[webkit-qt] QtWebKit very slow compared to WebKitGtk (on top of directfb).

Benjamin Poulain benjamin.poulain at nokia.com
Mon Jul 18 02:59:40 PDT 2011


On 07/16/2011 01:24 PM, ext haithem rahmani wrote:
> When Running QtWebKit on top of directfb (qt-embedded 4.7.2) I noticed
> that the image decoding is very very slow
> compared to WebKitGtk.
> Some images are displayed in 3 secs compared to 0.3 secs.
> http://nontroppo.org/timer for example took 2200ms on webKitGtk
> however it needs more than 6000ms for the full load.
> (the scores are collected on a ST SoC.)
> I've found the following entry in the bugs.webkit.org
> <http://bugs.webkit.org> https://bugs.webkit.org/show_bug.cgi?id=27538
> <https://bugs.webkit.org/show_bug.cgi?id=27538>but the work done by
> Holger was not totally applied in QtWebKit
> especially the patch to use the webcore image decoders . is there any
> reason for that?
> the patches are a bit old compared to the current code. Does any body
> have an updated one applicable on the QtWebKit-2.2?

I doubt decoding is the issue. Except for the GIF format, the decoding 
of images is done by the usual libraries (libjpeg, libpng).

My guess is color conversion could be an issue depending on the target 
color format on your directfb. If the color format on 32 bits, the 
problem could also be on composition or the final color conversion to 
the target framebuffer.
(If the problem is on color conversion, scrolling is likely to be slower 
than usual as well).

I suggest you to profile your application (oprofile generally works 
great on Linux devices) and share the results here.


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