Back in March, when Fremantle SDK was released, I had ported Frets on Fire to it. Subsequent discussion made it clear that modifications were required to actually make it run on the device. I created a stripped down version which could run without the OpenGL code. This made it suitable for n900 (and even n810). But due to lack of actual device, I couldn't test it.
Fast forward 7 months. Now I have access to actual n900, so recently I went back to the FoF code. After couple weeks of getting re-acquainted with the code, I have it satisfactorily running on the n900.
Frets-On-Fire code primarily has three parts -
playing the song (loading song, computing notes, etc. uses pygame for audio),
showing the visuals (PyOpenGL+pygame code) and
handling input.
All these components are pretty involved and hard to rewrite - especially so with the audio part (I hardly have any experience in musical notes and midi files). So my priority was to get almost all of the audio code as it is. It was easy to tweak the input code - to make it suite the n900 keyboard. I bypassed the visual part completely - replaced OpenGL with simple pygame sprites. (You may get disappointed by the stark looks).
I have created a project on googlecode to host the code - maemofof. It shows all the changes I had to make, starting from the base Frets-on-Fire code from v1.3.110.
The next step is to package it nicely and push to extras-devel. There are few problems with packaging though.
I couldn't get ogg files to play through pygame. I installed the ogg-support package, but for pygame/sdl to work with it, something more is required - which wouldn't install due to broken dependencies (libsdl-mixeroggwav1.2-dev). So for now I converted all ogg files to wav. But the wav files are huge (~80MB if a single song is included as sample). That makes them inconvenient to package and they also take a long time to load (~90 seconds).
But good news is, the ball got rolling again. I hope to make some progress in coming days. If you have any suggestions, feel free to chime in comments.
I have always wondered why are there so many advanced technologies to learn to create the GUI for a software application. GUI is what we see, then if we want to design or customize it, then it should be as simple as editing an image in an Image editor. This becomes more important with the next-gen handheld devices, where the GUIs will be handled more intuitively - by fingers - rather than keyboards or mice. However the problem and its solution wasn't very apparent to me.
... until I read this post by Andre Schmidt on Clutter mailing list few months back. In his simsui project, he has designed a slider widget from an SVG image and used clutter to render its differnt parts. This little project defined the problem and solution I was looking for. I played with the simsui source code. Unfortunately, that code is written for very specific widget and had some duplicate implementation of some rendering logic.
So I decided to give a try to a generic SVG (vector graphics) based GUI framework. I looked for open source SVG rendering libraries. I chose librsvg (which is now part of the Gnome desktop) for this purpose. It took me a month to understand its internals and to extend them to fulfill my needs. I eventually got it working. I now have created a fork of that library - dubbed 'libaltsvg' - under my altcanvas project.
What I have achieved so far is complete isolation of GUI from the application logic code. I have coded two samples apps - A music player and A virtual keyboard for handhelds - using this new GUI framework. As you can see in the following demo video, the GUI look-n-fill can be changed by merely changing the input SVG filename. In this framework the app logic gets simplified as well. The code for the two apps can be found in player.c and keyboard.c.
The complete source code can be found here in altcanvas repository.
The demo above is prepared on my desktop, however I have tested these on my n810 as well. Of course, the animation effects are too much for it to handle. But it works decent at minimum frame rates. I will post packages for n810 diablo in next couple of days.
To put this in perspective: this framework lets you do on your desktop/mobile, what Adobe flash lets you do on the web (and on mobiles too) - with an added benefit of coding in C (and python or other popular languages, once I get their bindings ready). There are some closed source projects for doing vector graphics based GUIs for mobile devices (ikivo, bitflash). But I haven't found any open source initiatives so far. Let me know for sure if you have.
If you are attending OSiM or Maemo summit next week in Berlin, then look for me. I will be happy to give a demo.
Update (Sep 12): A package for trying the Inkface demo on Nokia n810 is available now. Download the .deb file. [Note that the keyboard/music player are not fully functional apps. They are proof-of-concept apps for showing Inkface GUI framework benefits.] I will be flying tommorrow afternoon for Germany. If any of you guys are in OSiM or Maemo summit, I will be glad to meet. After I come back from the trip, I will work on further improvements to this project. Till then... have fun!!!
