Qt4 and QTreeView performance

When I started working on complete overhaul of KleanSweep GUI (moving from KDE 3 to Qt4) I soon faced problem with slow QTreeView performance when using my own item model. To make the long story short, with around 1.6 mln records the QTreeView was completly unusable taking tens of seconds to redraw when scrolling its contents. I googled a lot only to discover other people had similar performance problems with Qt Model/View architecture.
I almost gave up, until my recent discovery: the uniformRowHeights property of QTreeView. It indicates (if true) that all items in the view have the same height - and allows the view to perform some optimizations. This solved the performance problem I was facing! So now my SQLite-based model works fine and the new KleanSweep (still W.I.P) will be capable of displaying millions of files with little memory footprint!

Fell in love with Debian Lenny

Debian 5.0 (Lenny) has been released. I've been running it for about one month (installed from a release candidate iso) and I must admit I'm absolutely delighted by it. Being an Ubuntu user before I already got used to apt-get, synaptic and other goodies. Where Lenny really shines (compared to Ubuntu) is:

• it's rock stable; I haven't had a single stability issue so far
• it's well tested and you can really feel it. I haven't experienced any stupid / trivial / obvious bugs that  should have been detected and fixed (as it was often a case for Ubuntu or openSuse). It just feels the release was not rushed as it often happens to commercial distros.
• it's not bloated (number of services is reduced to the minimum, no desktop indexing like Beagle or Tracker is installed by default etc.)
  
• no experimental or unfinished features (e.g. no PulseAudio...)

All in all, Lenny seems to be a really good and solid release. Long live, Debian project!

A bit of self-promotion & job status update

I've just received a nice declaration from my university. It states that I've graduated Computer Science within 5% of best students (in 2008) :). This is very refreshing given my recent job changes (to remind you: Astaro closed its R&D office in Poland) and it was also a nice and unexpected surprise!

When it comes to job changes, starting from March 2nd I'll be working for my former company (Alcatel-Lucent) again.

Telescope case

I've finally made myself a case to carry my MAK127 telescope and another one to carry accessories (eyepieces, finder etc.). It took me around three hours to accommodate each case for its duty - main job was to cut sponge so that telescope and accessories all fit and are protected against shock (BTW, as you can see on the photos, the telescope case is made of a casual toolbox). My next target is a case / bag for EQ3-2 mount, but this seems to be more problematic... Any ideas?

Poszukuję pracy...

Początek roku okazał się dla mnie mało szczęśliwy... Okazało się , że Astaro - firma, w której pracowałem przez ostatni rok - zmuszona została do zamknięcia oddziału R&D w Bydgoszczy. Powód: kryzys, szczególnie dotkliwy w Niemczech, gdzie znajduje się główna siedziba Astaro.

Tak więc, jeśli Twoja firma poszukuje doświadczonego programisty (C++, Java, Python, Perl, Linux) do pracy na terenie Bydgoszczy lub okolic, to proszę o kontakt.

Więcej informacji o moich kwalifikacjach tutaj:

• profil goldenline.pl
  
• profil linkedin.com

Vice 2.1

A new version of Vice - popular C64 emulator - has been released on Dec 19th 2008. This version brings some small improvements - most notably fullscreen mode finally works and uses xrandr! This means much more fun & immersion when watching old C64 demos :).

This brings me to a bunch of new demos released in 2008. It turns out there are still guys out there who can amaze the world by squeezing last bits out of C64... If you had C64 and you've ever felt a bit nostalgic about it, I suggest you install vice and watch these demos:

• "Edge of Disgrace" by Booze Design, 1st place at C64 Demo Competition at X'2008.
• "Natural Wonders 2" by Oxyron, 2nd place at X'2008.
• "Pearls for Pigs" by Xenon, 3rd place at X'2008.

Going back to 2007... Check out "Desert Dream" demo by Chorus & Resource - these guys made an excellent remake of the popular Kefrens' demo from Amiga. Simply amazing.

BTW... A nice video about C64 internals and capabilities has been recently made available - see here.

CD/DVD burning broken in openSuse 11.1

CD/DVD burning seems to be broken/not working by default in openSuse 11.1 - at least on my PC with a pretty standard 5-years old DVDRW drive from LG. There seems to be a problem with device permissions: the /dev/sr0 device (my DVDRW drive) is owned by root:disk and therefore not accessible for CD burning software (/usr/bin/wodim to be exact) when executed by regular users. Here is a workaround for this problem:

• make your user a member of "cdrom" group
• create /etc/udev/rules.d/99-my.rules file with the following entry:
  KERNEL=="sr*[0-9]", GROUP="cdrom", MODE="0660"
• set setuid bit for /usr/bin/wodim (note: this has some security implications; make sure you understand what it is all about):
  chmod u+s /usr/bin/wodim
• reboot

Remarks:

• this assumes your CD/DVD writer is mapped to a /dev/sr* device (should be the case for all drives, but I couldn't verify that).
• if this rule causes any side-effects to other /dev/sr* devices you may have installed, restrict the rule for specific device instead of using regular expression.
  

It would be of course possible to make your user a member of "disk" group, but it would be a real security problem, as this would also allow for low level access to hard disks.

Updates:

• the bug has already been reported on Novell's bugzilla
  
• making wodim setuid seems to be not needed after all (udev rule is enough).