Tag: open source

Hello Android!

By Ashish Datta | 6 Comments on Hello Android!

In the last few weeks the battle and buzz over the smart phone market seems to have seriously intensified.

First there was the usual iPhone buzz, news about the Android powered HTC Magic, the Windows Mobile marketplace, and of course the obligatory ridiculousness at Microsoft.

I’d been considering experimenting with a mobile platform for sometime and finally decided to take the plunge. I decided to give Android a whirl primarily because I don’t have easy access to OSX or Visual Studio and my Java is less rusty than my .NET.

Anyway, getting going with Android was deliciously simple – download the SDK+Emulator and Eclipse plugin and you’re off.

After the necessary “Hello World” application I tried to write something a bit more substantive. Personally, one of the coolest facets of mobile development is the ability for applications to be location aware (GPS). Mix this together with some openly available geo tagged data and the result is probably going to be interesting.

With this in mind, the plan became to mash together Android’s GPS coordinates with flickr’s geotagged photos.

Getting access to Android’s location service is fairly straightforward. You basically register to receive updates either when the device moves a certain distance or on some time interval:

The biggest “gotcha” with this is that you NEED to remember to modify the default Application security settings to allow you to access the device’s location. In Eclipse, edit AndroidManifest.xml and add “UsesPermission” for the following: android.permission.ACCESS_MOCK_LOCATION, android.permission.ACCESS_COARSE_LOCATION, android.permission.ACCESS_FINE_LOCATION

So on to part II – using the device’s location to pull down Flickr photos. I’d used the Flickr API before so I knew how to do it but I’d never used it from Java. I tried loading the JAR for the flickrj client library but the Android JVM was having some strange issues with it. I was under the impression you can link to external JARs from Eclipse but I may be wrong (anyone?).

Anyway, the Flickr requests were un-authenticated and pretty straightforward so I decided to use Java’s URL class. Accessing sockets was another “gotcha” – Android requires your application to have the “UsesPermission” android.permission.INTERNET to use sockets. The exception when the permission isn’t set is notably cryptic – “unknown error”.

I decided to download all the Flickr photos to the device so that the UX would be generally smoother. This introduced threading to the project so that the UI wouldn’t freeze up while the photos were downloading. Android threads work just like traditional Java threads and the process was generally painless:

With the photos pulled down the final task was displaying them. After poking around the Android documentation I discovered the Gallery widget. It basically allows you to display a set of items in a list and specify a “renderer” for the gallery. I’m not sure if there is a default way to make it “fisheye” (like on an iPhone) but I rolled a quick n dirty solution for that. I also couldn’t get it to look really sexy but that’s also probably possible.

So that’s about it. Here are some screen shots of the application running in the emulator:

And without further a due here is the code as an Eclipse project.
geoflickr

Anyway, before the bashing starts – I know I’m a terrible Java programmer and that this project isn’t really engineered beautifully. It was just supposed to be a way to get my (and anyone else’s) feet wet with Android. Any comments/thoughts/improvements are of course welcome!

Client-side validation for the new Symfony forms with jQuery

By Hamid Palo | 3 Comments on Client-side validation for the new Symfony forms with jQuery

The new Symfony forms are great improvement over the old forms and once you get over the learning curve you can’t imagine life without them. The only problem with them is that they don’t really offer client-side validation (yes, being agnostic when it comes to Javascript libraries is maybe good but come on). There is fortunately a plugin that does client-side validation but it is Prototype-based, and looks a bit clunky.

For those of us using jQuery there was nothing, so we decided to write our own small helper that integrates this jQuery validator with the new forms. It’s nothing fancy, but it does the trick for now, and we may expand it into a full-fledged plugin that does all sorts of crazy things.

Using the helper:

  1. Download and install the jQuery validation plugin.
  2. Download the helper and put it in lib/helper/jQueryValHelper.php
  3. Include the jQueryVal helper.
  4. To enable the helper for a specific form:
    <?php echo jquery_val_form_tag($form, array(‘action’ => url_for(“@register“) ))?>

That’s it.

The validator currently supports email, min and max length validation. The only required option is action, the other options you can pass it are:

  1. error_placement: Change where the errors are rendered, for example:
    'error_placement' => 'error.prependTo(element.parent().next())'
  2. error_element: Change the element used to render the errors, default is label.

All other options you pass are added to the form as attributes.

JSON explorer for Firebug!

By Ashish Datta | 1 Comment on JSON explorer for Firebug!

As Firefox plugins go, Firebug is definitely one of my favorites. It has saved me and the rest of the Setfive team dozens of development hours. One of the nicest features of Firebug is the NET panel. The NET panel allows a developer to monitor HTTP requests that Firefox is making during the course of a page’s execution. This is particularly useful to AJAX heavy applications because it allows a developer to easily debug XHR requests and responses.

Although this is great, the NET panel is severely lacking when it comes to dealing with JSON responses. Since JSON must be a legal JavaScript string, it can’t contain any line breaks. As a consequence, debugging long JSON strings is extremely painful.

This issue has been on the Firebug TODO list for some time. I figured this would be a good place to jump into the Firebug codebase. I dropped an email to the Firebug working group and received some great feedback. Honza gave me a template extension to extend the NET panel and provided some great insight and advice on implementing a JSON viewer.

After a couple of weeks of intermittent work, the JSON-Viewer extension is ready to play with. Honza has committed the code into the Firebug 1.4+ branch so if you grab a new build you’ll be able to use the JSON viewer.

Screenie:

Read more at Honza’s blog post