This year I was invited to organize a workshop at the Mobile 2.0 Open Ideas event at Barcelona, on 16-17 June. With my experience developing Android apps at Mobialia and the social media integration on Martin Varsavsky’s RadioMe, I proposed the workshop:

Bulding Social Media Enabled Android Apps

This will be a 1-hour . . . → Read More: Mobile 2.0 Open Ideas]]>

This year I was invited to organize a workshop at the Mobile 2.0 Open Ideas event at Barcelona, on 16-17 June. With my experience developing Android apps at Mobialia and the social media integration on Martin Varsavsky’s RadioMe, I proposed the workshop:

Bulding Social Media Enabled Android Apps

This will be a 1-hour workshop In which I’ll provide some examples on how to integrate social media on Android apps, from the simple “Share” button to more complex integrations like using Twitter, LinkedIn or Facebook APIs, including logging-in with social media, etc.

I will try to do it interesting for developers and also for app designers who want to add cool social features to their apps. Slides and code samples will be available from the day of the event.

• Mobile 2.0 Open Ideas
• Building Social Media Enabled Android Apps at Mobile 2.0

For me it was easier to implement Twitter API access using only the signpost library, for facebook they recommend to download their Android SDK, and I did so. First we . . . → Read More: A small problem with the facebook Android SDK]]> At Mobialia the lasts weeks I was involved on the development of a social app using, among other social networks APIs, the facebook API.

For me it was easier to implement Twitter API access using only the signpost library, for facebook they recommend to download their Android SDK, and I did so. First we need a class attribute with the Facebook object:

Facebook fb = new Facebook(appId);

The problem is during the autentication process: we must call the fb.authorize method…

fb.authorize(this, PERMISSIONS, ACTIVITY_CODE, this);

And wait for the result of this called activity on our onActivityResult method


protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    fb.authorizeCallback(requestCode, resultCode, data);
}

But, here is the problem, under heavy memory requierements (like testing on a old HTC Magic) the caller activity may be killed, and the status of the Facebook object is not maintained so the call to authorizeCallback is going to fail.

Then I need a method to mantain the Facebook object status, and here comes the hack. I added this method to the Facebook object:

public void setStatus(int mAuthActivityCode, DialogListener mAuthDialogListener){
    this.mAuthActivityCode = mAuthActivityCode;
    this.mAuthDialogListener = mAuthDialogListener;
}

And I call this method on my onActivityResult:

protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    fb.setStatus(ACTIVITY_CODE, this);
    fb.authorizeCallback(requestCode, resultCode, data);
}

Note that the DialogListener is the same Activity. Other solution may be to avoid killing of the caller activity, but I don’t figure how…

This location methods can be enabled or disabled by the user on the preferences or with some widgets.

Initially on our apps we used . . . → Read More: Using two location providers on Android]]>
Android has two kinds of accuracy on location:

• Fine: provided by the GPS, needs some time to be obtained
• Coarse: location determined with the cell of the mobile network

This location methods can be enabled or disabled by the user on the preferences or with some widgets.

Initially on our apps we used only one LocationProvider with “Fine” accuracy:

• If the GPS was disabled it used automatically network-based location
• But if GPS was enabled, the location used it needing some time to be determined

As the data couldn’t be obtained until the location is determined, the app didn’t showed data, receiving this kind of error reports from some users.

The best solution that I found is to mantain two separated providers, with different precisions and receive location updates using both.

LocationManager manager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
Criteria criteria = new Criteria();
criteria.setAltitudeRequired(false);
criteria.setBearingRequired(false);
criteria.setCostAllowed(false);
criteria.setPowerRequirement(Criteria.POWER_LOW);       

criteria.setAccuracy(Criteria.ACCURACY_FINE);
String providerFine = manager.getBestProvider(criteria, true);

criteria.setAccuracy(Criteria.ACCURACY_COARSE);
String providerCoarse = manager.getBestProvider(criteria, true);

if (providerCoarse != null) {
    manager.requestLocationUpdates(providerCoarse, 5*60000, 100, this);
}
if (providerFine != null) {
    manager.requestLocationUpdates(providerFine, 5*60000, 100, this);
}

You can also check if providerFine and providerCoarse are the same provider. When receiving location, the one received from providerFine must take precedence over the one from providerCoarse. Location’s provider can be obtained with location.getProvider():

public void onLocationChanged(Location location) {
     if (location.getProvider().equals(providerFine)) {
     ...

This is a trick that we are using on our Gas Stations Spain app and also on Wikiplaces (open sourced).

I developed a special app for this event called “Wikiplaces” and I made the code avaiable as open source on Google Code.

This app shows on a map or on a list places from Wikipedia near your location. . . . → Read More: Mobialia at LabAndroid]]> This week I was speaking at LabAndroid, a spanish initiative about Android devices, apps and development.

I developed a special app for this event called “Wikiplaces” and I made the code avaiable as open source on Google Code.

This app shows on a map or on a list places from Wikipedia near your location. I tried to include on it small code snippets for common things like styles on layouts, obtaining location, launching Google Maps Navigation, etc.

