[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 08:00:49 PDT 2009


--- Comment #25 from Chang Shu <Chang.Shu at nokia.com>  2009-10-14 08:00:48 PDT ---
(In reply to comment #24)
> Created an attachment (id=41099)
 --> (https://bugs.webkit.org/attachment.cgi?id=41099) [details]
> API for QImageReader...
> My metric skills are not so good but this looks like a 1.6MB memory saving on
> images from my benchmark. Can you confirm that you see similiar numbers?

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.

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. Besides, even put the
logic in Qt, we still have the headache of how to trigger this: whether through
qwebsettings api, or by ifdef(SYMBIAN) or for all Qt platform.

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