[Haskell-cafe] Re: bug in HPDF?

[alpheccar]

Roman,

The text monad is very low level and its functions are mapping  
directly to the PDF text environment commands.

"text" function is generating two PDF commands : Td and Tj. In Adobe  
PDF spec :

Td : Move to the start of the next line, offset from the start of the  
current line by (tx , ty ). tx and ty are numbers expressed in  
unscaled text space units.

Tj : Show a text string.

So, the behavior is correct and HPDF really needs a documentation :-)  
and some cleaning of the API.

Thanks,
Christophe.

> Here is a program which illustrates an unexpected behaviour:
>
>  import Graphics.PDF
>
>  main = runPdf "bug.pdf" standardDocInfo (PDFRect 0 0 100 100) pdf
>      where
>      pdf = do
>          p <- addPage Nothing
>          drawWithPage p $ drawText $
>              sequence $ replicate 10 $
>                text (PDFFont Helvetica 10) 10 10 (toPDFString "ABC")
>
> What I expect here is "ABC" printed 10 times on the same place  
> (starting
> at (10,10)). What I see (in Okular) is ABC printed each time in the  
> new
> place like this:
>
>   ABC
>  ABC
> ABC
> ABC
>
> What's happening here? I'm using HPDF-1.4.1 from Hackage.
>
> -- 
> Roman I. Cheplyaka :: http://ro-che.info/
> "Don't let school get in the way of your education." - Mark Twain

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