Simple image resizer class

SimpleImage.php

<?php
/*
* File: SimpleImage.php
* Author: Simon Jarvis
* Modified by: Juanita Vyatri (@vyatri)
* Copyright: 2006 Simon Jarvis
* Date: 08/11/06
* Last modified: 08/11/10
* 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,$height,$forcesize='n') {
   
      /* optional. if file is smaller, do not resize. */
	  if ($forcesize == 'n') {
		  if ($width > $this->getWidth() && $height > $this->getHeight()){
			  $width = $this->getWidth();
			  $height = $this->getHeight();
		  }
	  }
   
      $new_image = imagecreatetruecolor($width, $height);
      //imagecopyresampled($new_image, $this->image, 0, 0, 0, 0, $width, $height, $this->getWidth(), $this->getHeight());
	  /* Check if this image is PNG or GIF, then set if Transparent*/  
	  if(($this->image_type == IMAGETYPE_GIF) OR ($this->image_type==IMAGETYPE_PNG)){
		  imagealphablending($new_image, false);
		  imagesavealpha($new_image,true);
		  $transparent = imagecolorallocatealpha($new_image, 255, 255, 255, 127);
		  imagefilledrectangle($new_image, 0, 0, $width, $height, $transparent);
	  }
	  imagecopyresampled($new_image, $this->image, 0, 0, 0, 0, $width, $height, $this->getWidth(), $this->getHeight());
	 
      $this->image = $new_image;   
   }      
}
?>

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

load('picture.jpg'); $image->resize(250,400); $image->save('picture2.jpg'); ?>

Example to resize and change quality to 80%, and format from png to jpg

load('picture.png'); $image->resize(250,400); $image->save('picture2.jpg','IMAGETYPE_JPEG',80); // quality change only allowed for JPEG saving ?>

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.

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

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

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

load('picture.jpg'); $image->resizeToWidth(150); $image->output(); ?>

The following example will resize and save an image which has been uploaded via a form

load($_FILES['uploaded_image']['tmp_name']); $image->resizeToWidth(150); $image->output(); } else { ?>