Playing with Qt Jambi

Over the last couple of days I've been playing around with Qt Jambi, the Qt bindings for Java, which are pretty cool. I haven't used them that much so far, but they seem really nice. I'd been starting to write this little car game thing, which is more a proof of concept at the moment, which I've now ported to be able to use Qt.

Try it as an applet here (note this is using ordinary Java swing, not Qt as I'm not sure if you can embed a Qt widget in an Applet (or in any AWT or swing element). Then there'd be the trouble of having to download Jambi which is fairly big.

Use your arrow keys to drive around, Ctrl+R resets (in hindsight, not a good choice as it coincides with firefox's and epiphany's reload page shortcut (possibly other browsers too)). The physics is terrible, but I find it fun just driving around, making pretty patterns. You might need to click the applet to give it focus.

Or you can download it here. That includes the source. To run it using qt, it will need to find the Jambi jar file, and it looks in the current directory and "/usr/share/java/qtjambi.jar" (the latter is the default location in Ubuntu (and possibly other distros), so you just need to install the jambi package). You can download Qt Jambi here. Then you need to pass the command line option '--qt'. By default I try and use opengl (which is faster), if it doesn't seem to work, try '--qt --no-gl' to use the regular qt rendering engine.

The number in the top right corner is how many milliseconds it's taking to draw each frame (averaged over the last 100 frames I think). I found Qt with no opengl to be about the same speed as Java swing at 640x480, which I found surprising, I thought Qt would be significantly faster, though at full screen swing slows right down, while Qt only takes a little bit longer, and with opengl it's about 25% faster. YMMV.

I had to be a bit sneaky when writing this so that the swing version would run fine even without the Qt libraries. My first (which I thought was nicer) implementation didn't work, as there were references to the Qt classes in the classes that were being run, even though they weren't used. So when I redid it I had to split everything up, a swing version and a Qt version, so that when swing was being used there would be no references to the Qt classes. I wasn't sure that that would work, but it did, which is pretty cool. Enjoy.

Edit: It appears it's pretty hard for this thing to regain focus, I should probably look into that, enjoy it if you can get it to work, otherwise download the jar, that's more likely to work correctly.