Evas exposes just a handful object types, like solid color rectangle, gradient rectangles, images, text, text block, polygon, line and smart object.

Smart Object is the only special type because it’s extensible and developers should implement its virtual methods to have it to behave like regular objects with calls like evas_object_color_set() or evas_object_resize(). Smart Objects do not have any visual representation, they can contain other objects that may have it, like images or rectangles, that’s why they’re represented like a box in the figure above. Their children are handled as if they were in a special layer: outside objects cannot interleave smart object children. It’s recommended as good practice to not expose children to outside, instead provide methods to manipulate these children.

A regular mistake is to forget that just creating objects from inside smart object methods don’t make them children! You must assign a parent to a child with evas_object_smart_member_add(child, parent). You can “unparent” them with evas_object_smart_member_del(child). As children can not have more than one parent, adding a new parent to the child will first remove its parent before adding the new one.

Edje is a smart object that loads a group of parts from a description file often called “EDJ” (or edje file). These files contains a collection of groups, each with a set of parts (evas objects), each part with various states. When a group is assigned to some Edje object with edje_object_file_set(object, file_name, group_name) the parts are created in order (first will go first, thus will stay at the bottom) using the "default" 0.0 state. If some part have relative positioning to the whole available space (Edje object geometry), when the edje object is changed, all the dependent parts are recalculated and have their geometry set. If some part is relative to other parts, then when one of these changes, the dependent part is recalculated and reset as well. One can manipulate edje by changing the state of the parts, this should be done by means of programs, which will act based on signals. Edje will dispatch some signals like "resize", "mouse,move" and "show", but users are encouraged to create their own application signals that can be emitted with edje_object_signal_emit(object, "signal", "source").

The most common mistake using Edje is to touch its children. Never, ever, change the object that you get with edje_object_part_object_get(). That call is for inspection purposes only. You’re just allowed to change Edje by emitting signals from your application, EDJ should have programs to catch that signal and trigger some state change on some parts. Let’s remember that it’s recommended to never changed smart object children, Edje is strict, making this a rule. What can you expect if you break this rule? Before, I said that Edje would recalculate dependent parts when the dependency changes, but I lied: for simplicity purposes, when something change, Edje recalculates the whole thing, and it does so using the state information from EDJ, not the current value of the object. If you change the color of some rectangle from white to black, recalculation will enforce the rectangle to be white. Same for images, if you set the image file to be something else, it will be restored to the image specified in the EDJ.

One variation of this mistake is dealing with SWALLOW parts. These parts enable user to add an external object to be managed by Edje with the edje_object_part_swallow(object, "part_name", external_object). As said, Edje will manage this external object: it will become the object’s parent, it will set clippers, colors, visibility and geometry. After that call, user don’t own the object anymore, he is only allowed to change other, non managed properties, ie: images can have their file set because SWALLOW parts don’t have any image property (unlike IMAGE parts!)

It’s very important to understand these concepts. Real applications are a mix of smart objects and edje, one inside the other, which might led to great confusion if management ownership is not clear.

In the figure above we can see the management ownership to avoid these problems. User manages both the smart object and the background. In order to change the edje he should call some API defined in the smart object. To change the “star” image, user should call smart object that would call edje.

You can also download the printable version of the figure.

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README says:

Eet is a tiny library designed to write an arbitary set of chunks of
data to a file and optionally compress each chunk (very much like a
zip file) and allow fast random-access reading of the file later
on. It does not do zip as a zip itself has more complexity than is
needed, and it was much simpler to implement this once here.

It also can encode and decode data structures in memory, as well as
image data for saving to eet files or sending across the network to
other machines, or just writing to arbitary files on the system. All
data is encoded in a platform independant way and can be written and
read by any architecture.

This library is very stable already, with almost no change in the last years, the last addition was the “inlined strings” that are kept in their own read-only section, so you get them mmap()ed on load.

It’s the core of E17, being used to handle configuration data and Edje themes (includes images, scripts and regular data). What I find great about it is the easy- to use struct serializer/parser that you can use to save and load structured data, including lists and hash tables. And it is almost dependency-free, just: libc, libz, libm and libjpeg.

