[Dev-luatex] problems with the mediabox
indiego at gmx.net
Fri Sep 18 15:18:33 CEST 2009
Peter Rolf schrieb:
> I still have preflighting problems with the mediabox of luatex. It's
> accuracy is sufficient for printing, but using the values for a
> preflight is troublesome.
> An example: if I define a A4+ paper (303mm x 216mm) I get a mediabox
> of 303.0mm x 215.999mm. Hans has already restricted the trailing
> numbers of the trimbox/cropbox values in ConTeXt to adapt the accuracy
> (else rounding of the mediabox can lead to a bigger trim|cropbox,
> which is against definition). Anyhow, this is not enough for this
> MediaBox (mm): 303.0x215.999 (0.0/0.0/303.0/215.999)
> CropBox (mm): 303.0x216.0 (0.0/0.0/303.0/216.0 )
> TrimBox (mm): 303.0x216.0 (0.0/0.0/303.0/216.0 )
> MediaBox < CropBox|TrimBox
> So using the same number of digits after the point (%.3f) does not
> solve the problem.
oops, actually it's %.4f
> Setting the width to 216.001mm in this example helps, but this is
> MediaBox (mm): 303.0x216.0023 (0.0/0.0/303.0/216.0023 )
> CropBox (mm): 303.0x216.00101 (0.0/0.0/303.0/216.00101)
> TrimBox (mm): 303.0x216.00101 (0.0/0.0/303.0/216.00101)
> If you use some bleeding offset (in the A4+ example normally 3mm on
> each side) the problem vanishes. But for PDF/X you have to set the
> crop-|trimbox anyway, regardless if you use a bleeding offset or not.
> Possible solutions:
> - read access to the mediabox values, so that rounding errors can be
> - use the same calculation routine for all pdf boxes (e.g. a luatex
> library function)
> - ??
> Any comments are welcome.
> Best wishes, Peter
> dev-luatex mailing list
> dev-luatex at ntg.nl
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