Solution to the poor quality of thumbnails generated by php-PHP Tutorial-php.cn

Solution to the poor quality of thumbnails generated by php

小云云

Release： 2023-03-17 21:10:01

Original

1741 people have browsed it

I believe that you have encountered the problem of poor thumbnail quality during development. This article mainly introduces the solution to the poor quality of thumbnails generated by PHP. It has certain reference value. Friends in need can refer to it. I hope it can help everyone.

I recently created a forum. There should be a ranking on the homepage, showing a list of the top ten users with the most comments. The list has a thumbnail image of the latest uploaded work by the user. If the original image is used, the image will be too large. The home page loads too slowly, so you have to use the imagecopyresized function using the thumbnail image

. The display quality is very poor, as shown in

. Later, the effect of using imagecopyresampled changed significantly. The effect is as shown in the figure

Attached is the complete code:

100

101

102

103

104

/** 
* @name thum  缩略图函数 
* @param  sting  $img_name  图片路径 
* @param  int   $max_width 略图最大宽度 
* @param  int   $max_height 略图最大高度 
* @param  sting  $suffix 略图后缀(如"img_x.jpg"代表小图,"img_m.jpg"代表中图,"img_l.jpg"代表大图) 
* @return  void 
*/
function thum($img_name,$max_width,$max_height,$suffix){ 
    $img_infos=getimagesize($img_name); 
    $img_height=$img_infos[0];//图片高 
    $img_width=$img_infos[1];//图片宽 
    $img_extension=&#39;&#39;;//图片后缀名 
    switch($img_infos[2]){ 
      case 1: 
        $img_extension=&#39;gif&#39;; 
        break; 
      case 2: 
        $img_extension=&#39;jpeg&#39;; 
        break; 
      case 3: 
        $img_extension=&#39;png&#39;; 
        break; 
      default: 
        $img_extension=&#39;jpeg&#39;; 
        break; 
      } 
    $new_img_size=get_thum_size($img_width,$img_height,$max_width,$max_height);//新的图片尺寸 
  
    //print_r($new_img_size); 
    //die(&#39;test&#39;); 
    $img_func=&#39;&#39;;//函数名称 
    $img_handle=&#39;&#39;;//图片句柄 
    $thum_handle=&#39;&#39;;//略图图片句柄 
    switch($img_extension){ 
      case &#39;jpg&#39;: 
        $img_handle=imagecreatefromjpeg($img_name); 
        $img_func=&#39;imagejpeg&#39;; 
        break; 
      case &#39;jpeg&#39;: 
        $img_handle=imagecreatefromjpeg($img_name); 
        $img_func=&#39;imagejpeg&#39;; 
        break; 
      case &#39;png&#39;: 
        $img_handle=imagecreatefrompng($img_name); 
        $img_func=&#39;imagepng&#39;; 
        break; 
      case &#39;gif&#39;: 
        $img_handle=imagecreatefromgif($img_name); 
        $img_func=&#39;imagegif&#39;; 
        break; 
      default: 
        $img_handle=imagecreatefromjpeg($img_name); 
        $img_func=&#39;imagejpeg&#39;; 
        break; 
      } 
    /****/ 
    $quality=100;//图片质量 
    if($img_func===&#39;imagepng&#39; && (str_replace(&#39;.&#39;, &#39;&#39;, PHP_VERSION)>= 512)){//针对php版本大于5.12参数变化后的处理情况 
      $quality=9; 
      }  
    /****/
    $thum_handle=imagecreatetruecolor($new_img_size[&#39;height&#39;],$new_img_size[&#39;width&#39;]); 
    if(function_exists(&#39;imagecopyresampled&#39;)){ 
      imagecopyresampled($thum_handle,$img_handle, 0, 0, 0, 0,$new_img_size[&#39;height&#39;],$new_img_size[&#39;width&#39;],$img_height,$img_width); 
      }else{ 
        imagecopyresized($thum_handle,$img_handle, 0, 0, 0, 0,$new_img_size[&#39;height&#39;],$new_img_size[&#39;width&#39;],$img_height,$img_width); 
      } 
    call_user_func_array($img_func,array($thum_handle,get_thum_name($img_name,$suffix),$quality)); 
    imagedestroy($thum_handle);//清除句柄 
    imagedestroy($img_handle);//清除句柄 
  } 
/** 
* @name get_thum_size 获得缩略图的尺寸 
* @param  $width 图片宽 
* @param  $height 图片高 
* @param  $max_width 最大宽度 
* @param  $maxHeight 最大高度 
* @param  array $size; 
*/
function get_thum_size($width,$height,$max_width,$max_height){ 
  $now_width=$width;//现在的宽度 
  $now_height=$height;//现在的高度 
  $size=array(); 
  if($now_width>$max_width){//如果现在宽度大于最大宽度 
    $now_height*=number_format($max_width/$width,4); 
    $now_width= $max_width; 
    } 
  if($now_height>$max_height){//如果现在高度大于最大高度 
    $now_width*=number_format($max_height/$now_height,4); 
    $now_height=$max_height; 
    } 
  $size[&#39;width&#39;]=floor($now_width); 
  $size[&#39;height&#39;]=floor($now_height); 
  return $size; 
  } 
/** 
*@ name   get_thum_name 获得略图的名称(在大图基础加_x) 
*/
function get_thum_name($img_name,$suffix){ 
    $str=explode(&#39;#&#39;,$img_name); 
    $str1=explode(&#39;.&#39;,$str[1]); 
    return $str[0].&#39;_&#39;.$suffix.&#39;.&#39;.$str1[1]; 
  }

Copy after login

How do you learn it? Hurry up and give it a try.

Related recommendations:

php Use GD library to generate high-quality thumbnail image sample code

Detailed introduction to Bootstrap thumbnails

Detailed explanation of the solution to the blurry thumbnail distortion of DedeCMS

The above is the detailed content of Solution to the poor quality of thumbnails generated by php. For more information, please follow other related articles on the PHP Chinese website!