• Source on Google Code
• Page and Slideshow
• Article on and.roid.es

The event started with Dave Burke presenting Google Technologies in general. Many jokes about the iPhone (to show the Chrome2Phone . . . → Read More: Google DevFest 2010]]> As many of you know, this year I’m involved on Android with my project Mobialia. On February I was on the Android Developer Lab at Madrid and today I returned for the Google DevFest.

The event started with Dave Burke presenting Google Technologies in general. Many jokes about the iPhone (to show the Chrome2Phone extension he send a page about iPhone unlocking from Chrome to a Nexus One). He made the typical Sunspider Javascript Test comparation between a Nexus One with Froyo and an iPad. It also was quite impressive so see GWT Quake2 Port running on Chrome at 50 FPS and the new voice/camera input fields on HTML5.

Then the sessions where split on two lines, I assisted to the Android, Chrome&HTML5 and Maps related.

Our beloved Reto Meier was speaking at the Android Sessions, much more technical than on February’s Android Developer Lab (good!). On his first session he made a great presentation about good and bad practices developing Android Apps (I suggest every android developer to see it!), on the second he speaked in detail about Cloud to Device Messaging and vice-versa. He gave me lots of app ideas using this feature. Finally he swowed us proudly his new Samsung Galaxy Tab and encouraged us to adapt our applications to the new tablet devices.

There were also very short presentations of spanish app developers (eAdventure, LibreGeoSocial, Inmobilia, Sicad and great the one of AnderWeb!).

Next, Paul Kinlan speaked about Chrome Apps and Extensions, the App Store and HTML5 on detail. I’m also very happy to see the progression of HTML5 and how Chrome is leaveraging the innovation towards a better web. Quite funny to see a modified Pacman Doodle controlled with the acceleromers of the iBook. There was also a presentation of Fiabee showing their HTML5 app and Chrome extension.

On the last sessions with Josh Livni talking about maps and presenting the Google Maps API v3, I was very impressed with maps customization, Fusion Tables and the new Google Street view API possibiliting the creation of 360º photos and adding them on specific locations (as inside a bar!).

All the sessions where recorded on video and will be avaiable at the Google DevFest Madrid web site.

First of all I decided to leave Negamax and go with Principal Variation Search (PVS). Also decided to implement separate methods for root . . . → Read More: Tales of a chess engine developer]]> Chess engine development is one of the most brain-crushing activities I’ve been involved on the last years. Last nigths I was working again on my Carballo Chess Engine with some advances.

First of all I decided to leave Negamax and go with Principal Variation Search (PVS). Also decided to implement separate methods for root nodes, PV nodes and null window searches. On previous experiments PVS was performing worse than Negamax, but I discovered the reason: the aspiration window has some implementation issues with PVS: when the search for a move fails low at the root node the move must be researched enlarging the window.

I was very stranged of why Futiliy Pruning was not working for me, but finally discovered the reason: a simple sign change after evaluation was the reason! Also implemented to store the evaluation values on the Transposition Table (TT).

The next step: why Carballo searched much less depths than other engines, it was due to quiescence search. I was generating checks for the first 4 PLY’s of quiescence, but some other engines not, so this was the reason. I decide to generate only checks on the first PLY of quiescence and only for PV nodes. Also modified a bit the move generation to optimize for quiescence.

During this time also found many interesting bugs, I was storing on the TT the bound and not the score when failing high/low, also on PV nodes is better to use only the TT for ordering and not to return scores from it, this helps avoiding draws. Also found a serious bugs involving time management (was taking as reference opponent’s time) and with contempt factor on IID searches corrupting TT entries. Finally added a Pawn Push Extension and removed the Recapture Extension and now some extensions now depend of the node type.

Running some test tournaments, I hope to get some good results soon and add the improved engine to my Mobialia Chess.

Jim Ablett has published a packaged executable for my Carballo chess engine. He also made a pretty logo for it, shown here. Check his page to download executables for Carballo and a lot of other chess engines: Jim Ablett’s Winboard Chess Page. Thanks Jim for your great . . . → Read More: Jim Ablett’s Carballo packaging]]>

Jim Ablett has published a packaged executable for my Carballo chess engine. He also made a pretty logo for it, shown here. Check his page to download executables for Carballo and a lot of other chess engines: Jim Ablett’s Winboard Chess Page. Thanks Jim for your great work!

GWT is provided from Google to develop applications in Javascript programming in Java. It conterts the Java code to Javascript, and the application is run on . . . → Read More: Great GWT UI for Carballo Chess Engine]]> Lukas Laag has written me about his new  GUI for the Carballo Chess Engine  using the Google Web Toolkit (GWT) and his SVG Graphics Library for GWT, libgwtsvg.

GWT is provided from Google to develop applications in Javascript programming in Java. It conterts the Java code to Javascript, and the application is run on the browser, without any additional plugin.

This interface is quite better than the sample Applet from Carballo, it has move history, legal move hightlighting, and SVN graphics. It can be used from:

http://www.vectomatic.org/gwt/libgwtsvg-chess/libgwtsvg-chess.html

He also wrote an article explaining the difficulties of his project. Thanks Lukas for your work.