php上传图片后 实现压缩图片功能

  所用的版本是php7 框架是yii2   <span style="font-family: Arial, Helvetica, sans-serif;"> 程序代码仅供参考，如有不当，大家一起改正 </span><pre code_snippet_id="1815636" snippet_file_name="blog_20160808_1_7833210" name="code" class="php">  <a target=_blank href="http://php.net/manual/zh/ref.image.php" target="_blank">php GD库 和图像处理</a> 资料参考

    public function actionUpload()
    {
        $path = '/uploads/';    //图片存放根目录 根据自己项目路径而定
        $file = $_FILES['fileList']['name'];
        $root = Yii::getAlias('@img').'/img';
        $folder = $path.date('Ymd')."/";
        $pre = rand(999,9999).time();
        $ext = strrchr($file,'.');
        $newName = $pre.$ext;


        $out = ['msg'=>'','status'=>'error','img_url'=>''];


        if(!is_dir($root.$folder))
        {
            if(!mkdir($root.$folder, 0777, true)){
                $out['msg'] = '图片目录创建失败！';
                echo json_encode($out);
                exit;
            }
        }
        $im = $_FILES['fileList']['tmp_name']; //上传图片资源
        $maxwidth="1056"; //设置图片的最大宽度
        $maxheight="500"; //设置图片的最大高度
        $imgname = $root.$folder.$newName;  //图片存放路径 根据自己图片路径而定
        $filetype=$_FILES['fileList']['type'];//图片类型
        $result = $this->thumbImage($im,$maxwidth,$maxheight,$imgname,$filetype);
        if($result){
            $out['msg'] = '图片上传成功';
            $out['status'] = 'success';
            $out['img_url'] = $folder.$newName;
        }else{
            $out['msg'] = '图片上传失败';
        }

        echo json_encode($out);
        exit;
    }


    //压缩图片
    public function thumbImage($im,$maxwidth,$maxheight,$name,$filetype)
    {
        switch ($filetype) {     
            case 'image/pjpeg':     
            case 'image/jpeg':     
                $im = imagecreatefromjpeg($im);    //PHP图片处理系统函数
                break;     
            case 'image/gif':     
                $im = imagecreatefromgif($im);    
                break;     
            case 'image/png':     
                $im = imagecreatefrompng($im);    
                break;
            case 'image/wbmp':     
                $im = imagecreatefromwbmp($im);    
                break;             
        }  


        $resizewidth_tag = $resizeheight_tag = false;
        $pic_width = imagesx($im);
        $pic_height = imagesy($im);


        if(($maxwidth && $pic_width > $maxwidth) || ($maxheight && $pic_height > $maxheight))
        {
$resizewidth_tag = $resizeheight_tag = false;

            if($maxwidth && $pic_width>$maxwidth)
            {
                $widthratio = $maxwidth / $pic_width;
                $resizewidth_tag = true;
            }


            if($maxheight && $pic_height>$maxheight)
            {
                $heightratio = $maxheight / $pic_height;
                $resizeheight_tag = true;
            }


            if($resizewidth_tag && $resizeheight_tag)
            {
                if($widthratio < $heightratio)
                 $ratio = $widthratio;
                else
                 $ratio = $heightratio;
            }


            if($resizewidth_tag && !$resizeheight_tag)
            $ratio = $widthratio;


            if($resizeheight_tag && !$resizewidth_tag)
            $ratio = $heightratio;


            $newwidth = $pic_width * $ratio;
            $newheight = $pic_height * $ratio;



            if(function_exists("imagecopyresampled"))
            {
                $newim = imagecreatetruecolor($newwidth,$newheight);//PHP图片处理系统函数
                imagecopyresampled($newim,$im,0,0,0,0,$newwidth,$newheight,$pic_width,$pic_height);//PHP图片处理系统函数
            }
            else
            {
                $newim = imagecreate($newwidth,$newheight);
                imagecopyresized($newim,$im,0,0,0,0,$newwidth,$newheight,$pic_width,$pic_height);
            }


            switch ($filetype) {     
                case 'image/pjpeg' :     
                case 'image/jpeg' :     
                    $result = imagejpeg($newim,$name);   
                    break;     
                case 'image/gif' :     
                    $result = imagegif($newim,$name);   
                    break;     
                case 'image/png' :     
                    $result = imagepng($newim,$name);    
                    break;
                case 'image/wbmp' :     
                    $result = imagewbmp($newim,$name);    
                    break;             
            } 
            imagedestroy($newim);
        }
        else
        {
            switch ($filetype) {     
                case 'image/pjpeg' :     
                case 'image/jpeg' :     
                    $result = imagejpeg($im,$name);   
                    break;     
                case 'image/gif' :     
                    $result = imagegif($im,$name);   
                    break;     
                case 'image/png' :     
                    $result = imagepng($im,$name);    
                    break;
                case 'image/wbmp' :     
                    $result = imagewbmp($im,$name);    
                    break;             
            }
        }
        return $result; 返回结果
    }