SWF head reader

<?php
/**
* Flash Header reader
* Alessandro Crugnola (sephiroth)
* [email protected]
* http://www.sephiroth.it
* 
* Read the SWF header informations and return an 
* associative array with the property of the SWF File
*
* @param input string file
* @returns array
*
*
* **** HOW TO USE *****
* -------------------------------------
* $f = new FlashHeader("flash.swf");
* $result = $f->getimagesize();
* print_r($result);
* -------------------------------------
*
*/
class FlashHeader{
	var $version;
	var $filetype;
	var $bitpos;
	var $cur;
	var $pos;
	var $rect;
	var $framerate;
	var $length;
	var $compression = 0;
	var $point = 0;
	var $isValid = 0;
	/**
	* @method FlashHeader 
	* @type constructor 
	* @param string file
	*/
	function FlashHeader($buffer){
        $this->buffer = $buffer;
        $fp = @fopen($this->buffer,"rb");
        $head = @fread($fp, 3);
		if($head == "CWS"){
			/* zlib */
			fseek($fp,0);
			$data = fread($fp,8);
			$_data = gzuncompress(fread($fp, filesize($buffer)));
			$data = $data . $_data;
			$this->data = $data;
			$this->compression = 1;
			$this->isValid = 1;
		} else if ($head == "FWS"){
			fseek($fp,0);
			$this->data = fread($fp, filesize($buffer));
			$this->isValid = 1;
		} else {
			$this->isValid = 0;
		}
		@fclose($fp);
	}
	
	/**
	* @method getimagesize
	* @type public
	* @description read the file informations
	*/
	function getimagesize(){
		if(!$this->isValid){
			return false;
		}
        $this->filetype = $this->read(3);
        $this->version =  $this->readbyte();
        $l = $this->read(4);
        $this->filelength = filesize($this->buffer);
        $this->rect = $this->readRect();
        $this->framerate = unpack('vrate',$this->read(2));
        $this->framerate = $this->framerate['rate']/256;
        $this->framecount = $this->readshort();
        return array(	
						"zlib-compression"=> $this->compression, 
        				"fileType" => $this->filetype, 
        				"version" => $this->version,
        				"fileSize" => $this->filelength,
        				"frameRate" => $this->framerate,
        				"frameCount" => $this->framecount,
        				"movieSize" => $this->rect
        			);
	}
	
	/* read */
	function read($n){
		$ret = substr($this->data, $this->point, $this->point + $n);
		$this->point += $n;
		return $ret;
	}	
	
	/* read short */
    function readshort(){
        $pack = unpack('vshort',$this->read(2));
        return $pack['short'];
	}
	
	/* read byte */
    function readByte(){
        $ret = unpack("Cbyte",$this->read(1));
		return $ret['byte'];
	}
	/* read Rect */
    function readRect(){
        $this->begin();
        $l = $this->readbits(5);
        $xmin = $this->readbits($l)/20;
        $xmax = $this->readbits($l)/20;
        $ymin = $this->readbits($l)/20;
        $ymax = $this->readbits($l)/20;
        $rect = new Rect($xmax, $ymax);
        return $rect->__str__();
	}
	/* incpos */
    function incpos(){
        $this->pos += 1;
        if($this->pos>8){
            $this->pos = 1;
            $this->cur = $this->readbyte();
		}
	}	
	
	
	/* readbits */
    function readbits($nbits){
        $n = 0;
        $r = 0;
        while($n < $nbits){
            $r = ($r<<1) + $this->getbits($this->pos);
            $this->incpos();
            $n += 1;
		}
        return $r;
	}
	
	/* getbits */
    function getbits($n){
        return ($this->cur>>(8-$n))&1;
	}
	
	/* begin */
    function begin(){
        $this->cur = $this->readbyte();
        $this->pos = 1;
	}
	
}

/**
* class Rect
* store the size values into an associative array
*/
class Rect{
    function Rect($x2,$y2){
        $this->xmax = $x2;
        $this->ymax = $y2;
        $this->value = $this->__str__();
	}
    function __str__(){
		$ret = array($this->xmax, $this->ymax);
        $ret["width"] = $this->xmax;
        $ret["height"] = $this->ymax;
        return $ret;
	}
}
/* end */
?>