Last week I’ve attended to GStreamerConf and LinuxConf conferences in Prague, and Siraj and I had the honor of having our current project for Collabora exposed on Collabora’s both. It shared space with two others amazing Collabora‘s demos:

1. Media Explorer running a Telepathy plug-in, which adds IM and Audio/Video capabilities to the system.
2. HTML 5 client of a video editor, using GStreamer Editing Services on top of GtkWebkit.

A little bit about Telepathy Webkit Client

During the last few weeks I’ve been working on a Telepathy client, a very special one, written almost only with HTML 5 and Javascript, on top of GTK WebKit and Seed.
The goal of this project was writing a Telepathy based IM client, to run on top of WebKit, and it should be able do make and receive audio and video calls.

GObject introspection magic

The first question to be answered was “How access the Telepathy methods from Javascript?”

And the answer was: GIR and Seed.

As all Gnome developers knows, GObject introspection (GIR) allows us to access a GObject written in C  from a scriptable language, such as Javascript. So that’s part of the answer.

And Seed binds those introspected objects on WebKit JavascriptCore, which is pretty much what we wanted to do.

Following a few screen-shots

Contact List

Our first goal was to show the Telepathy’s roaster list on a HTML5 window. For the widgets, we choose to use joApp, which is a quite nice and stable UI library for HTML 5 applications.

Chat Window

What’s a IM client without a Chat window, right?!

The “tpwebkit” application with an opened text channel between two users.

Receiving a call

Telepathy WebKit application acting as a Telepathy approver for audio and video calls

That’s me, from the point of view of my test machine…

The real thing running

If you want to see the real thing running, you can watch this video showing the application during the early development state.

Conclusions and future work

As we can see from now, Telepathy is ready to be use on native and HTML applications.
I really would like to see the current implementation integrated with the bleeding edge RTC API, which some guys are pushing to WebKit. That would be something really awesome.

If you want to try it, you can get the code here and play with it. You’re also going to need a few special changes on Seed package. Check the linuxconf branch here.
Or, if you use Ubuntu, you can add Xavier’s PPA and install the tpwebkit package.

With a little help of Ademar, we’ve selected a good use case: a bouncing game.

The game

The flags

The flags I want to comment on this post are:

• QGraphicsScene::ItemIndexMethod
• QGraphicsView::OptimizationFlags
• QGraphicsView::ViewportUpdateMode

The results

* Those tests were performed on a Nokia 5800, type RM-356, with V51.0.006 firmware and Qt 4.6.3.
** The Y axis is measuring FPS: the higher, the better.

10 elements on the screen

First of all, I’ve tried the four ViewportUpdate methods, with 10 items on the screen, and the MinimalViewportUpdate and the SmartViewportUpdate gave me the highest FPS( 34 and 33.5) . Qt documentation shows NoIndex as the best option for dynamic scenes… well, the difference is small for few items, but it’s true =)

So, for the other tests, lets use the NoIndex flag.

What about optimization flags?

I took two results from the latest test (SmartViewportUpdate and BoundingRectViewportUpdate) and ran it again with two optimizationFlags: QGraphicsView::DontSavePainterState and QGraphicsView::DontAdjustForAntialiasing. So, optimizations flags brings us a little bit of improvement when we can control precisely how the items will be drawn.

20 elements

30 elements

40 elements

Lessons Learned

It’s important to select the correct ViewportUpdate method for your kind of scene. It can make the difference.

If there is a lot of dynamic elements, and if they are scattered throughout the scene, it’s cheaper to paint the whole screen (or, at least, the bounding rect) instead of trying to determinate the affected area.

To be honest I was expecting a better result from FullViewportUpdate, but I believe it would be better than BoundingRect if we use non-static background.

What if?

What if I use only one graphicsItem to paint all the balls? What if a ball was not an item but an object with a render method?

I got a little bit surprised, it wasn’t the result I was expecting – it’s worst. It only gets to be better when I put more than 60 items on the screen.

Will I throw the code in the garbage can?

No! As the result of the tests and with a creative help of Nara – INdT designer – I’m releasing a playable alpha version of this game, called by Chubba-Lubba. It’s not finished, since it’s still missing the icon, sounds and scores features, but it’s testable =)

Symbian package here!

First: KDE 4.2 was released. I’m using as my “oficial desktop manager” at work and I’m pretty happy about it.

Second: Debian Lenny might be released this month.  I’m using it too, and I know the result will be very good!

Third: BossaConference agenda is ready. Think about great minds talking about OpenSource, Maemo, etc, in a paradisaical beach. I had the opportunity to join Bossa ’07, and it was great! We can’t miss this one! See you there! =)

I’m not having much time to work on my personal projects ( pychord by example ) cause I’m having a lot of tasks to do ( and to learn ) on my college and on my new job.

But I’m here to talk about pychord, so let me do it! =)

Tim wrote a lot of good suggestions on garage’s foruns. So, I’m working on their ideas now. I need to say “thanks” to Tim cause he gave me a lot of good suggestions to make pychord better. Thank you Tim!

On this last weekend I worked in “Zoom IN/OUT ” feature and change the font of the chord’s screen. I think that pychord is a little better now.

You can get it here, or do a “upgrade” on your device.

That is all!

Have a nice week!

All features (about 1.0 version) are working. Now I need to work in two different lines.

• Source Code improvement [1]
• Bug Fixes[2]

[1] I didn’t have enough knowledge about pygame when I started this project. So I need to change some parts of the code to fix wrong decisions that I made before.
[2] If you are using this application, please, give me a feedback and I will try to make it better!

Then I will start to develop the 1.1 version ( with some features that I promised before ).

In this version, I created a configuration file (/home/user/.pychord.conf), and this file has to have two simple lines:

db=/home/user/.pychord.db
datadir=/home/user/pychord/data

Where:
“db” is your DataBase file, with all your chords. Its a sqlite’s file.
“datadir” is the folder where pychord will get the chords to put into database file on update process.

You can edit these options by clicking on “i” symbol in PyChord’s first screen. You can also choose by what type of update you want: Full-update or Incremental Update. In Full-update you will lose all your database data. In incremental update pychord will get all files of your datadir and put into database.

All files in your datadir folder have to have the “.chr” extension, and have to be like this example:

Name: Music Name
Artist: Music Artist Name
D# E F
Your chords
D # E F
Your chords
D E# F
Your chords

(Two first lines are used like headers, describing the Name of the music and the name of the Artist. Followed by the chords)

Ok, its too easy right?!

So, you have to have a directory (datadir) and put all your files there. Default folder is /home/user/pychord/data. Don’t forget to update your database when you start to use this application.

So, Ok! Now you can download .install here!

If you have problems to install this application, try again by searching for it on ApplicationManager->Browse Installable Applications->others->pychord

If you have any problems after that (or suggestions), please, let me know!

[]‘s