[Okular-devel] PDF thumbnail plugin

[Peter Penz]

Hi Pino,

On Wednesday, 10. June 2009 16:31:26 Pino Toscano wrote:
> Hi Peter,
>
> > I had a short look on the bug https://bugs.kde.org/show_bug.cgi?id=190600
> > (= "Hovering large PDFs slows down KDE"). When hovering a PDF in e. g.
> > Dolphin, a preview of the PDF will be generated by using KDE's thumbnail
> > mechanism.
> >
> > The corresponding thumbnail plugin that seems to have problems with huge
> > PDFs is located at kdegraphics/thumbnailers/gscreator.cpp
>
> That thumbnailer invokes `gs` (ghostscript) to get the image of the first
> page of the PS/PDF document (and coverting DVI files to PS, first). Do you
> get similar blocks/slowdowns if running `gs somebig.pdf` on command line?

No, when using the commandline everythings seems to be fine...

>
> > I did not have a
> > look how Okular generates the thumbnails for PDF pages, but I was
> > wondering whether this code could also be moved to the PDF thumbnailer to
> > solve the issue mentioned above...
>
> Okular uses the Poppler library for PDF documents. Most probably it could
> be done an own PDF thumbnailer which just uses Poppler for thumbnails
> (should be like 10 lines or so), but would be interesting to know whether
> the problem is actually just ghostscript crawling with very big documents,
> or the documents themselves are "heavy".
> What is missing is also the indication of the actual "slowness", ie if KDE
> 4 becomes slow because the CPU is very busy in rendering complex documents
> (in which case, even Poppler could give the same problems), or there's too
> much I/O job, or RAM usage, etc.

I did some further tests in the meantime with several reboots and checked the 
CPU load. It seems to be related with Nepomuk, which consumes 100 % CPU load 
for a few seconds on my system. When turning off Nepomuk and Strigi I've no 
freezes anymore when hovering problematic PDFs...

I'll be at the Nepomuk coding sprint next week and hopefully I can discuss 
this kind of issues there with Sebastian Trüg - sorry for the noise, the issue 
seems to unrelated to the PDF thumbnailer...

Thanks for your fast reply!
Peter