amfinputstream.php

实现flash的饼图投票

<?php
/*
	AMFInputStream class built to handle getting the binary data from the raw input stream.
	这个类处理未加工的input流,使之变成二进制的数据.
*/
class AMFInputStream
{
	// holder（保持者） for our raw data
	var $raw_data;
	// the seek（寻求） head of our input stream
	var $current_byte;
	// the total size of the stream,流的总大小
	var $content_length;

	var $byteorder;
	
	/*
		AMFInputStream constructor(构造器)
		arguments	$rd	raw data stream
	*/
	function AMFInputStream(&$rd)
	{
		$this->current_byte=0;
		// store the stream in this object
		$this->raw_data = &$rd;
		// grab the total length of this stream
		$this->content_length = strlen($this->raw_data);
		// determine the multi-byte ordering of this machine
		// temporarily pack 1
		$tmp = pack("d", 1);
		// if the bytes are not reversed
		if ($tmp=="\0\0\0\0\0\0\360\77") {
			$this->byteorder = 'big-endian';
		}
		// the bytes are reversed
		else if ($tmp == "\77\360\0\0\0\0\0\0")	{
			$this->byteorder = 'little-endian';
		}
	}
	

	// returns a single（单一的） byte（n.字节, 8位元组） value.
	function readByte()
	{
		// return the next byte
		return ord($this->raw_data[$this->current_byte++]);
	}
	
	// returns the value of 2 bytes
	function readInt() 
	{
		// read the next 2 bytes, shift and add
		return  ((ord($this->raw_data[$this->current_byte++]) << 8) | 
				 ord($this->raw_data[$this->current_byte++]));
	}
	
	// returns the value of 4 bytes
	function readLong() 
	{
		// read the next 4 bytes, shift and add
		return ((ord($this->raw_data[$this->current_byte++]) << 24) | 
				(ord($this->raw_data[$this->current_byte++]) << 16) |
				(ord($this->raw_data[$this->current_byte++]) << 8) |
				 ord($this->raw_data[$this->current_byte++]));
	}
	
	// returns the value of 8 bytes
	function readDouble()
	{
		if ($this->byteorder == "big-endian") {
			// container to store the reversed bytes
			$invertedBytes = "";
			// create a loop with a backwards index
			for($i = 7 ; $i >= 0 ; $i--) {
				// grab the bytes in reverse order from the backwards index
				$invertedBytes .= $this->raw_data[$this->current_byte+$i];
			}
			// move the seek head forward 8 bytes
			$this->current_byte += 8;
		} else {
			// container to store the bytes
			$invertedBytes = "";
			// create a loop with a forwards index
			for($i = 0 ; $i < 8 ; $i++)	{
				// grab the bytes in forward order
				$invertedBytes .= $this->raw_data[$this->current_byte+$i];
			}
			// move the seek head forward
			$this->current_byte += 8;
		}
		// unpack the bytes
		$zz = unpack("dflt", $invertedBytes);
		// return the number from the associative array
		return $zz['flt'];
	}
	
	
    // returns a UTF string 支持中文，需要修改下面两函数
    function readUTF()
    {
        // get the length of the string (1st 2 bytes)
        $length = $this->readInt();
        // grab the string

		$val = substr($this->raw_data, $this->current_byte, $length);
        //$val = utf8_decode(substr($this->raw_data, $this->current_byte, $length));
		//$val = iconv("UTF-8","GB2312",substr($this->raw_data, $this->current_byte, $length));
		 //$val = mb_convert_encoding((substr($this->raw_data, $this->current_byte, $length)),"EUC-CN","UTF-8");
        // move the seek head to the end of the string
        $this->current_byte += $length;
        // return the string
        return $val;
    }
	
	// returns a UTF string with a LONG representing the length
	function readLongUTF()
	{
		// get the length of the string (1st 4 bytes)
		$length = $this->readLong();
		// grab the string
		$val = substr($this->raw_data, $this->current_byte, $length);
		//$val = iconv("UTF-8","GB2312",substr($this->raw_data, $this->current_byte, $length));
		//$val = utf8_decode(substr($this->raw_data, $this->current_byte, $length));
		//$val = mb_convert_encoding((substr($this->raw_data, $this->current_byte, $length)),"EUC-CN","UTF-8");
		// move the seek head to the end of the string
		$this->current_byte += $length;
		// return the string
		return $val;
	}
}
?>