[barcode] streaming mode for pcl output

[Wolfgang Rohdewald]

Hi,

I needed to add barcode output to a legacy application that generates 
PCL5. So I tried barcode but since it always does absolute cursor 
addressing and outputs a form feed I could not have used it like that.

I was originally planning to deliver several patches but I worked 
against the released 0.98 and only when I was done found the cvs
online repository. So now it is just one patch but still manageable
I think.

It does:

1. remove unused variable k from pcl.c

2. use relative cursor positioning in pcl.c. Only the first      
   positioning is absolute. This introduces the usage of
   3 more PCL commands: ESC *v#O, ESC *v#T, ESC &a#P. As
   far as I know they were always part of PCL5 and all PCL5 printers
   I know support it. Using them is the only way I know to 
   print columns right aligned with PCL (unless you use monospace 
   fonts of course). The produced PCL output is shorter (could
   be shortened even more but unimportant) and does not contain
   line feeds anymore.

3. introduce a new streaming mode "-s". Only for pcl output and not 
   in table mode (this is checked for). In this mode, everything is
   done in relative address mode. Default is to position the bar-
   code such that its text is aligned with previously printed text.
   After printing the barcode, cursor is at same Y but X is after the
   barcode, using bc->margin for distancing. In streaming
   mode, the charset encoding and the font are never changed, it is
   expected to be done by the surrounding PCL code generated by the
   printing application.

4. allow negative values for -g xoffset and yoffset
   like -g 30x20+5-1.5 for fine tuning the position.
   

Use case: The application might generate a line like

Reinigungsmittel: EAN13START -b761005201696 -g30x10 EAN13END  

Then a filter will replace that by the output of barcode. Options
-s and -P are default.

I also have a python program that scans PCL5 and makes PDF out of
it, using the PyQt4 libraries. That will become open source too
some time this year. Of course it only does just what I need.
It supports defining background images like company logos, and
since today it also handles barcode output.


-- 
Wolfgang
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