Hi Hans, hi all,
I use overprinting only for the texts (not global). Most times the
texts are stored in a \[h|v]box first, before they are added to the rest
(offsets, background, whatever). So thinks look like this (very simplified):
\setbox\Textbox\hbox{\startoverprint Some text.\stopoverprint}
Overprinting should be activated only inside of this box. Sadly mkiv
adds this attribute to most of the graphics with text. The first
graphics is always OK, but the following graphics are overprinted as a
whole.
I have compared the pdf of pdftex and luatex and the main difference is,
that luatex 'optimizes' the overprinted texts by *grouping* them.
Instead of two or more independent areas (one /GSoverprint ...
/GSknockout for every text), like in mkii,
% pdftex
%----------------------------
/GSoverprint gs % text 1
BT
/Fm?? first overprinted text
...
/GSknockout gs
/GSoverprint gs % text 2
BT
/Fm?? second overprinted text
...
/GSknockout gs
%----------------------------
I get
% luatex
%----------------------------
/GSoverprint gs % text 1 and 2
BT
/Fm?? first overprinted text
...
/Fm?? second overprinted text
...
/GSknockout gs
%----------------------------
This is right from the point of overprinting, but the texts are still
part of different graphics (rendering is done at different times). I
guess this somehow corrupts the grouping. The first graphic in such a
group is always OK, all following graphics are overprinted as a whole. I
have tested this with more than two graphics (resulting in two multiple
groups) and I get the same effect.
No minimal yet. Any thoughts?
Best wishes, Peter
Hans Hagen schrieb:
Peter Rolf wrote:
Hans Hagen schrieb:
Peter Rolf wrote:
first tests show that there are still scope problems in mkiv (e.g.
a complete button is set to overprint instead of the text only).
no clue yet, but i'm working on it...
sure, as overprint is not aware of any content so you need to use
knockout then
mh, isn't \stopoverprint enabling knockout automatically?
or do i need a \ExtGState entry with knockout at the document level?
just started reading in the pdf reference manual...
it depends ... we have none: no entry at all, knockout: some nil
entry, overprint: special entry
the thing is that when we have globally overprint on, we need s local
knockout :
\startoverprint
... \bgroup ...
\startknockout
...
\stopknockout
... \egroup ...
\stopoverprint
is nicer than
\startoverprint
... \bgroup ...
\stopoverprint
...
\startoverprint
... \egroup ...
\stopoverprint
Hans
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Hans Hagen | PRAGMA ADE
Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
tel: 038 477 53 69 | fax: 038 477 53 74 | www.pragma-ade.com
| www.pragma-pod.nl
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