This class is useful to create mirror images using the GD Library. You just need to set the source path of the image (URL or local path) and the folder where the new image should be saved. If the latter is not specified the image will output without being saved. This is useful if you need to generate mirror images ‘on the fly’.

Here’s the source code (I will explain you how it works below):

<?php
/*
--------------------------------------------------------------------------------------------
Credits: Bit Repository
Source URL: http://www.bitrepository.com/
--------------------------------------------------------------------------------------------
*/

/* Image Mirror Class */

class Image_Mirror {

var $source_image;
var $new_image_name;
var $save_to_folder;

function make_mirror_image($flip = 1)
{
$info = GetImageSize($this->source_image);

if(empty($info)) {
	exit("The file from the requested path doesn't see to be an image");
}

$width = $info[0];
$height = $info[1];

$mime = $info['mime'];

// What sort of image?

$type = substr(strrchr($mime, '/'), 1);

switch ($type)
{
case 'jpeg':
    $image_create_func = 'ImageCreateFromJPEG';
    $image_save_func = 'ImageJPEG';
	$new_image_ext = 'jpg';
	$quality = 100; // best quality
    break;

case 'png':
    $image_create_func = 'ImageCreateFromPNG';
    $image_save_func = 'ImagePNG';
	$new_image_ext = 'png';
	$quality = 0; // no compression
    break;

case 'bmp':
    $image_create_func = 'ImageCreateFromBMP';
    $image_save_func = 'ImageBMP';
	$new_image_ext = 'bmp';
    break;

case 'gif':
    $image_create_func = 'ImageCreateFromGIF';
    $image_save_func = 'ImageGIF';
	$new_image_ext = 'gif';
    break;

case 'vnd.wap.wbmp':
    $image_create_func = 'ImageCreateFromWBMP';
    $image_save_func = 'ImageWBMP';
	$new_image_ext = 'bmp';
    break;

case 'xbm':
    $image_create_func = 'ImageCreateFromXBM';
    $image_save_func = 'ImageXBM';
	$new_image_ext = 'xbm';
    break;

default:
	$image_create_func = 'ImageCreateFromJPEG';
    $image_save_func = 'ImageJPEG';
	$new_image_ext = 'jpg';
}

// Source Image
$image = $image_create_func($this->source_image);

$new_image = ImageCreateTrueColor($width, $height);

// Set a White & Transparent Background Color (PHP 4 >= 4.3.2, PHP 5)
$bg = ImageColorAllocateAlpha($new_image, 255, 255, 255, 127);
ImageFill($new_image, 0, 0 , $bg);

if($flip == 1)
{
   $dst_y = 0;
   $src_y = 0;

   $coordinate = ($width - 1);

   foreach(range($width, 0) as $range)
   {
   $src_x = $range;
   $dst_x = $coordinate - $range;

   ImageCopy($new_image, $image, $dst_x, $dst_y, $src_x, $src_y, 1, $height);
   }
}
elseif($flip == 2)
{
   $dst_x = 0;
   $src_x = 0;

   $coordinate = ($height - 1);

   foreach(range($height, 0) as $range)
   {
   $src_y = $range;
   $dst_y = $coordinate - $range;

   ImageCopy($new_image, $image, $dst_x, $dst_y, $src_x, $src_y, $width, 1);
   }
}

if(isSet($this->save_to_folder))
		{
	       if($this->new_image_name)
	       {
	       $new_name = $this->new_image_name.'.'.$new_image_ext;
	       }
	       else
	       {
$basename = basename($this->source_image);
$new_name = $this->new_image_name($basename).'_mirror.'.$new_image_ext;
	       }

		$save_path = $this->save_to_folder.$new_name;
		}
		else
		{
		/* Set the right header for the image */
		   header("Content-Type: ".$mime);

		   $save_path = '';
		}

// Show/Save image 

if(isSet($quality))
	{
	$process = $image_save_func($new_image, $save_path, $quality);
	}
	else
	{
	$process = $save_path ? $image_save_func($new_image, $save_path) : $image_save_func($new_image);
	}

return array('result' => $process, 'new_file_path' => $save_path);
	}

function new_image_name($filename)
{
		$ext = strrchr($filename, ".");

	if($ext)
	{
	$strlen = strlen($ext);
	$filename = basename(substr($filename, 0, -$strlen));
	}

	$string = trim($filename);
	$string = strtolower($string);
	$string = trim(ereg_replace("[^ A-Za-z0-9_]", " ", $string));
	$string = ereg_replace("[ \t\n\r]+", "_", $string);
	$string = str_replace(" ", '_', $string);
	$string = ereg_replace("[ _]+", "_", $string);

	return $string;
}

}
?>

How it works?

First, we need to get the width, height & mime type of the source image by using GetImageSize(). The latter is used to determine the function that creates a new image from our file/URL. For effectiveness, we will use the concept of variable functions. For example, if the image is a PNG, $image_create_func will be equal with