I participated in GSoC for Go OpenOffice, which is a project that maintains a set of patches on top of OpenOffice. Go OpenOffice is the OpenOffice version distributed with OpenSuSE, Ubuntu and other distros, it is allegedly a lot better than the official OpenOffice release. And also available for Windows.

Hacking OpenOffice have been a very exciting experience. I haven’t worked on a project so large and complex before. It easily takes 2 hours to build OpenOffice and the sources and binaries fills about 13 GiB. Luckily I didn’t have to rebuild everytime I had to test something.

The visual formula editor, see video above, is not production ready yet. That is it needs extensive testing and a few extra features… However, I plan to keep working on it. You can read more about it’s features and current status here.

I don’t think I’ll keep updating that wiki page, but rather post some updates here once in a while. If you are eager to help test this feature when it comes that far, feel free to leave a comment with your email…

This semester my group have designed and implemented a small statically typed object oriented language slightly inspired by Python. We wrote our own lexer and parser generator in Python, and implemented the compiler in C++. And just for the record we implemented the DFA of the lexer and PDA of the parser using goto’s, inspired by re2c, this was quite fun and the result very fast.

The language is called groo (that was the best name we could come up with), it compiles into gril (groo intermediate language) which in turn run on VROOM (groo virtual machine) where memory is managed by MOM (Mark-sweep Object Manager). Whilst this isn’t the best project yet, and all the acronyms doesn’t make much sens, I really like to say that when we need to release memory we call MOM to clean up
(I appoligies for my crazy sens of humor).

I don’t think the project is of much use to anybody else… But if you want to play with simple, well documented compiler in C++, this might be it… Also the parser generator is AFAIK pretty unique, haven’t see anybody else implement a parser using goto’s… Anyway the project report and groo compiler source code is all in English and available here:

• Project report (1.5 MiB PDF)
• Compiler source code (16,5 MiB tarball)

• Project page
• Git repository

By the way did I mention, git is really nice… I just had a little fun making a bugfix branch and merging it…

I’ve found the patterns applicable many places, and recently had the privilege of using one in my C# programming exam. I previous mentioned this book when I discussed “Framework Design Guidelines“, which I wasn’t too happy about at the time… However, “Design Patterns” is definitely the book for writing reusable code, whereas “Framework Design Guidelines” is more concerned with the usability of the APIs.

Anyway, that was a word on “Design Patterns”, definitely worth a read…

The result is bindings for a subset of ZBar and a Gtk# bar scanning widget. I don’t intend to maintain the source, but if you find any bugs etc. or wish to start a project for the bindings, please leave a comment…

• zbar-sharp documentation
• Download zbar-sharp

The example application using the bar code scanning widget can be seen on to right. Note: this was a really lousy webcam . The check-mark appears when a bar code have been recognized and then fades away.

In Foodolini we used HAL to detect webcams as they were plugged, however, having heard that Ubuntu will be deprecating HAL, I didn’t care to clean up the source for this feature. If you interested it can be found in the source for Foodolini. And if anybody should happen to know how to detect webcams, distro independently, without HAL, please leave a comment…

Anyway, I needed a MusicPlayer module that would make it easy to publish music in Flash based music player, so I wrote one. The documentation for pluck is fairly good, php on the other hand is horrible (it took me a while to figure out I had to enable error reporting). Nevertheless, the result allows the user to upload mp3s, choose player skin and settings. For playback I used Xspf Jukebox which has 20 skins included some of which are fairly good looking…

You can download the module here… It’s for pluck 4.6, tested with 4.6.3.

Update: This plugin is now hosted at github: github.com/jopsen/pluckplayer.

While writing a backend for Pwytter I also created some abstractions for micro-blogging services, so that Pwytter supports multiple accounts and multiple services (currently Twitter and Identi.ca). With this new backend all the messages are also cached in an sqlite database, enabling Pwytter for work while offline.

