php图片无损压缩的问题解决

代码如下

 <?php

 namespace App\Contract;

 use Carbon\Carbon;

 /**
  * 图片压缩封装类
  * @author jackie <2019.11.20>
  */
 class CompressImageContract
 {
     /**
      * desription 压缩图片
      * @param sting $imgsrc 图片路径(服務器絕對路徑)
      * @param string $imgdst 压缩后保存路径(服務器絕對路徑)
      */
     public function image_png_size_add($imgsrc, $imgdst)
     {
         $zip_width = config("config.zip_width");//讀取默認最小寬度
         $zip_height = config("config.zip_height");//讀取默認最小高度
         $zip_per = config("config.zip_per");//讀取默認壓縮比例

         list($width, $height, $type) = getimagesize($imgsrc);
         $new_width = ceil(($width > 600 ? 600 : $width) * $zip_per);
         $new_height = ceil(($height > 600 ? 600 : $height) * $zip_per);
         /*$width = 3000;
         $height = 150;
         $new_width = $width * $zip_per;
         $new_height = $height * $zip_per;*/

         //寬度、高度都小於最小值，取最大比例值
         if ($new_width < $zip_width && $new_height < $zip_height) {
             $formatWidth = sprintf("%.1f", $zip_width / $width);
             $perWidth = $formatWidth + 0.1;

             $formatHeight = sprintf("%.1f", $zip_height / $height);
             $perHeight = $formatHeight + 0.1;

             $per = $perWidth >= $perHeight ? $perWidth : $perHeight;
             $per = $per < 1 ? $per : 1;//壓縮比例不能大於1
             $new_width = ceil($width * $per);
             $new_height = ceil($height * $per);
             //return $new_width.'/'.$new_height.$per.'/**1';
         }

         //寬度小於最小值，高度正常，計算寬度最小比例
         if ($new_width < $zip_width && $new_height > $zip_height) {
             $formatWidth = sprintf("%.1f", $zip_width / $width);
             $per = $formatWidth + 0.1;
             $per = $per < 1 ? $per : 1;//壓縮比例不能大於1
             $new_width = ceil($width * $per);
             $new_height = ceil($height * $per);
             //return $new_width . '/' . $new_height . '/' . $per . '/**2';
         }
         //寬度正常，高度小於最小值，計算高度最小比例
         if ($new_width > $zip_width && $new_height < $zip_height) {
             $formatHeight = sprintf("%.1f", $zip_height / $height);
             $per = $formatHeight + 0.1;
             $per = $per < 1 ? $per : 1;//壓縮比例不能大於1
             $new_width = ceil($width * $per);
             $new_height = ceil($height * $per);
             //return $new_width . '/' . $new_height . '/' . $per . '/**3';
         }
         //return $new_width . '/' . $new_height . '/' . $per . '/**4';

         switch ($type) {
             case 1:
                 $giftype = check_gifcartoon($imgsrc);
                 if ($giftype) {
                     header('Content-Type:image/gif');
                     $image_wp = imagecreatetruecolor($new_width, $new_height);
                     $image = imagecreatefromgif($imgsrc);
                     imagecopyresampled($image_wp, $image, 0, 0, 0, 0, $new_width, $new_height, $width, $height);
                     imagejpeg($image_wp, $imgdst, 75);
                     imagedestroy($image_wp);
                 }
                 break;
             case 2:
                 header('Content-Type:image/jpeg');
                 $image_wp = imagecreatetruecolor($new_width, $new_height);
                 $image = imagecreatefromjpeg($imgsrc);
                 imagecopyresampled($image_wp, $image, 0, 0, 0, 0, $new_width, $new_height, $width, $height);
                 imagejpeg($image_wp, $imgdst, 75);
                 imagedestroy($image_wp);
                 break;
             case 3:
                 header('Content-Type:image/png');
                 $image_wp = imagecreatetruecolor($new_width, $new_height);
                 $image = imagecreatefrompng($imgsrc);
                 imagecopyresampled($image_wp, $image, 0, 0, 0, 0, $new_width, $new_height, $width, $height);
                 imagejpeg($image_wp, $imgdst, 75);
                 imagedestroy($image_wp);
                 break;
         }
     }

     /**
      * desription 判断是否gif动画
      * @param sting $image_file图片路径
      * @return boolean t 是 f 否
      */
     public function check_gifcartoon($image_file)
     {
         $fp = fopen($image_file, 'rb');
         $image_head = fread($fp, 1024);
         fclose($fp);
         return preg_match("/" . chr(0x21) . chr(0xff) . chr(0x0b) . 'NETSCAPE2.0' . "/", $image_head) ? false : true;
     }
 }

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