimg,$this->dstimg,$this->quality); ???????????} ???????} ???} ???function initi_img(){//初始化图象 ???????if($this->type==‘jpg‘){ ???????????$this->im=imagecreatefromjpeg($this->srcimg); ???????} ???????if($this->type==‘gif‘){ ???????????$this->im=imagecreatefromgif($this->srcimg); ???????} ???????if($this->type==‘png‘){ ???????????$this->im=imagecreatefrompng($this->srcimg); ???????} ???} ???function dst_img($dstpath){//图象目标地址 ???????$full_length=strlen($this->srcimg); ???????$type_length=strlen($this->type); ???????$name_length=$full_length-$type_length; ???????$name=substr($this->srcimg,0,$name_length-1); ???????$this->dstimg=$dstpath; ???????//echo $this->dstimg; ???} ???//读取文件前几个字节 判断文件类型 ???function checkFileType($filename){ ???????$file=fopen($filename,‘rb‘); ???????$bin=fread($file,2); //只读2字节 ???????fclose($file); ???????$strInfo =@unpack("c2chars",$bin); ???????$typeCode=intval($strInfo[‘chars1‘].$strInfo[‘chars2‘]); ???????$fileType=‘‘; ???????switch($typeCode){ ???????????case 7790: ???????????????$fileType=‘exe‘; ???????????break; ???????????case 7784: ???????????????$fileType=‘midi‘; ???????????break; ???????????case 8297: ???????????????$fileType=‘rar‘; ???????????break; ???????????case 255216: ???????????????$fileType=‘jpg‘; ???????????break; ???????????case 7173: ???????????????$fileType=‘gif‘; ???????????break; ???????????case 6677: ???????????????$fileType=‘bmp‘; ???????????break; ???????????case 13780: ???????????????$fileType=‘png‘; ???????????break; ???????????default: ???????????????$fileType=‘unknown‘.$typeCode; ???????????break; ???????} ???????if($strInfo[‘chars1‘]==‘-1‘&&$strInfo[‘chars2‘]==‘-40‘){ ???????????return ‘jpg‘; ???????} ???????if($strInfo[‘chars1‘]==‘-119‘&&$strInfo[‘chars2‘]==‘80‘){ ???????????return ‘png‘; ???????} ???????return $fileType; ???}}

2、压缩图片

$resizeimage=new ResizeImage($file_path,300,169,0,$newname);

ResizeImage会将你正在上传的图片压缩至相应尺寸，同时上传。参数意义(路径, width, height, 是否截图, 图片名称)，$file_path的根目录是这个php所在的文件夹，可以修改调整至相应路径。
通过该方法，成功将900+kb的图片压缩至40+kb，图片加载迅速很多。

PHP压缩上传图片

原文地址：https://www.cnblogs.com/xiaoleiel/p/8333962.html

PHP压缩上传图片

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