Tag Archives: linux

A workaround for misbehaving X citizens

Some programs (most notably amongst those I use firefox and pidgin) don’t work properly with shift-insert for pasting from the primary X Selection. If you’re like me and virtually live in the command line, this is a real pain in the ass. It became more of a pain in the ass recently because I’ve started using a graphics tablet instead of a mouse, so no longer have a middle click. I could no longer paste from IRC into firefox.

After some hacking around, I settled on the following solution. “xsel -o -p | xsel -i -b” dumps the primary X selection into the clipboard (xsel is a nice little application. You should probably have it installed). So I’ve bound this to a shortcut in xmonad and now can at the press of a magic key combination take the current selection and make it pasteable. Hurray.

Not really LÖVING it

So I spent yesterday playing around with LÖVE, a really cute little platform for writing 2D games. It got linked on reddit on friday, and it looked neat so I thought I’d give it a try.

As you can tell from the title, this is not going to be a very positive post. So in order to brighten the mood I’m going to start by saying positive things about it:

I’ve been saying for ages that I wanted to play around with creating little games. I’ve never gotten around to doing so. LÖVE made it sufficiently easy for me to get started that I no longer had an excuse for not doing so.
It’s really very good at getting all the annoying cruft of creating a basic game out of the way.
I had a lot of fun playing with it.
I’m really glad I gave it a try, and if you’ve never written a game before and want to, you probably should too.

Also, the website is adorable.

Unfortunately, that’s about where the positive side of things stops.

First off, the biggest problem with it is that it’s really unreliable. It will sit on a CPU and eat 100% of it, for even the smallest of games. It seemed very crashy – on my work PC it tended to randomly crash other applications. People who tried to play my games said that it seems to crash itself and other things when you try to close it (this was under both macs and windows. I never had this problem under linux). Between these two factors I’d basically never consider it for a real game. Hopefully both will be fixed at some point. (Yes, yes, I know, open source, I should look into it. Unfortunately it seems to be written in C++, which I have approximately zero interest in writing).

The other major problem with it is that it’s actually not very powerful. What it basically comes down to is an infrastructure for loading files, an ok graphics API and fairly basic physics and sound APIs (there’s also an animation API which I didn’t bother to look at. It may be better than the others, I don’t know). So although it helps you get started it doesn’t really do much for you once you have.

As an example to illustrate the above: I had a bit of a play with the physics engine. Basically I created a green square that could jump about (he’s a very abstract representation of Victoria’s very abstract representation of a frog). That worked quite nicely – he could jump, he could move from side to side, he could land on stuff.

The point at which it stopped working nicely was when I wanted him to not be able to jump while already in mid air. See, it turns out that the physics engine has no way (or rather no way exposed in the API) of detecting if two bodies were in contact, so I couldn’t easily detect if he was on the ground or not. I asked in #loveclub on freenode (a much less dubious channel than the name might suggest), and various things were suggested. The best idea I encountered was checking vertical distance from the point of contact. This unfortunately proves to have a bunch of problems as well. The method I eventually settled on was that he could only jump if his vertical speed was already zero (actually, < 0.001) and hope that the player’s reactions weren’t good enough to jump during hang time.

At this point I more or less decided I’d had enough of the physics engine. I went back to the first game I’d made, turned it into something that was actually a proper game (it hadn’t previously been possible to lose. Now it’s only really hard to lose) and declared myself all out of LÖVE. It was a fun little encounter, and I do hope they do well, but unfortunately I’m not really left with any desire to use it.

If you want to check out the code I wrote for this, it’s available from the github repo. Be warned though: It’s really bad. It started out slightly crummy because I was just exploring the API, and then in that last “right, let’s get something actually playable” push I started factoring things out nicely before I realised that I was never going to touch the code again and just brutally copied and pasted and hacked until it worked. I should also warn you that the games themselves are correspondingly lame. :-)

(As an aside, also in that repo are today’s experiments at recreating something like the Love API but more reliable and/or powerful in Scala. But more on those later)

Not really an announcement: GUI frontend to Scala Interpreter

So, I’ve finally got sick of the unusable command line interface to the Scala interpreter.

Don’t get me wrong, I like command line interfaces. But I’ve always found command line interfaces written in Java to be pretty horribly unusable, and the variety of different quirks shown by the scala one between windows and linux is pretty gruesome.

