Darkbyte Library

<?php
/***************************************************************************
 * class.gzipcontent.php
 * ---------------------
 * Author: Alan Doyle (alan.doyle@darkbyte.com)
 * Copyright: (c) 2000 - 2005 Darkbyte Software
 * Release Version: 1.2
 * Date Started: 1st October 2002
 *
 * A simple PHP Class to Gzip Encode your webpages and to set the mime type to
 * application/xhtml+xml if it's supported.
 *
 ***************************************************************************
 *
 *   class.gzipcontent.php 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.
 *
 *   class.gzipcontent.php 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.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with class.gzipcontent.php; if not, write to the Free Software
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 *
 **************************************************************************/
 
class gzipcontent
{
	var $name	= "Darkbyte Software Gzip Contents";
	var $version = "1.2";
	var $url	 = "http://darkbyte.com/library.php/PHP/gzipcontents";
 
	var $size;     // size of the uncompressed content
	var $compsize; // size of the compressed content
	var $level;    // Compression level
	var $encoding; // Encoding type
	var $crc;      // crc of the output
	var $mime;     // mime type to use for encoding
	var $charset;  // Output charset
	var $override; // Used to override Mime detection
 
	/*
	 * gzipcontent constructor - setup gzip encoding variables and outputs the
	 *                           corresponding header.
	 *
	 * Note: The arguments are optionial.
	 *
	 * You can specify one of the following for the first argument:
	 *	0:	No compression ... useful for debugging
	 *	1:	Min compression
	 *	...
	 *	9:	Max compression
	 *
	 * You can specify any character set using the second argument
	 *  Default is iso-8859-1
	 *
	 * The third argument is used to override Mime detection to use "text/html"
	 *
	 */
	function gzipcontent($level = 3, $charset="iso-8859-1", $override = false )
	{
		if (!function_exists('gzcompress'))
		{
			trigger_error('gzcompress not found, zlib needs to be installed for gzip_content', E_USER_WARNING);
			return;
		}
		if (!function_exists('crc32'))
		{
			trigger_error('crc32() not found, PHP >= 4.0.1 needed for gzip_content', E_USER_WARNING);
			return;
		}
 
		if (headers_sent())
			return;
 
		if (connection_status() !== 0)
			return;
 
		$this->charset  = $charset;
		$this->level	= $level;
		$this->override = $override;
		$this->mime	 = $this->getmime();
		$this->encoding = $this->accepted();
	}
 
	function debuginfo()
	{
		print "<!-- Charset  : " . $this->charset . " -->\n";
		print "<!-- Level	: " . $this->level . " -->\n";
		print "<!-- Override : " . ($this->override ? "Enabled" : "Disabled") . " -->\n";
		print "<!-- Mime	 : " . $this->mime . " -->\n";
		print "<!-- Encoding : " . $this->encoding . " -->\n";
	}
 
	function compress( $contents )
	{
		$encoded = $this->name . " v" . $this->version . " [" . $this->url . "]";
		$skip = false;
 
		if (!is_string($contents))
			$contents = ob_get_contents();
 
		if ($contents === false)
			return;
 
		if($this->mime === "text/html")
			$contents = ereg_replace(" />", ">", $contents);
 
		$contents = ereg_replace("</head>", "</head>\n<!-- Compressed with " . $encoded . " -->", $contents);
 
		if ($this->level === 0 )
			$skip = true;
 
		if ($this->encoding === false )
			$skip = true;
 
		if( $skip === false )
		{
			// OK Let's compress this file
			$gzdata = "\x1f\x8b\x08\x00\x00\x00\x00\x00"; // gzip header
			$size = strlen($contents);
			$crc = crc32($contents);
			$gzdata .= gzcompress($contents, $this->level);
			$gzdata = substr($gzdata, 0, strlen($gzdata) - 4);
			$gzdata .= pack("V",$crc) . pack("V", $size);
 
			$this->size   = $size;
			$this->crc	= $crc;
			$this->compsize = strlen($gzdata);
 
			ob_end_clean();
 
			Header('Content-Type: ' . $this->mime . ';charset=' . $this->charset);
			Header('Content-Encoding: ' . $this->encoding);
			Header('Vary: Accept-Encoding');
			Header('Content-Length: ' . strlen($gzdata));
			Header('X-Content-Encoded-By: ' . $encoded );
			echo $gzdata;
		}
		else
		{
			ob_end_clean();
			// No compression, simply send headers and away we go
			Header('Content-Type: ' . $this->mime . ';charset=' . $this->charset);
			echo $contents;
		}
 
	}
 
	function getmime()
	{
		$mime	= "text/html";
		$charset = "iso-8859-1";
 
		if(stristr($_SERVER["HTTP_ACCEPT"],"application/xhtml+xml"))
		{
			if(preg_match("/application\/xhtml\+xml;q=0(\.[1-9]+)/i", $_SERVER["HTTP_ACCEPT"], $matches))
			{
				$xhtml_q = $matches[1];
				if(preg_match("/text\/html;q=0(\.[1-9]+)/i", $_SERVER["HTTP_ACCEPT"], $matches))
				{
					$html_q = $matches[1];
					if($xhtml_q >= $html_q)
						$mime = "application/xhtml+xml";
				}
			}
			else
				$mime = "application/xhtml+xml";
		}
 
		// special check for the W3C_Validator
		if (stristr($_SERVER["HTTP_USER_AGENT"],"W3C_Validator"))
			$mime = "application/xhtml+xml";
 
		// Override the about and force "text/html"
		if( $this->override === true )
			$mime = "text/html";
 
		return $mime;
	}
 
	function accepted()
	{
		if (strpos($_SERVER["HTTP_ACCEPT_ENCODING"], 'gzip') === false)
			return false;
		if (strpos($_SERVER["HTTP_ACCEPT_ENCODING"], 'x-gzip') === false)
			$encoding = 'gzip';
		else
			$encoding = 'x-gzip';
		// Test file type.
		$magic = substr(ob_get_contents(),0,4);
		if (substr($magic,0,2) === '^_')
			$encoding = false;   // gzip data
		else if (substr($magic,0,2) === "\xFF\xD8")
			$encoding = false;   // jpeg images
		else if (substr($magic,0,2) === 'PK')
			$encoding = false;   // pkzip file
		else if (substr($magic,0,3) === 'GIF')
			$encoding = false;   // gif images
		else if (substr($magic,0,3) === 'FWS')
			$encoding = false;   // Shockwave Flash
		else if (substr($magic,0,4) === "\x89PNG")
			$encoding = false;   // png images
 
		return $encoding;
	}
}
?>