[cairo-bugs] [Bug 48260] New: PDF print output of Cairo has unneeded transparency with badly defined bounding boxes

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=48260

             Bug #: 48260
           Summary: PDF print output of Cairo has unneeded transparency
                    with badly defined bounding boxes
    Classification: Unclassified
           Product: cairo
           Version: 1.10.2
          Platform: All
        OS/Version: Linux (All)
            Status: NEW
          Severity: major
          Priority: medium
         Component: pdf backend
        AssignedTo: ajohnson at redneon.com
        ReportedBy: till.kamppeter at gmail.com
         QAContact: cairo-bugs at cairographics.org


For printing on Dabian and Ubuntu GTK/GNOME-based applications (like evince)
generate PDF with Cairo and send it to CUPS. CUPS calls Ghostscript to convert
this PDF into the printer's native data format.

Problem is that the PDF generated by Cairo renders very slowly with Ghostscript
in the printing-typical resolutions of 600dpi and more.

This is caused by pointless use of transparency also if only opaque objects are
drawn and in addition, the bounding boxes of the transparency groups are always
the entire page. Since Ghostscript has to allocate memory to hold the raster
data for each transparency the overall memory consumption can get multiples of
the memory needed for th final page's raster data, making the machine swapping
to the death.

Can this be improved? PDF-based printing got standard now.

Sample bug reports:

https://bugs.launchpad.net/ubuntu/+source/ghostscript/+bug/968785
https://bugs.launchpad.net/ubuntu/+source/ghostscript/+bug/668800 (comment #36)
http://bugs.ghostscript.com/show_bug.cgi?id=692959

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