Mobile games development

Today, we’ll see how it’s possible to build a Flickr uploader in FlashLite using KuneriLite, geotagging our photos with the current GPS location.

You can download the current FliKun version (for FlashLite 3.0) here: FliKun_3rd_edition_unsigned.sis (please read the notes at the end of this article).

So, let’s start from the beginning.

Flickr API

To upload photos to Flickr we’ll need to use Flickr API: this way we’ll be able to authenticate the user and upload/geotag photos using its REST services, all from within our application.

First thing we should do is to setup an API key for our service, going on the request page. Here you have to fill out the application details, with special care to the authentication method we want to use: suitable choices for our needs would be both desktop and mobile application authentications:

• With the first option the user will be redirected to a Flickr page, from within our application, where he should authenticate and grant necessary permissions to our application.
• With the second option we can let the user generate a mini-token from a dedicated page, using his desktop browser, and then tell him to insert this mini-token within in our application.

In both cases, we will get a token that will be used for all future uses of our application, so there would be no more need to authenticate the user after the first time.

KuneriLite Plugins

In our application, we will need to access these functionalities:

• Retrieve photos stored in phone’s gallery
• Make thumbs to show them in our application
• Start the GPS and retrieve user’s current location
• Upload stored photo on Flickr server

So, we’ll need to use the following KuneriLite plugins:

• GPS: we’ll use the start command to start GPS, and the read command to read current location
• File: with dir command we’ll be able to list files in phone’s gallery folders. We’ll use this also to store textual infos, like the user token
• Upload/Download: with this plugin we’ll upload the photos to Flickr website, using its API, and create the thumbs (with the resize command) to show them within our application

Get a token

We’ll use the desktop authentication method, so these are the steps required to authenticate the user, and to get his token:

• Get a frob, with the Flickr flickr.auth.getFrob method
• Generate the desktop authentication URL with the given frob
• Send the user to the generated URL, using the phone browser, where he should authenticate and grand permissions to our application
• When the user is back to our application, we will finally get his authentication token with the flickr.auth.getToken Flickr method

All these Flickr API calls need to be signed with an api_sig parameter, that is explained here: Flickr Authentication API page (in the Signing paragraph). To generate it in our FlashLite application, we’ll use the following function:

function getApiSignature(args:Object)
{
	var authSig:Array = new Array();
 
	for(var key:String in args)
	{
		authSig.push(key + args[key]);
	}
	authSig = authSig.sort();
 
	var apiSig:String = this._md5.hash(<API_SECRET> + authSig.join(''));
 
	return apiSig;
}

where <API_SECRET> is the API Secret associated to your API Key (you can see both of them on Flickr API Keys page).

If all has gone well, we will finally get the user token, that we must store somewhere (for example using SharedObject, or within a local file using KuneriLite file plugin).

Show phone gallery photos

Since we’ll use S60 3rd edition phones, we’ll search for photos in these folders: “C:\Data\Images\” and “E:\Images\”. Since on these phones photos will be stored in many subfolders, we’ll search within them, using “/s” argument within KuneriLite dir call. Also, we should avoid listing photo thumbs, that are stored
in subfolders named “_PAlbTN”, so it’ll be easy to spot out and avoid to get them.

Once we have the photo paths, we can use the KuneriLite resize command to resize them to our preferred size, and use those thumbs within our application. In doing this, we should care for the following points:

• It’s not possible to load more than 5 resources at once, so we should generate and load thumbs in a progressive manner, otherwise we will have lost calls (without any feedback or exception) within our application
• While loading a thumb in a MovieClip, we should take care not to remove the Clip while it’s loading (for example, because the user has navigated to another screen). Doing this we’ll avoid the issue described here.

Enter photo details and upload it!

Once the user has selected a photo, we should let him enter photo data (title, description and tags), and then let him choose if he wants to tag with his location the photo itself.

In this case, we can use the approach described in this other article to retrieve the current GPS location: Displaying gps position in flashlite using google static maps and kunerilite.

Once we have the GPS location coordinates, we can finally upload the photo to Flickr website with the upload API. Since the upload API itself requires, apart from the file itself, to send the other params within the POST body, we should use some sort of server proxy, since KuneriLite upload command does not allow to post them this way. What we could do is to send the textual parameters within the upload URL, and then let our proxy POST them to Flickr server.

Get FliKun!

This first release of FliKun is very (very!) alpha, so try it at your own risk jokes apart, there are still many points open (like the horrible graphics!), so expect new versions as soon as I’ve got the time to work more on it!

Download FliKun_3rd_edition_unsigned.sis (for FlashLite 3.0).

