[reportlab-users] Code 11 barcode bug

[Robin Becker]

On 28/02/2010 22:18, Sergiu Iordache wrote:

> Hello,

>

> After trying to use the Code 11 barcode drawing function I am pretty

> sure that it is bugged. It doesn't seem to generate the correct

> barcode, but I haven't found the bug origin or solution yet. If I do,

> I'll post the solution here.

>

> Here[1] is the example code to generate a Code 11 barcode for the

> number 1 . It generates this barcode[2].

> The result is not correct, as the last character does not correspond

> to the first one and does not have enough characters. Here is the same

> number generated using an online generator [3]

>

> If anyone figures out the solution please post it here. The bug is

> most probably located here[4].

>

> Thanks a lot,

> Sergiu

........

OK I think I found two problems here.

First off my googling reveals this

http://www.mecsw.com/specs/code_11.html

that seems to indicate that both checksums should be mod 11 and not as in the 
current code mod 11 & mod 10. Secondly I checked and the decompose step was 
wrongly calculating the intermediate characters.


I think the attached is an improvement. Can you test it and report if it's 
better for you? I don't have a reader which works with code11 so it would be 
valuable if you can check if the second check digit is being correctly computed.

-- 
Robin Becker
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