If you are a packager of some distro, or you know some, please package it. If you find out any problems, let them know, but it should be very straightforward, with Ebuild, RPM and DEB packages already available from some sites.

Funny fact: enlightenment is the project ID “2″ at sourceforge.net, the sourceforge.net project itself is the number “1″

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That’s cool because one can do lots of things (and some users are already showing us some nice plugins!), but we still need some base text introducing people to the concepts, with smaller code, so here it is: Canola URLBookmark source code and text.

This introduces you to some concepts, explains about “plugins.info” and how plugins are loaded and in the end you have a list of URL to play. Of course this hard coded list of URL is on purpose so you take some time to change it to something more useful. If you ask me, I’d like to see UPnP, MPD, Samba, Avahi, Shoutcast and lots more.. I did my part, everything you need to know is there, now it’s your turn.

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I’ll be a mentor for Enlightenment and we have great ideas, if you’re interested in them, mail me or go to #edevelop @ irc.freenode.net so we can discuss your ideas, experiences… It’s a great way to get involved in computer graphics and a platform that is growing everyday on mobile systems, with adopters like Canola2 and now OpenMoko!

As for BlueZ, I’m not mentoring, but some friends are, they also have great ideas, things that will benefit every GNU/Linux bluetooth user, from mobile to desktops to laptops, some are really interesting like better audio support. It’s a way to get into kernel and low-level user space world, and get paid for it

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Let’s hope next year we can keep it to the level! Congrats to all the organization members.

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UPDATE: Since we replaced our download manager, previous packages conflicts! Please remove Canola2-beta1 before installing the new one. If you got it wrong, apt-get -f install from Xterm should fix it.

Hope installation will be smoother this time!

More information at: http://openbossa.indt.org/canola2/

* 770 support: gregale is regular install, but for Hacker Edition (bora ported to 770) you need a special proceeding (ain’t you hackers!?):

1. disable all repositories
2. add the repositories:
   1. deb http://repository.maemo.org gregale free non-free
   2. deb http://repository.maemo.org/extras gregale free non-free
3. update list
4. install canola2
5. remove gregale repositories

These steps are required because Hacker Edition kernel doesn’t provide inotify and we compile bora EFL packages optimized for n8xx (omap 2420, arm1136jf-s).

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On the bug fixes front, after Canola2 was released and it was tested with multitude of media I could fix lots of bugs with parsers, mainly on jpeg and id3lib.

Last but not least, thanks to Renato Chencarek we now have ogg support, and I also added png and audio-dummy to register known media files we still have no specific parsers (real, wma, …)

It’s already stable, when I have time I’ll add a non-dual process version of process and check, so people with “correct” media files can use this and benefit from a much faster version (however this will rely on developers adding support to choose both implementations).

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That conference was so great that INdT is now promoting another, actually much improved:

Come and enjoy a innovative conference on Open Source Software for Mobile Embedded Platforms. Located in Porto de Galinhas, one of the tropical paradises of Brazil, the Bossa Conference will happen during 16^th to 19^th of March at Summerville Beach Resort. The perfect combination of developers, pleasant environment and good ideas.

Let’s go! We’re waiting for you.

Information and registration: www.bossaconference.org.

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Lightweight media scanner meant to be used in not-so-powerful devices,
like embedded systems or old machines.

Provides an optimized way to recursively scan directories, handling
the parser in a child process, avoiding breaks of the main process
when parsers break (quite common with such bad libs and tags).

Parsers are plugins in the form of shared objects, so it’s easy to add
new without having to recompiling the scanner.

The scanner will use SQLite3 to store file-mtime association, avoiding
parsing files that are already up-to-date. This SQLite connection and
the file id within the master table ‘files’ are handled to plugins for
relationship with other tables.

Check out the code, it’s really simple to use and write new parser plugins:

• C API
• Python API
• SVN
• GIT - LightMediaScanner
• GIT - Python-LightMediaScanner

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The actor is Kenneth, our little danish fellow.

