Auto Resize Images with MODx (Plugin)

<img src="someimage.png" width="200" height="50" />

/*
*	Auto Document Image Resizer (Resampler) for MODx
*	Retrives all document (page) images prior to rendering. 
*	If the image dimensions do not match it will resample a new image to fit the image attributes specified in the HTML.
*	This aims to prevent the pixelated and distorted output that large images heavily scaled result in.
*	It will also improve on load time.
 
*	Resampled images are cached in the /assets/cache/ directory.
*	Requires the PHP GD Graphics Library to process the images.
*
*	Version 0.2 - Test version - Quicky written and limited testing
*	Licensed under LGPL.
*
*	Author: Daniel Gibbs
*	Website: www.danielgibbs.net
*
*	Inspired by the Auto Image Resizer by Nathan Hill and Adam Crownoble. 
*	header('Content-type: image/jpeg');
*/
 
# ini_set('display_errors', '1');
# ini_set('error_reporting ', 'E_ALL | E_STRICT');
ini_set("memory_limit", "256M");
 
$quality = 100; 	// The image quality (0-100)
 
if($modx->Event->name == "OnWebPagePrerender") {
	$output = $modx->documentOutput;
	$dom = new DOMDocument();
	@$dom->loadHTML($output);
 
	$images = $dom->getElementsByTagName("img");
 
	foreach($images as $image) {
		// Get DOM attributes
		$width = $image->getAttribute("width");
		$height = $image->getAttribute("height");
		$style = $image->getAttribute("style");
		$source = $image->getAttribute("src");
 
		// File information
		$filename = basename($source);
		$fileinfo = pathinfo($source);
		$filetype = $fileinfo['extension'];
 
		$cachepath = $modx->config['base_path']."assets/cache/";
		$cachepath_url = $modx->config['base_url']."assets/cache/";
 
		// Find width and/or height from inline style
		if ($style) {
				preg_match("/width:(.*\w)px\;/", $style, $return);
				if($return[1]) $width = cleanValue($return[1]);
 
				preg_match("/height:(.*\w)px\;/", $style, $return);
				if($return[1]) $height = cleanValue($return[1]);
		}
 
		// Check the values valid (i.e. pixels not percentages) and move on
		if (is_numeric($width) && is_numeric($height) && !file_exists($cachepath.$filename)) {
			$path = $modx->config['base_path'].$source;
 
 			$fh = @fopen($path, "r");
 
			if ($fh !== false) {
				fclose($fh);
 
				// Get information on the original image 
				list($originalwidth, $originalheight) = getimagesize($path);
 
				// Check the images are different in size and doesn't already exist in the cache
				if ($originalwidth != $width || $originalheight != $height && !file_exists($cachepath.$filename)) {
						$imageprocess = imagecreatetruecolor($width, $height);
 
						switch (strtolower($filetype)) {
							case "jpg": $canvas = imagecreatefromjpeg($path); 
								break;
							case "jpeg": $canvas = imagecreatefromjpeg($path); 
								break;
							case "gif": $canvas = imagecreatefromgif($path); 
								break;
							case "png": $canvas = imagecreatefrompng($path); 
								break;
						}
 
						imagecopyresampled($imageprocess, $canvas, 0, 0, 0, 0, $width, $height, $originalwidth, $originalheight);
 
						// The output path
						$writepath = $cachepath.$filename;
 
						// Save new file
						switch (strtolower($filetype)) {
							case "jpg": imagejpeg($imageprocess, $writepath, $quality); 
								break;
							case "jpeg": imagejpeg($imageprocess, $writepath, $quality); 
								break;
							case "gif": imagegif($imageprocess, $writepath, $quality); 
								break;
							case "png": imagepng($imageprocess, $writepath, $quality); 
								break;
						}
 
						// Destroy the processed image
						imagedestroy($imageprocess);
 
 
						// Replace the src to the new image location
						$image->setAttribute("src", $cachepath_url.$filename);
					}
			}
		}
 
		// Image exists in cache, replace src attribute
        if (is_numeric($width) && is_numeric($height) && file_exists($cachepath.$filename)) {
        	$image->setAttribute("src", $cachepath_url.$filename);
		}
	}
 
	$modx->documentOutput = $dom->saveHTML();
}
 
function cleanValue($value) {
		$return = trim(str_replace("px", "", $value));
		return $return;
}
 
// FIN