First steps with Maemo 5 SDK - Stardict

It looks like there is a lot of hype about new N900. I don't think I'll be able to afford one for myself but there are still people who will need a dictionary program while they are offline.

4 hours spent to get the first working binary. And there is a huge amount of work to do:

• read Maemo 5 HIG doc
• change the layout of potentially everything as all the buttons are HUGE now and previous useful area got shrinked.
• work around the bug "Xephyr crashes on clicking any editable area". Hate to have compiled/make_installed thing in my system.
  

And, of course, a screenshot:

Python surprises - scope of variables

Yesterday while debugging one place in some function I found one "surprise" in Python - language that I thought was designed to avoid surprises as much as possible(Principle of least astonishment).

if 1 == 1:
    print dir()
    found = True
    print dir()

print dir()
print "found:", found

Output:

['__builtins__', '__doc__', '__file__', '__name__', '__package__']
['__builtins__', '__doc__', '__file__', '__name__', '__package__', 'found']
['__builtins__', '__doc__', '__file__', '__name__', '__package__', 'found']
found: True

As you would have guessed coming from C++, here we had variable used out of its scope. But in Python variables live in special dictionaries - one is global where global variables and other stuff are stored and another one is local, for keeping local symbols inside the function. So all variables you create inside "for" loop or "if" scope will be stored in that local dictionary and will only be removed from there when Python's garbage collector decides.

That surprise cost me 30 minutes of wondering why some polygons on a map suddenly went nuts and lost their shapes :)

Nice feature of snprintf()

Hi all,

Yesterday I learned a feature which I'm sure should be described in every C book. To be honest, 'man snprintf' describes it as a part of C99, but I've never read the article completely.

Often when you construct a string using 'snprintf()' you need to allocate enough space for the buffer. But it's not possible to know how much you may need, so usually we just do something like this:

char buf1[1024];
/* or */
char *buf2 = malloc(1024);

which is not correct even if you are 100% sure that you string is just a "Hello world". Btw, you are wasting your stack space in first example.

So the trick here is to call 'snprintf()' twice:

int len = 1 + snprintf(NULL, 0, "%s, %s\n", "Hello", "world") ;
char *buf = malloc(len);
snprintf(buf, len, "%s, %s\n", "Hello", "world");

snprintf's behavior in C99 is to allow buffer to be NULL, but return number of bytes that would have been written to buffer. Note, second parameter should be zero too :)

Yandex plugin for Maemo mapper

After patching maemo-mapper application to support Yandex maps Max Lapan, their employee suggested his script that worked as CGI script and converted mmapper's links to yandex's ones. That was really awesome idea as there is no need to update application and contacting its developer all the time, we can just run script on 127.0.0.1 and pass parameters like city ID and x/y/z to it. Note, that Yandex is not that simple as other map vendors - there is no world map with all cities on it. Each city has its own ID and its own set of dimensions - Xs,Ys of upper left and bottom right corners of each rectangle. So I think we(interested people from Russia and Ukraine) will have to create list of supported cities with verified set of dimensions and IDs. So each city will have it's own repository in maemo mapper(see screenshot below).

I'm open to discussions about this implementation as GPS and other features are unlikely to work seamlessly and road traffic service is currenly unsupported. It's not possible to add it without patching maemo-mapper itself. But for me and probably for other people map is the most important feature.

How to setup a new repository:
URL for the map is "http://127.0.0.1:8000/?map=NUMBER&layer=1&x=%d&y=%d&z=%d"
where NUMBER is a special code for each city(Kiev=1600, Moscow=2000, St.Petersburg=500, and so on)
Download Zoom Steps: 1
View Zoom steps: 1
Downloadable zooms: min: 6, max: 14

So then we may download map for offline use as usual. I use 11,9,7 zoom levels + 6 for city center. It's about 50mb on a flash. It's better to move data file from "/home/user/MyDocs/.documents/Maps" to somewhere at /media/mmc* and create a symlink instead.

Python script can be downloaded following this link. To run simply put it somewhere in home dir and:

$ python yandexmap.py

Roadmap for the script:

1. Configuration file with a set of cities, dimensions, etc...
   
2. deb package in extras repository
3. install file on http://maemo.org/downloads unless I receive too many complaints about how stupid my script is.
4. Easy way of running script - probably it will be launched by maemo-mapper's .desktop shortcut and killed when mmapper exits.
   

Screenshots(clickable):

Maemo mapper + Yandex maps

Guys, I need map!