Anyway, the upshot is that I’m building a simple GUI frontend to it. It turns out that the interpreter API is actually really easy to work with – it only took me about half an hour to hack together a basic working frontend (after some… minor issues with Java’s IO API)

So far this isn’t really in a state that other people can use it – no proper buildscript, the GUI frontend is hacked together in the interface designer and doesn’t handle resizing properly at all (so is probably broken on any resolution but mine). This is more of a “If you want to look at the code and see how to do it” than anything else. It’s available in my misc hg repository.

A particular reason you might want to look at the code is that it uses QT Jambi rather than Swing, so if you want a Swing version you’ll have to write it yourself and might find this a useful starting point. Why? Well, two reasons. Firstly, I like the results and API of QT better than Swing’s. Secondly, Swing doesn’t work on my home PC so it would be pretty pointless for me to use it.

Hector’s Reminder Service: QT Jambi and Scala

Well, I spent a lot of today putting together the application I mentioned in my recent rant.

The program is called “Hector’s Reminder Service”. Basically it’s a taskbar reminder app. You specify a random lists of messages and their approximate frequency. It gives a little notification message (not a popup window!) on the task bar showing one of those messages about that often. You can configure as many different groups of messages as you like and they’ll be scheduled independently.

The code is available here. It’s GPLed, mostly because it depends on QT and I couldn’t be bothered to figure out the ramifications. Anything I consider reusable will be factored out into a library and released under a more moderate license. I have a few more things to sort out with it (mainly packaging) and will then release a version 0.1 of it.

Currently there’s no packaging system set up. If you want to build this you’ll need QT Jambi installed – both for the user interface file compiler and for the native libraries. It’s currently untested on anything except windows, but now that I’ve given up on Swing and switched to QT I expect it should by and large work on OSX or any X-windows setup with a compliant toolbar. No doubt there will be problems, but they should be surmountable. Give me a shout if you do want to build it and discover it doesn’t work on your platform. I’ll do my best to help.

Edit: Actually, unless you’re feeling brave you probably don’t want to build this. It depends on having Scala 2.7 and jerbil installed as well as the QT Jambi libraries. You can download a prebuilt version from http://hectorreminder.googlecode.com/files/hector.zip , but you’ll still need the QT Jambi libraries installed.

Edit 2: I can confirm that Hector does work properly under linux. You need to replace the qtjambi.jar in the lib directory with the one from your jambi install (turns out that’s windows specific. Oops). Other than that he works perfectly.

Wait, you believed them when they said "Write once, run anywhere"? That’s so cute.

So, I’m writing a tiny little application that sits in your status bar and pops up occasional reminder messages in the corner of your desktop. It uses the Java 6 desktop integration stuff. It’s not very exciting – just fun and moderately useful.

I originally wrote this for Victoria with a set of hardcoded messages, so it only needed to run on windows. It worked really well, so I thought I’d turn it into a proper application – it should only be a few hours of coding to do so.

Especially, I thought, as it should run nicely cross platform.

Ha ha. Ha.

First off, Macs are ruled out – no functioning Java 6 yet. I took a brief look at using jdic instead, but it turns out that doesn’t support macs either. Argh. So, we’re stuck with windows and linux. Ho hum.

Yeah, linux? Not so much.

First off, Swing *never* works properly under linux. As far as writing cross platform GUIs, “Write once, run anywhere” is a blatant and utter lie. If you’re using Gnome or KDE with their standard window managers, it will just about limp by. If you’re using anything else, good luck.

Anyway, I use xmonad. However I use xmonad with gnome (at least on my laptop), and this is just a status bar feature, so given that I still have the gnome status bar I was optimistic.

Nope. Looks like Swing checks the window manager name, not the availability of the status bar. It’s really great the way the Swing/AWT developers actually understand the environment they’re developing for, isn’t it? On a related note, the resulting toolbar icon looks *really bad* even when I run it under normal gnome. That’s probably just a scaling and transparency issue though. I imagine I can sort it out if I try hard enough.

I have to say, despite this the desktop integration stuff is moderately nice. It’s a great way of writing once and running anywhere that has windows and the latest version of Java installed.

Sigh.