BarCode 128 generated via PHP and GD library

cjoki

Hello all, I am working on a php script to generate an image with the barcode 128 B (I will not be using the A or C). I have it displaying a barcode in firefox. When I print it it looks close to one generanted by a barcode application. The diference is that mine is slightly longer. Anyways given the same string the app generate code scans and mine does not. I believe everything is in order...but I must be missing something simple here...suggestions? This is the hash_code_128.php script referenced in the main script. The source for the codes came from wikipedia http://en.wikipedia.org/wiki/Code_128[^]

<?php
$b_chr = array(); // character lookup
$b_enc = array(); // encoding lookup
$stop = "11000111010";
$term_bar = "11";
$b_chr['00'] = " ";
$b_chr['01'] = "!";
$b_chr['02'] = '"';
$b_chr['03'] = "#";
$b_chr['04'] = "$";
$b_chr['05'] = "%";
$b_chr['06'] = "&";
$b_chr['07'] = "'";
$b_chr['08'] = "(";
$b_chr['09'] = ")";
$b_chr['10'] = "*";
$b_chr['11'] = "+";
$b_chr['12'] = ",";
$b_chr['13'] = "-";
$b_chr['14'] = ".";
$b_chr['15'] = "/";
$b_chr['16'] = "0";
$b_chr['17'] = "1";
$b_chr['18'] = "2";
$b_chr['19'] = "3";
$b_chr['20'] = "4";
$b_chr['21'] = "5";
$b_chr['22'] = "6";
$b_chr['23'] = "7";
$b_chr['24'] = "8";
$b_chr['25'] = "9";
$b_chr['26'] = ":";
$b_chr['27'] = ";";
$b_chr['28'] = "<";
$b_chr['29'] = "=";
$b_chr['30'] = ">";
$b_chr['31'] = "?";
$b_chr['32'] = "@";
$b_chr['33'] = "A";
$b_chr['34'] = "B";
$b_chr['35'] = "C";
$b_chr['36'] = "D";
$b_chr['37'] = "E";
$b_chr['38'] = "F";
$b_chr['39'] = "G";
$b_chr['40'] = "H";
$b_chr['41'] = "I";
$b_chr['42'] = "J";
$b_chr['43'] = "K";
$b_chr['44'] = "L";
$b_chr['45'] = "M";
$b_chr['46'] = "N";
$b_chr['47'] = "O";
$b_chr['48'] = "P";
$b_chr['49'] = "Q";
$b_chr['50'] = "R";
$b_chr['51'] = "S";
$b_chr['52'] = "T";
$b_chr['53'] = "U";
$b_chr['54'] = "V";
$b_chr['55'] = "W";
$b_chr['56'] = "X";
$b_chr['57'] = "Y";
$b_chr['58'] = "Z";
$b_chr['59'] = "[";
$b_chr['60'] = "\\";
$b_chr['61'] = "]";
$b_chr['62'] = "^";
$b_chr['63'] = "_";
$b_chr['64'] = "`";
$b_chr['65'] = "a";
$b_chr['66'] = "b";
$b_chr['67'] = "c";
$b_chr['68'] = "d";
$b_chr['69'] = "e";
$b_chr['70'] = "f";
$b_chr['71'] = "g";
$b_chr['72'] = "h";
$b_chr['73'] = "i";
$b_chr['74'] = "j";

Marc Firth

I came across this a while ago - dunno if it'll help:

<?php

UPCAbarcode('12345678901');

?>

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cjoki

I got it working. I had a few issues that needed to be adressed. 1) My checksum made a mistake of just using the modulus value as a lookup, when I really needed to add 32 to the value and find the ascii character it represents. Then I can find the hash code based on that and add it to the bar code string.

$checksum = $checksum + 32;
$checksum2 = chr($checksum);
$key = array_search($checksum2,$b_chr,true);
$bcstring.=$b_enc[$key].$stop.$term_bar;

I did not draw the final termination barcode in my for loop due to a simple logic error. I corrected it with and a "or" to check for the end of the barcode string so I write the last part.

if($bcstring[$i]==0 && $bcstring[$i]!=$last_char || $i == $bc_cnt-1)
{
// stopping new bar
// bool imagefilledrectangle ( resource $image , int $x1 , int $y1 , int $x2 , int $y2 , int $color )
imagefilledrectangle($im, $start_x, $pad_top, $start_x+($stop_x*$size)-1, $height, $black);
$stop_x = 1;
}

it is all working. If anyone wants to use this code, enjoy! Of course a mention is always nice ;)

Spadino70

Hello cjoki, I try to explain, but not very practical with English (I'm Italian) and I just started with php ... I am trying your code but you probably have not entered correctly the last few lines of code that you posted, because the barcode is almost always correct but sometimes lack a little bit. Here how I use it, if you can help me. Thanks

<?php
/*
This is a program to generate a code 128B barcode and returns an image.

