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<?php
/*
* Module written/ported by Xavier Noguer <xnoguer@rezebra.com>
*
* The majority of this is _NOT_ my code. I simply ported it from the
* PERL Spreadsheet::WriteExcel module.
*
* The author of the Spreadsheet::WriteExcel module is John McNamara
* <jmcnamara@cpan.org>
*
* I _DO_ maintain this code, and John McNamara has nothing to do with the
* porting of this code to PHP. Any questions directly related to this
* class library should be directed to me.
*
* License Information:
*
* Spreadsheet::WriteExcel: A library for generating Excel Spreadsheets
* Copyright (C) 2002 Xavier Noguer xnoguer@rezebra.com
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
/**
* Class for writing Excel BIFF records.
*
* From "MICROSOFT EXCEL BINARY FILE FORMAT" by Mark O'Brien (Microsoft Corporation):
*
* BIFF (BInary File Format) is the file format in which Excel documents are
* saved on disk. A BIFF file is a complete description of an Excel document.
* BIFF files consist of sequences of variable-length records. There are many
* different types of BIFF records. For example, one record type describes a
* formula entered into a cell; one describes the size and location of a
* window into a document; another describes a picture format.
*
* @author Xavier Noguer <xnoguer@rezebra.com>
* @package Spreadsheet_WriteExcel
*/
class BIFFWriter
{
var $_BIFF_version = 0x0500;
/**
* Constructor
*
* @access public
*/
function BIFFwriter()
{
// The byte order of this architecture. 0 => little endian, 1 => big endian
$this->_byte_order = '';
// The string containing the data of the BIFF stream
$this->_data = '';
// Should be the same as strlen($this->_data)
$this->_datasize = 0;
// The maximun length for a BIFF record. See _add_continue()
$this->_limit = 2080;
// Set the byte order
$this->_set_byte_order();
}
/**
* Determine the byte order and store it as class data to avoid
* recalculating it for each call to new().
*
* @access private
*/
function _set_byte_order()
{
if ($this->_byte_order == '')
{
// Check if "pack" gives the required IEEE 64bit float
$teststr = pack("d", 1.2345);
$number = pack("C8", 0x8D, 0x97, 0x6E, 0x12, 0x83, 0xC0, 0xF3, 0x3F);
if ($number == $teststr) {
$byte_order = 0; // Little Endian
}
elseif ($number == strrev($teststr)){
$byte_order = 1; // Big Endian
}
else {
// Give up. I'll fix this in a later version.
die("Required floating point format not supported ".
"on this platform. See the portability section ".
"of the documentation."
);
}
}
$this->_byte_order = $byte_order;
}
/**
* General storage function
*
* @param string $data binary data to prepend
* @access private
*/
function _prepend($data)
{
if (strlen($data) > $this->_limit) {
$data = $this->_add_continue($data);
}
$this->_data = $data.$this->_data;
$this->_datasize += strlen($data);
}
/**
* General storage function
*
* @param string $data binary data to append
* @access private
*/
function _append($data)
{
if (strlen($data) > $this->_limit) {
$data = $this->_add_continue($data);
}
$this->_data = $this->_data.$data;
$this->_datasize += strlen($data);
}
/**
* Writes Excel BOF record to indicate the beginning of a stream or
* sub-stream in the BIFF file.
*
* @param integer $type type of BIFF file to write: 0x0005 Workbook, 0x0010 Worksheet.
* @access private
*/
function _store_bof($type)
{
$record = 0x0809; // Record identifier
$length = 0x0008; // Number of bytes to follow
$version = $this->_BIFF_version;
// According to the SDK $build and $year should be set to zero.
// However, this throws a warning in Excel 5. So, use these
// magic numbers.
$build = 0x096C;
$year = 0x07C9;
$header = pack("vv", $record, $length);
$data = pack("vvvv", $version, $type, $build, $year);
$this->_prepend($header.$data);
}
/**
* Writes Excel EOF record to indicate the end of a BIFF stream.
*
* @access private
*/
function _store_eof()
{
$record = 0x000A; // Record identifier
$length = 0x0000; // Number of bytes to follow
$header = pack("vv", $record, $length);
$this->_append($header);
}
/**
* Excel limits the size of BIFF records. In Excel 5 the limit is 2084 bytes. In
* Excel 97 the limit is 8228 bytes. Records that are longer than these limits
* must be split up into CONTINUE blocks.
*
* This function takes a long BIFF record and inserts CONTINUE records as
* necessary.
*
* @param string $data The original binary data to be written
* @return string A very convenient string of continue blocks
* @access private
*/
function _add_continue($data)
{
$limit = $this->_limit;
$record = 0x003C; // Record identifier
// The first 2080/8224 bytes remain intact. However, we have to change
// the length field of the record.
$tmp = substr($data, 0, 2).pack("v", $limit-4).substr($data, 4, $limit - 4);
$header = pack("vv", $record, $limit); // Headers for continue records
// Retrieve chunks of 2080/8224 bytes +4 for the header.
for($i = $limit; $i < strlen($data) - $limit; $i += $limit)
{
$tmp .= $header;
$tmp .= substr($data, $i, $limit);
}
// Retrieve the last chunk of data
$header = pack("vv", $record, strlen($data) - $i);
$tmp .= $header;
$tmp .= substr($data,$i,strlen($data) - $i);
return($tmp);
}
}
?>
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