php实现在服务器端调整图片大小的方法

本文实例讲述了php实现在服务器端调整图片大小的方法。分享给大家供大家参考。具体分析如下：

在服务器端完成图片大小的调整，会比在浏览器的处理有很多的好处。
本文介绍了php如何在服务器端调整图片大小。

代码包括两部分：

① imageresizer() is used to process the image
② loadimage() inserts the image url in a simpler format

<?php
 function imageresizer($url, $width, $height) {
  header('content-type: image/jpeg');
  list($width_orig, $height_orig) = getimagesize($url);
  $ratio_orig = $width_orig/$height_orig;
  if ($width/$height > $ratio_orig) {
   $width = $height*$ratio_orig;
  } else {
   $height = $width/$ratio_orig;
  }
  // this resamples the image
  $image_p = imagecreatetruecolor($width, $height);
  $image = imagecreatefromjpeg($url);
  imagecopyresampled($image_p, $image, 0, 0, 0, 0, $width, $height, $width_orig, $height_orig);
  // output the image
  imagejpeg($image_p, null, 100);
 }
 //works with both post and get
 $method = $_server['request_method'];
 if ($method == 'get') {
  imageresize($_get['url'], $_get['w'], $_get['h']);
  } elseif ($method == 'post') {
  imageresize($_post['url'], $_post['w'], $_post['h']);
  }
 // makes the process simpler
 function loadimage($url, $width, $height){
  echo 'image.php?url=', urlencode($url) ,
  '&w=',$width,
  '&h=',$height;
 }
?>

用法：

//above code would be in a file called image.php.
//images would be displayed like this:
<img src="<?php loadimage('image.jpg', 50, 50) ?>" alt="" />

希望本文所述对大家的php程序设计有所帮助。