[Webkit-unassigned] [Bug 29279] [Qt] Use RGB16 format for images on Symbian platform

bugzilla-daemon at webkit.org bugzilla-daemon at webkit.org
Wed Oct 14 18:23:45 PDT 2009


--- Comment #26 from Holger Freyther <zecke at selfish.org>  2009-10-14 18:23:44 PDT ---
(In reply to comment #25)

> I tried Holger's code locally. First, I tried it on Symbian OS with local
> webkit database. However, since our local webkit does not have the latest image
> re-work, the code didn't work after I simply call setPreferredFormat in
> setData. I need more time to do the debugging. I also tried it on Qt Linux. I
> applied the patch on Qt4.5. I see the patch is executed successfully. However,
> there is a call to buffer->asNewNativeImage() inside function
> ImageSource::createFrameAtIndex(). This converts 16bit image back to 32bit
> image as the latter is the native format. And this explains why I didn't see
> any improvement through memory monitor tool.
> Good that in Qt NSP version, the conversion to native format won't happen
> automatically(in QPixmap::fromImage()). Since NSP does not work on Linux, I
> have to setup a new work environment to test this.

Note, my 1.7memory saving is not taking the QImage->QPixmap into account. In my
benchmark asNewNativeImage is not called at all. I have created bug #30211 to
make use of QImage instead of QPixmap for painting but I have not yet
benchmarked it.

> Saying all the above, I am concerned about the availability of Holger's code.
> It seems too late to wait for 4.7. I am wondering if we can do this
> convert-to-preferred-format logic in
> ImageDecoderQt::internalHandleCurrentImage() for now.

No. We are fixing things where they need to be fixed. I have no idea about
constraints but you will probably have more than one patch to Qt when doing a
release/deployment. Just add the API after Qt has agreed that it will be

Currently I'm not really convinced that the 1.7MB is a big difference, do you
have other data showing a bigger saving?

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