<?php
/*
* File: SimpleImage.php
* Author: Simon Jarvis
* Copyright: 2006 Simon Jarvis
* Date: 08/11/06
* Link: http://www.white-hat-web-design.co.uk/articles/php-image-resizing.php
* 
* This program is free software; you can redistribute it and/or 
* modify it under the terms of the GNU General Public License 
* as published by the Free Software Foundation; either version 2 
* of the License, or (at your option) any later version.
* 
* This program is distributed in the hope that it will be useful, 
* but WITHOUT ANY WARRANTY; without even the implied warranty of 
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 
* GNU General Public License for more details: 
* http://www.gnu.org/licenses/gpl.html
*
*/
 
class SimpleImage {
 
   var $image;
   var $image_type;
 
   function load($filename) {
      $image_info = getimagesize($filename);
      $this->image_type = $image_info[2];
      if( $this->image_type == IMAGETYPE_JPEG ) {
         $this->image = imagecreatefromjpeg($filename);
      } elseif( $this->image_type == IMAGETYPE_GIF ) {
         $this->image = imagecreatefromgif($filename);
      } elseif( $this->image_type == IMAGETYPE_PNG ) {
         $this->image = imagecreatefrompng($filename);
      }
   }
   function save($filename, $image_type=IMAGETYPE_JPEG, $compression=75, $permissions=null) {
      if( $image_type == IMAGETYPE_JPEG ) {
         imagejpeg($this->image,$filename,$compression);
      } elseif( $image_type == IMAGETYPE_GIF ) {
         imagegif($this->image,$filename);         
      } elseif( $image_type == IMAGETYPE_PNG ) {
         imagepng($this->image,$filename);
      }   
      if( $permissions != null) {
         chmod($filename,$permissions);
      }
   }
   function output($image_type=IMAGETYPE_JPEG) {
      if( $image_type == IMAGETYPE_JPEG ) {
         imagejpeg($this->image);
      } elseif( $image_type == IMAGETYPE_GIF ) {
         imagegif($this->image);         
      } elseif( $image_type == IMAGETYPE_PNG ) {
         imagepng($this->image);
      }   
   }
   function getWidth() {
      return imagesx($this->image);
   }
   function getHeight() {
      return imagesy($this->image);
   }
   function resizeToHeight($height) {
      $ratio = $height / $this->getHeight();
      $width = $this->getWidth() * $ratio;
      $this->resize($width,$height);
   }
   function resizeToWidth($width) {
      $ratio = $width / $this->getWidth();
      $height = $this->getheight() * $ratio;
      $this->resize($width,$height);
   }
   function scale($scale) {
      $width = $this->getWidth() * $scale/100;
      $height = $this->getheight() * $scale/100; 
      $this->resize($width,$height);
   }
   function resize($width,$height) {
      $new_image = imagecreatetruecolor($width, $height);
      imagecopyresampled($new_image, $this->image, 0, 0, 0, 0, $width, $height, $this->getWidth(), $this->getHeight());
      $this->image = $new_image;   
   }      
}
?>
 
 
Save the above file as SimpleImage.php and take a look at the following examples of how to use the script.
 
The first example below will load a file named picture.jpg resize it to 250 pixels wide and 400 pixels high and resave it as picture2.jpg
 
<?php
   include('SimpleImage.php');
   $image = new SimpleImage();
   $image->load('picture.jpg');
   $image->resize(250,400);
   $image->save('picture2.jpg');
?>
If you want to resize to a specifed width but keep the dimensions ratio the same then the script can work out the required height for you, just use the resizeToWidth function.
 
<?php
   include('SimpleImage.php');
   $image = new SimpleImage();
   $image->load('picture.jpg');
   $image->resizeToWidth(250);
   $image->save('picture2.jpg');
?>
You may wish to scale an image to a specified percentage like the following which will resize the image to 50% of its original width and height
 
<?php
   include('SimpleImage.php');
   $image = new SimpleImage();
   $image->load('picture.jpg');
   $image->scale(50);
   $image->save('picture2.jpg');
?>
You can of course do more than one thing at once. The following example will create two new images with heights of 200 pixels and 500 pixels
 
<?php
   include('SimpleImage.php');
   $image = new SimpleImage();
   $image->load('picture.jpg');
   $image->resizeToHeight(500);
   $image->save('picture2.jpg');
   $image->resizeToHeight(200);
   $image->save('picture3.jpg');
?>
The output function lets you output the image straight to the browser without having to save the file. Its useful for on the fly thumbnail generation
 
<?php
   header('Content-Type: image/jpeg');
   include('SimpleImage.php');
   $image = new SimpleImage();
   $image->load('picture.jpg');
   $image->resizeToWidth(150);
   $image->output();
?>
The following example will resize and save an image which has been uploaded via a form
 
<?php
   if( isset($_POST['submit']) ) {
      include('SimpleImage.php');
      $image = new SimpleImage();
      $image->load($_FILES['uploaded_image']['tmp_name']);
      $image->resizeToWidth(150);
      $image->output();
   } else {
?>
   <form action="upload.php" method="post" enctype="multipart/form-data">
      <input type="file" name="uploaded_image" />
      <input type="submit" name="submit" value="Upload" />
   </form>
<?php
   }
?>