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Our designers did this wonderful piece of work in order to us developers check what/how to do things and now they made it available to everyone so you can start to wonder how it would be to use it

As Marcelo said in his blog, this is a teaser, not the real product, so you might expect some different bits here and there, we’ll fix these issues as we find them.

Also, for those that looked at the website and thought “ah, not much compared to the previous version”, don’t understand this release as a feature release, but instead as the foundations that we’ll build upon and then release new feature releases. It was a huge amount of work to improve underlying system, rewrite everything in Pyhton, write bindings to new libraries, rethink how some things should be done.

For those Free and Open Source developers: unfortunately we’ll keep it closed for now (same talk as before), but at least much, much more of our work is open source that you can already use and benefit from our improvements: The whole graphical ui is based on EFL, media scanner is based on lightmediascanner, UPnP will be based on BRisa, video player is MPlayer…

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Today I’ve presented at CELF Embedded Linux Conference 2007, Linz, Austria, the title was “Fancy and Fast GUIs on Embedded Devices” and is now available online at http://talks.gustavobarbieri.com.br/efl/elce2007/Fancy_and_Fast_GUIs_on_Embedded_Devices.odp Maybe it’s useful to you (trying to get your managers to use something else than GTK/SDL for embedded devices?).

The conference was really great, I’ve met some great hackers that I just know from mail/IRC and could talk again with others that I already knew from other conferences. Free software hackers are usually very kind.

People’s reaction was quite positive, most people realize that trying to modify GTK to fit desired effects or building on top of SDL are both way too painful. I’m not saying that these are bad and nobody should use it, but that they have their own niche and trying to have them to cover the whole word is a bit difficult.

Related to this, Carsten Haitzler (The Rasterman) (EFL lead developer) was officially announced as “Lead Architect - Graphics” at OpenMoko, a previously GTK-only device. He will not vanish with GTK, but instead create nice native applications, full of special effects and so, that’s cooperation, each technology doing their best to achieve the final goal: usable interfaces.

UPDATE: Video (OGG/Theora) is now available:  http://free-electrons.com/pub/video/2007/elce/elce-2007-gustavo-sverzut-barbieri-fast-fancy-gui.ogg, http://video.google.com/videoplay?docid=-2292516949813732934&hl=en

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We already have to work on missing infrastructure bits, having us to work around these technical hardware problems is no fun!

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Apple has invested no money to create a public development infrastructure, community resources and not even a cross compiler toolchain. Actually, they tried hard to avoid people writing native applications, but even with these factors they got to the point they have more useful (IMO) applications than N800, with Nokia creating Maemo, funding scratchbox, tons of resources to improve Gnome and related tools.

Sure, they already ship with great apps by default, as an excellent media player and browser and simple but good enough mail client, maps, PIM… but you can already install game emulators that works (I’m talking about on screen controls, due multi-touch) and even some web applications through Python/Django. See some apps at http://iphoneapplicationlist.com/.

Although there is no documentation on HIG or even widget API, these applications look integrated, they benefit from graphical/physics effects, support screen rotation and more, and if you consider the timeline, it is 2 months old and the cracks to install home brew software is even newer!

I still have no conclusion on what we did wrong and they right, but IMO things are more favorable for them. Maybe it’s about they touching the hackers egos (forbidden is always cool), maybe it’s about better infrastructure, … What’s your opinion?

PS: the device is neat, things seem well integrated, they did just the simple things, but did they right, really. Their attention to details, not just for user interface, is incredible.

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The plan was to do it in less than one week, it took a bit more since I had to work on other things, fix some bugs with the EFL itself and also implement new features (like pointer_mode: NOGRAB) and also did the initial graphics, later replaced with Ian’s nice work. It does no type prediction, word hint, cursor navigation or key composition (accents are not possible).

Summary is 230 lines of Python, 1110 lines of Edje, including comments and blank lines, and a really easy to type keyboard.

• N800 version: easy install, repository: http://www.gustavobarbieri.com.br/e17-n800/ bora free
• Keyboard code: SVN http://barbieri-playground.googlecode.com/svn/efl-tests/vkbd/

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