	Chris J, 2009-11-04
\*/


$string=urldecode($\_GET\['string'\]);
$size=urldecode($\_GET\['size'\]);
$height=urldecode($\_GET\['height'\]);

// $string is string to convert to bar code
	
// $size is the pixel width of the bar code and is used as a base unit for each barcode/space
// based on the # of 0's or 1's in a row.
// for example the stop bar code hash is 11000111010. This is drawn as a bar 2 units wide, a space 3 units wide, a bar 
// 3 units wide, a space 1 unit wide, a bar 1 unit wide followed by a space 1 unit wide. If the size is equal to 3 (for 3 pixels)
//	this will mean the barcode for the stop is bar 6 pixels, space 9 pixels, bar 9 pixels, space 3 pixels, bar 3 pixels and space
// 3 pixels. The entire code will messure 33 pixels in width. of course that is just for the stop (the end of the code 128 barcode).

// $height is the height of the barcode in pixels. There must be room for for some padding on the top and bottom and room for
// the text of $string to be printed just under the barcode.

// at the front and back of a code 128 barcode is a blank space called the quiet zone. It should be 10 times the unit ($size in my function)
include('hash\_code\_128.php');
$bcstring = '';
$cnt = strlen($string) ;

$quiet\_zone 	= 10\*$size-1;
$pad\_top 			= 5;
$pad\_text 		= 3;
$font\_size 		= 5;
$pad\_bottom 	= 5;
$font\_left 		= $quiet\_zone;
$font\_top 		= $pad\_text + $height; 
$ttl\_width		= ($quiet\_zone\*2)+($size\*($cnt+3)\*11)+2; // include string length + start + stop + checksum + front and back quiet zones
$ttl\_height		= $pad\_top + $pad\_text + $font\_size + $pad\_bottom + $height; 




$running\_checksum = 104; // START B hardcoded...
$bcstring.=$b\_enc\['104'\];
// build the barcode
for($i=0;$i<$cnt;$i++)
{
	$position = $i+1;
	$key = array\_search($string\[$i\],$b\_chr,true);
	$bcstring.=$b\_enc\[$key\];
	$running\_checksum+=($position\*$key);
}
$checksum = $running\_checksum%103;
//~ $bcstring.=$b\_enc\[$checksum\].$stop.$term\_bar;

$checksum = $checksum + 32;
$checksum2 = chr($check

cjoki

here is the full code that is in production still. maybe this will help. cjoki

<?php
/*
This is a program to generate a code 128B barcode and returns an image.

	Chris J, 2009-11-04
\*/
function gen\_code128($string, $fid, $size = 1, $height = 50, $show\_text = true)
{

	// $string is string to convert to bar code
	
	// $fid is the filename, it will default to the $string if no is provided
	
	// $size is the pixel width of the bar code and is used as a base unit for each barcode/space
	// based on the # of 0's or 1's in a row.
	// for example the stop bar code hash is 11000111010. This is drawn as a bar 2 units wide, a space 3 units wide, a bar 
	// 3 units wide, a space 1 unit wide, a bar 1 unit wide followed by a space 1 unit wide. If the size is equal to 3 (for 3 pixels)
	//	this will mean the barcode for the stop is bar 6 pixels, space 9 pixels, bar 9 pixels, space 3 pixels, bar 3 pixels and space
	// 3 pixels. The entire code will messure 33 pixels in width. of course that is just for the stop (the end of the code 128 barcode).
	
	// $height is the height of the barcode in pixels. There must be room for for some padding on the top and bottom and room for
	// the text of $string to be printed just under the barcode.
	
	// at the front and back of a code 128 barcode is a blank space called the quiet zone. It should be 10 times the unit ($size in my function)
	
	// the $show\_text parameter determines if a string will display under the barcode, this string will be the text version of the barcode.
	
	include('hash\_code\_128.php');
	$bcstring = '';
	$cnt = strlen($string) ;
	
	$quiet\_zone 	= 10\*$size-1;
	$pad\_top 			= 5;
	$pad\_bottom 	= 5;
	$ttl\_width		= ($quiet\_zone\*2)+($size\*($cnt+3)\*11)+2; // include string length + start + stop + checksum + front and back quiet zones
	
	if($show\_text)
	{
		$pad\_text 		= 3;
		$font\_size 		= 5;
		$font\_left 		= $quiet\_zone;
		$font\_top 		= $pad\_text + $height; 
		$ttl\_height		= $pad\_top + $pad\_text + $font\_size + $pad\_bottom + $height;
	}
	else
	{
		$ttl\_height		= $pad\_top + $pad\_bottom + $height; 
	}
	$running\_checksum = 104; // START B hardcoded...
	$bcstring.=$b\_enc\['104'\];
	// build the barcode
	for($i=0;$i<$cnt;$i++)
	{
		$position = $i+1;
		$key = array\_search($string\[$i\],$b\_chr,true);
		$bcstring.=$b\_enc\[$key\];
		$running\_checksum+=($position\*$key);
		//	echo "<p>pos: ".$position."<br>char: ".$string\[$i\]."<br>key: ".$key."<br&g