Andreas
Qt
KDE
Posted by Andreas
 in Qt, KDE
 on Monday, April 14, 2008 @ 14:35

Greetings from Helsinki airport. I came back from my visit to Milan (thanks Riccardo for arranging the sprint, it was great to be there!) at around 02:30am this morning. Now I’m waiting for my connection through Frankfurt to go to Brazil.

I chatted with Thiago, who’s there already, and he said it’s a good 28C degrees in Sao Paolo right now. Here I am with my suede leather jacket, long jeans and a sweater, my suitcase has only black t-shirts in it, no sun glasses and no sunscreen, feeling pretty silly. He-he! ;-)

Milano was fun, I think I’ll want to sign up for more of those events in the future. My idle task was optimizations in QGraphicsScene’s sorting and transform code (I’ve managed a 15-30x speed-up so far, will submit changes to main/4.5 some time when I come back, see patch below). There’s still more optimizations to come, I think I’m just in the flow with this stuff now. Fun to help out with the port to using QGraphicsWidget, and also with some work we did to speed up the SVG cache. Sorry that I couldn’t stay for the API review. :-/

I’m bringing some feedback home to our team in Oslo:

* QtSvg could use some optimization work
* It would be very nice if QtSvg covered the entire SVG 1.1 Tiny standard
* I should write a blog or a Qt Quarterly article (or both) about tricks to make graphics fast / like device space pixmap caching for static content.

Now I’ve been in Helsinki, holding a presentation about our ideas for improving widgets, theming, animations and the like. Fun and interesting! And now I’m headed to Brazil to do the same. Wee!

PS: Apply to Qt it you have problems with performance with deeply nested structures in Graphics View: http://www.andreas.hanssen.name/scene-speed.txt (no warranty!)

4 Responses to “Four down, ~six to go”

» Posted by stelt
 on Monday, April 14, 2008 @ 15:51

You/Qt also presenting at the SVG world conference, this year in the South of Germany?
See http://svgopen.org for the opportunity

» Posted by Rob
 on Wednesday, April 16, 2008 @ 20:01

Andreas - Glad to hear of the huge speedups to QGS. I’ve got scenes with between 300 and 600 thousand items in them, and things bog down pretty badly when selecting and dragging. Profiling the code puts much of the blame on qt_closestItemFirst(), so I’m happy to hear that’s faster. Any idea when it’ll hit the builds? Thanks, Rob

» Posted by hhartz
 on Thursday, April 17, 2008 @ 11:46

When you’re back in Norway I will show you how sunburnt you can get from spending 4 hours in a boat on Lake Travis in Texas. Get some sunscreen! ;-)

» Posted by Thomas Gern
 on Thursday, April 17, 2008 @ 19:21

Hi Andreas,

I could not get the information to which version of QT this patch could be applied?

Best regards,

Thomas



© 2008 Nokia Corporation and/or its subsidiaries. Nokia, Qt and their respective logos are trademarks of Nokia Corporation in Finland and/or other countries worldwide.
All other trademarks are property of their respective owners.