Watermark PHP

watermark.html

<img src="watermark.php?watermark=watermark.png&src=test.jpg" />

watermark.php

<?php

	// check to see if the files exist
	if(!file_exists($_GET['src'])){
		die('Image does not exist.');
	}
	if(!file_exists($_GET['watermark'])){
		die('Watermark does not exist.');
	}
	
	$src = $_GET['src'];
	
	// create the proper image from the filetype	
	switch(end(explode('.', $src))){
		case 'gif':
			$image = imagecreatefromgif($src);
			break;
		case 'jpg':
		case 'jpeg':
			$image = imagecreatefromjpeg($src);
			break;
		case 'png':
			$image = imagecreatefrompng($src);
			break;
		default:
			die('Not a valid image type.');
	}
	
	$watermark_src = $_GET['watermark'];
	
	// create the proper image from the watermark filetype
	switch(end(explode('.', $watermark_src))){
		case 'png':
			$watermark = imagecreatefrompng($watermark_src);
			break;
		case 'gif':
			$watermark = imagecreatefromgif($watermark_src);
		default:
			die('Not a valid watermark image.');
	}
	
	// image size
	$image_width = imagesx($image);
	$image_height = imagesy($image);
	
	// watermark size
	$watermark_width = imagesx($watermark);
	$watermark_height = imagesy($watermark);
	
	// position the watermark
	
	// center center
	$start_width = (($image_width - $watermark_width) / 2);
	$start_height = (($image_height - $watermark_height) / 2);
	
	// top left
	//$start_width = 0;
	//$start_height = 0;
	
	// bottom right
	//$start_width = ($image_width - $watermark_width);
	//$start_height = ($image_height - $watermark_height);
	
	// create the image
	imagecopy($image, $watermark, $start_width, $start_height, 0, 0, $watermark_width, $watermark_height);
	
	// and display it
	header('content-type: image/jpeg');
	imagejpeg($image);
	
	// cleanup
	imagedestroy($image);
	imagedestroy($watermark);