Resizing images with PHP（Php生成缩略图）

<?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;
    }      
 
}

<?php
    include('SimpleImage.php');
    $image = new SimpleImage();
    $image->load('picture.jpg');
    $image->resize(250,400);
    $image->save('picture2.jpg');

include('SimpleImage.php');
$image = new SimpleImage();
$image->load('picture.jpg');
$image->resizeToWidth(250);
$image->save('picture2.jpg');

include('SimpleImage.php');
$image = new SimpleImage();
$image->load('picture.jpg');
$image->scale(50);
$image->save('picture2.jpg');

include('SimpleImage.php');
$image = new SimpleImage();
$image->load('picture.jpg');
$image->resizeToHeight(500);
$image->save('picture2.jpg');
$image->resizeToHeight(200);
$image->save('picture3.jpg');

header('Content-Type: image/jpeg');
include('SimpleImage.php');
$image = new SimpleImage();
$image->load('picture.jpg');
$image->resizeToWidth(150);
$image->output();

<?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
   }
?>