[cairo] Blurred output when printing certain pdfs with evince

[Adrian Johnson]

M_May at web.de wrote:
> Hi!
> 
> I have a problem printing some pdf documents with evince, using cairo up to 1.4.12:
> The output of some fonts is very blurred, while in the same documents
some mathematical
> expressions result in good quality. If i print two pages (instead of
one) on one page of paper,
> the output is good again. See launchpad bug
https://bugs.launchpad.net/bugs/150187 for
> some attachments. I am not 100 % sure, if it is a problem of cairo,
but since the newer
> versions of evince use it for printing...?
> 

I could not reproduce this with any of the PDFs attached to the
launchpad bug. It would be helpful to see the PDF that was used to print
the one_page.ps attachment.

The most likely explanation is in comment 2 of the poppler bug report
[1]. If the PDFs are using Type 3 fonts, poppler prints them using image
masks. The comment indicates there is an image scaling problem in poppler.

In cairo 1.4.x the PostScript backend has the limitation that any page
containing some transparency results in the entire page drawn as
fallback image. Type 3 fonts drawn as image masks will cause these
fallbacks. This has been fixed in cairo 1.5.x. However using 300dpi
fallback images should not cause blurry fonts. So the problem is most
likely with the way poppler or cairo scales the image masks.

[1] http://bugs.freedesktop.org/show_bug.cgi?id=12769#c2