I also added theming support to the Qt frontend I wrote for Pwytter, above is a screenshot of Pwytter running the “Twitter-like” theme (as you can see have also be translated, so far only to Danish). Pwytter uses WebKit to display tweets, users and other types of content, thus themes can customize the GUI using HTML templates and Qt stylesheets. Documentation for writing such themes can be found in the project wiki, I plan to write an article on subject when this Pwytter branch is released. So far this Pwytter branch is still under development, and interested developers can find install instructions in the project wiki.

A few months ago I felt like I needed to get better at writing clean reusable code, so I impulsively bought a book called Framework Design Guidelines, Conventions, Idioms, and Patterns for Reuable .NET Libraries. Now having read the thing I must admit that I found large parts of it rather boring. The book is mainly presented in “Do”/”Do not” form, however, interrupted by annotations that discusses these guidelines, and gives examples to where these are followed or forgotten in the .Net Framework.

Apart from the annotation this book is mainly about usability of .Net libraries, conventions and guidelines for the public interface of a .Net library. This book only briefly touches a few design patterns, but apart from these it’s all about the public interface and how to design this in order to facilitate extensibility. So if you’re look for coding guidelines on how to design the public interface for a .Net library this is the book. However, I was probably a bit to impulsive, so I’ll be reading Design Patterns next…

The report discusses what the demand for ray tracing is, what ray tracing is and how a ray tracer can be implemented, covering the basics of ray tracing and bounding volume hierarchies. It also discusses how distribution could be done, which is the only slightly new thing in it… It’s not a perfect report there’s still some areas where the English is kind of bad and some sections that could use a rewrite or two
Nevertheless, considering the circumstances I’m satified the result. And the group have worked fine…

Now the interesting part, TheMatrixDistributed, as a part of this project we implemented a distributed realtime ray tracer, with bounding volume hierarchies, spheres, planes and triangles that supports textures. We also did a small obj parser to import models exported from Blender. TheMatrixDistributed is implemented in C++ and it’s turned out to be quite fast, considering that the rest of my group have little to no programming experirence. When distribution to 6 dualcore laptops and a quadcore desktop we got around 8 FPS at best with 1024×768 screen and about 100,000 triangles in the scene, not filling the entire screen.

The frontpage image (original 1024×768) seen above has about 1,000,000 triangles it was render on 6 dualcore laptops and a quadcore desktop at about 0.6 FPS with 4x antialias.

Though the report and TheMatrixDistributed probably isn’t of much value to anybody it’s published here if anybody should be interested. The report is released under Creative Commons Attribution-Noncommercial-Share Alike 2.5 and TheMatrixDistributed is released under GNU GPL.

• Realtime ray tracing distributed (twoside)
• TheMatrixDistributed (source and binaries)

Derfor har jeg fornyeligt anskaffet mig en Lenovo Thinkpad R500, med 2 GiB ram, 250GB harddisk, dualcore 2 processor og 1600×1050 i skærmopløsning, sidste nævnte skal man vende sig lidt til… Verden er jo blevet næsten 4 gange så stor

Da jeg fik den, havde den en fin Windows Xp installation der fyldte hele harddisken og havde de omkring 70 fuldstændigt totalt uundværlige baggrundsprocessor kørerende. Jeg formoder at ironien er tydeligt, det tog mig i hvertfald ikke ret langtid at få lukke ned for det skidt. Så prøvede jeg om jeg kunne få system gendannelses partitionen til at lave partitioner og gendanne, men fandt ikke uden videre ud af hvordan man skulle gøre det… Hvis man da kan det…

Det lykkedes mig dog, uden størrer problemer at installere Ubuntu 8.10 på PC ved at formatere fuldstændigt. Jeg var dog så betænksom at efterlade en lidt plads til en Windows partition, hvilket jeg nu har installeret fra VirtualBox Jeg har ikke prøvet at boote den uden for VirtualBox, og tvivler også lidt på at den vil samarbejde…