Currently known issues/bugs are:

• Sometimes upload fails, especially when using some special characters
• There is no upload progress bar (but will be added very soon)
• File upload fails (with error code -4) when photo size is bigger than approx 450 Kb (I’m currently working to solve this)

For any other bugs you may encounter, please leave comment on this post! Thanks

Finally note that, to use the GPS feature, you’ll need to sign the SIS file with a valid certificate.

Yesterday I’ve finished 2 projects developed using FlashLite 3.0 in conjunction with KuneriLite. Now, it’s time for some considerations.

About FlashLite

My opinion: FlashLite is far from being a mature platform for mobile development. Why?

No access to native phone functionalities.

This means no GPS, no data storage (apart from text), no video/audio capture, and much more. Since one of mobile apps strengths is in its integration with the device itself, this sounds like a big limitation (but someway it’s something like first J2ME years). This could be due to a different perspective and target users/developers, but having a powerful platform like Flash being limited to casual games or screensavers looks a bit odd to me.

Odd, senseless behavior.

What happens if you try to load more that 5 resources together? They won’t load, simple.

Or want to quit your application? You can, but at conditions: user must press some key for quit to work and, even if he does, there’s the chance that the app simply won’t close.

And if a network or local resource, for example loaded via LoadVars, is not available? You’ll have a terrible popup telling the user that he has a “Problem with content: -6″, or other similar, anti-usability things.

Security encounters insanity.

Since FlashLite 3.0, there was a nice introduction, with the new player Security settings. About this there are good articles from Ugur and chall3ng3r that point out this has caused problems in having, for example, an application loading both local and remote resources. Fortunately, there are workarounds that allow to overcome some of the limitations involved in this (like using the notorious “Trusted” folder), but we’re still far from painless development

Good news under the sun.

Bill Perry from Adobe posted back, few days after the posts from Ugur and chall3ng3r, with the news that Adobe is working to solve some of the issues pointed out, and this is absolutely a welcome kind of feedback from Adobe team!

About KuneriLite

Install, plug, use.

When you must merge 2 technologies to overcome their own limitations, it’s already a pain. So, when you do it, you want simple, immediate tools, that would make your work easier, not harder. With KuneriLite you have exacly this: an easy-to-use, understand and test tool. You have an intuitive Wizard that will allow you to create, setup and SIS package all your apps, and an emulator for easy testing and debugging. This IS what we want!

Support matters!

Briefly said: KuneriLite team is fantastic! Having worked with their product for more than 2 months, I can say to be more than happy for their help and support. You can find all the infos you want on their forums an Wiki pages.

Yes, but what?

Ok, maybe you don’t know what KuneriLite is, so here’s a brief introduction: KuneriLite is a tool that allows you to access Symbian native functionalities from your FlashLite application. They (your FlashLite app and KuneriLite) will interact via simple HTTP requests, and results are returned in the classical form of key/value pairs. So said, integration with your app will be quite straightforward.

Past, present and future.

Mobile Development is currently undergoing a lot of changes, merging and shuffles.

FlashLite seems to be trying to find his way by merging with other technologies, from Java (see Jarpa) to Python (FlyerFramework) to Symbian C++ (KuneriLite, Janus, and others) and, why not, Web Runtime. Far from having a definite solution, there’s a lot to see and experiment.

And we’re here to do it

KuneriLite is a great tool to extend FlashLite functionalities adding support for native features like local filesystem read/write, camera recording, accelerometer capabilities and much more. All these without the need to have any Symbian knowledge.

Practically, you interact with KuneriLite engine via localhost calls. For example, if you want to get recursive folder listing starting from current application base path, you can simply do:

loadVariables("http://127.0.0.1:1001/Basic/file?
klCommand=dir&klPath=\\&klArgs=/s", targetMc);

Their tool comes with an integrated wizard and an emulator, to be used with Symbian S60 3rd edition SDK Maintenance Release, to allow full development without the need of a real device.

Now they’ve just released 0.9.6.1 version, that fixes issues with Flash Lite 3 and add new cool features, as you can read on their blog, and it’s more than ever worth a try!

I’ve recently faced a tedious issue with MovieClipLoader and its loadClip method and finally realized its root cause thanks to this post on Jesse Warden’s blog.

What happens is this: if you start loading a clip via loadClip(), and then, before it finishes, you remove the target MovieClip, FlashLite (noticed the same behavior in both FL2.x and FL3.0) will raise a “Unable To Load Data” error. That’s absolutely senseless and, above all, you have no ways to catch this error and avoid the horrible popup to… popup.

So, what’s the solution? Easy: do not remove MovieClips while you’re loading something within them!