After googling for Maemo mapper format I found only this very useful link at internettablettalk with the list of supported servers. But unfortunately it's not that simple for us, Ukrainians. Google Maps does not have streets map even of our capital, Kiev. Russian yandex's map service is still the best, but its format is not that simple as google's:

Yandex Maps:
http://maps.yandex.ua/map.xml?mapID=1600&mapX=%d&mapY=%d&scale=%d
http://maps.yandex.ua/map.xml?mapID=1600&mapX=3397917&mapY=6491641&scale=4&slices=1

mapsID - city's id(from the set of cities)
mapX/Y - special coordinates in wild format:
Map is a 2^31 2-D array, coordinates are central point + shift * 2^(zoom level+8)

Google Maps:
http://mt.google.com/mt?x=%d&y=%d&zoom=%d
http://maps.google.com/?ie=UTF8&ll=50.352471,30.256348&spn=4.052146,12.44751&z=7

Very simple: long, lat and zoom :)

That's why is not that simple with Maemo mapper.

May be in a few days I'll test and polish what I got now and create special .deb package for Yandex-only mapper, because there are some changes now which break all other map repositories.

Below is a screenshot(click to see 800x480) of what's working at the moment. To be continued!

Labyrinth - bugfix release

It was too early to release the first version of Labyrinth without proper checking. Even considering "alpha" status of the project. The issue was found almost immediately, though I did not have a time to fix it.

Pygtk in OS2008 and in SDK 4.0 does not support method `to_string` for gtk.gdk.Color, only attributes: "pixel", "red", "green" and "blue". The method is used to store RGB color values like 127/64/0 in hex text "#007f0040000". Can someone advise why it's not working on maemo? The web site says "This method is available in PyGTK 2.12 and above.", however OS2008 contains:

>>> import gtk
>>> gtk.ver
(2, 14, 0)

This was the workaround for the issue:

def color_to_string(color):
 return "#00%02x00%02x00%02x" % (color.red, color.green, color.blue)

Now as the saving is fixed the only porting task left is maemo's Virtual Keyboard support ;)

Labyrinth - mindmap tool for maemo

Hi all!

Short preamble at first. Recently I've become a fan of mind mapping. I visited Exception #07 developers conference in March and there was a guy who did his presentation using not well-known tools like MS PowerPoint or OpenOffice Impress but he used totally different approach, Mind Map. It's the way of brainstorming or displaying your ideas just the way like human brain works - not one by one like sheets of paper but radially with multiple links and forms. It's much better than scrolling page by page during workshop, for example.

For daily use my choice was Java-based Freemind - big, but powerfull and available for Linux, Mac and less popular systems like WinXP, etc . But I wanted something small and modest to use on my Nokia N800. So I've done some search and found nothing. So I(as python/bit C/C++ dev) did some search among apps written in python and found Labyrinth - http://code.google.com/p/labyrinth/

Really don't understand people who use tons of autotool/autoconf code + python script just to install 10 .py files. But I've finally managed to release an alpha-quality port of Labyrinth for maemo - http://labyrinth.garage.maemo.org/ , available also on maemo website - http://maemo.org/downloads/product/OS2008/labyrinth/

Note! It's not ready yet for `production` as I took dev/trunk version from
the original website to have more powerful application with curves and
more export formats supported. If you are interested and want to contribute
either to application itself or to maemo port in particular - you know now where to go.

Here is what it looks like:

Back to 80s - console pacman game

Some time ago I had an interview for AI developer and the task was to write a Pacman game. I was not in mood to create a nice GUI or pretty 2D/sprites graphics, the main thing to do was to show ghosts running after the player. Used a standard non-blind path-finding algorithm for this. Here is the screenshot of the game(it's ugly, I know!):

Actually that's not the first game I've ever made. The first one was "Mine Sweeper" written in BASIC when I was 14. And I can assure you python is just awesome! May be anyone can remember GOTO and GOSUB/RETURN operators. Now having all these OOP, exceptions, libraries it's like damn nightmare. I definitely will prefer python to BASIC when teaching my children ;)

The source code(in python, of course) can be found following the link

Stardict port for IT OS2008

Finally did something useful for Open Source. It's 1:00AM now and I've just completed compiling everything I could find for my Nokia N800. Installing maemo chinook SDK was not without confusing things but I hope they will fix everything.

So the first application was of course Stardict. Just few fixes to code from trunk and it's ready:



Thanks to Gonzo for hosting. You can find 2 deb packages following this link. I'll commit my changes during next few days. In my To-Do list I have now Freeciv, my pacman game and mplayer's new GUI.