[cairo] PDF backend generates images that gs can't display etc

Carl Worth cworth at cworth.org
Thu Feb 25 10:22:17 PST 2010


On Sat, 20 Feb 2010 01:07:50 +0100, Arjen Nienhuis <a.g.nienhuis at gmail.com> wrote:
> Solution 1: An api to create v1.2 PDFs
> - Cairo would be compatible with 99% of all pdf viewers and almost
> compatible with PDF/A
> - A lot of RIPs and PDF tools used in the printing industry don't
> really support PDF 1.4. This is very specialized software (and
> expensive) and cannot be upgraded.

Yes. Targeting a particular PDF version makes a lot of sense if there
are users that really need this. See cairo_ps_surface_restrict_to_level
for some very similar API in cairo's PostScript backend.

Anyone motivated to tackle that? (It's really just a matter of inserting
a bunch of CAIRO_STATUS_UNSUPPORTED returns at the right places to
trigger fallbacks for things not supported in PDF 1.2).

> Solution 2: An api to disable masks and use fallbacks.
> - Solves all problems for many viewers including acrobat 6, 7, 8 and
> ghostscript.

Right. This is what I imagined when I said "we don't currently have API
to workaround viewer bugs". This would only be needed if users didn't
find solution 1 adequate for some reason.

> Solution 3: Output all masks as white masks.
> - Acrobat v7 works if the masks are white. I don't know why.

This one doesn't make sense to me at all. How can it be interesting to
generate a mask other than what was actually requested? (Or maybe I
misunderstood the idea here.)

-Carl
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