Updates from June, 2011 Toggle Comment Threads | Keyboard Shortcuts

  • pit 3:46 pm on June 30, 2011 Permalink | Reply
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    Calculate and show a route on Ovi Maps with Java ME Location API 

    After the article showing how to geocode an address with the help of Java ME Location API, today it’s time to explore the routing functionality offered by Ovi Maps.

    This new article covers the main aspects involved in calculating and showing a route on a map, by allowing the user to navigate through the maneuvers of the calculated route.

    The full article with source code and a downloadable MIDlet is available on Nokia Developer Wiki: How to calculate and show a route with Java ME Location API.

     
  • pit 12:45 pm on June 29, 2011 Permalink | Reply
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    Java ME and Ovi Maps: geocoding an address with the Location API 

    The Java ME Location API allows to easily integrate Ovi Maps in a Java ME application, with just few lines of code, together with a set of ready-to-use features as geocoding and reverse geocoding, routing, positioning and more.

    I’ve recently started to publish a set of articles on Nokia Developer Wiki that show the various features of the API in action. You can read the first one here: Geocoding an address with Java ME Location API.

    Check it out and let me know your comments.

     
  • pit 12:05 pm on February 24, 2011 Permalink | Reply  

    Implementing a simple View Manager with QML 

    Today’s new QML tutorial shows how to implement a simple View Manager in QML.

    The video below shows how the component behaves on a Nokia N8 device.

    Check out the full article on Forum Nokia Wiki: simple QML View Manager.

     
    • max 9:35 am on March 30, 2011 Permalink

      Hi Alessandro,

      thank you for a really cool article. I am having problems understanding the visibleChanged signal:

      function connectViewEvents(view)
      {
      view.visibleChanged.connect(function() {
      SVM.showView(view);
      });

      where is the signal visibleChanged declared? Can you kindly explain the connect call and how it works?

  • pit 4:07 pm on February 21, 2011 Permalink | Reply
    Tags: coverflow, , qml, , , ,   

    How to build a CoverFlow component with QML 

    Today I’ve published a new technical article on Forum Nokia Wiki, that shows how a CoverFlow component can be easily built with Qt Quick and QML.

    You can see a video of the CoverFlow component in action on a Nokia N8 device below.

    The full source code is available here: Building a CoverFlow component with QML.

     
  • pit 10:20 am on March 17, 2010 Permalink | Reply
    Tags: , , , wdl, web developer's library,   

    Forum Nokia Web Developer’s Library 1.9 available 

    Forum Nokia has just updated its excellent resource for mobile Web development, the Web Developer’s Library, adding a lot of resources to support the design and development of Web Runtime widgets.

    Changes in this last release include:

    If you’re a mobile Web developer, check it out!

     
  • pit 10:35 am on February 18, 2010 Permalink | Reply
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    Deploying API Bridge apps the easy way: the delayed deploy model 

    When developing a Flash Lite, Web Runtime or Java ME application based on API Bridge, one of the things you know you’ll have to deal with is the Symbian packaging and signing process.

    For single-person and small developer teams, the whole Symbian process could be a not suitable option. For this reason, I’ve looked for an alternative deployment approach that could bypass this process. The approach presented here is based on a delayed deploy model, meaning that the API Bridge engine is not deployed with your application, but in a successive moment: actually, it is deployed only when the application needs it.

    How this can be achieved? Basically, there are 2 possible options to implement this model, and they’re based on:

    • AppManager API from Platform Services
    • Local HTTP calls

    Using the AppManager API to check API Bridge

    If the target devices support Platform Services, the AppManager API can be used to retrieve the list of installed applications, and so to check if API Bridge is installed on the device itself.

    The code below shows how this can be achieved by using JavaScript in a WRT widget. The same approach can be easily ported to ActionScript, and so used in a Flash Lite application.

    var apiBridgeFound = false;
    var apiBridgeCheckError = null;
     
    var so = device.getServiceObject("Service.AppManager", "IAppManager");
     
    var criteria = new Object();
    criteria.Type = 'Application';
     
    var result = so.IAppManager.GetList(criteria);
     
    if(result.ErrorCode == 0)
    {
    	var iterator = result.ReturnValue;
     
    	var application;
     
    	while((application = iterator.getNext()) != undefined)
    	{
    		if(application.Uid == '0x20023710')
    		{
    			apiBridgeFound = true;
     
    			break;
    		}
    	}
    }
    else
    {
    	apiBridgeCheckError = result.ErrorMessage;
    }

    The code works by checking the UID of all the installed applications, comparing them with the API Bridge UID (0×20023710). This code snipped defined 2 variables, that can be used to check for API Bridge availability:

    • apiBridgeFound: if true, it means that the API Bridge engine is installed on the device. If false, the API Bridge engine is not installed.
    • apiBridgeCheckError: if not null, it means that there was an error while checking for API Bridge, due to the AppManager API. In this case, the application cannot actually know if the API Bridge engine is installed or not.

    So, once these 2 variable have been set, the application can perform the most appropriate operation, based on the AppManager call result. The code snippet below shows a possible implementation:

    if(apiBridgeCheckError != null)
    {
    	alert("There was an error! " + apiBridgeCheckError);
    }
    else if(!apiBridgeFound)
    {
    	if(confirm("You have to install API Bridge to continue, press OK to download it"))
    	{
    		widget.openURL('http://www.yourserver.com/APIBridge_v1_1.sis');
    	}
    }
    else
    {
    	alert("API Bridge is already installed on the device!");
    }

    And below you can see this code running on a Nokia 5800 XpressMusic:

    Using local HTTP calls to check API Bridge

    Since the API Bridge engine works as a local HTTP server running on the mobile phone, the other possible approach is to make an HTTP request, and to check if any response from API Bridge comes.

    Note: this approach works by using the API Bridge default port (9080). There are no guarantees that this port number is fixed, and that it will not be changed in future API Bridge releases. For this reason, my advice would be to use this second approach only when Platform Services are not available.

    The code below shows how to make a request to the local API Bridge HTTP server, and how to check if it’s running or not: if it is running, the response status of the XMLHttpRequest object has to be different than zero.

    function pollApiBridgeServer(_callback)
    {
    	var request = new XMLHttpRequest();
     
    	request.open("GET", "http://127.0.0.1:9080", true );
     
    	request.send(null);
     
    	request.onreadystatechange = function()
    	{
    		if( request.readyState == 4)
    		{
    			if(request.status != 0)
    			{
    				_callback(true);
    			}
    			else
    			{
    				_callback(false);
    			}
    		}
    	}
    }

    The approach described here can be used also when using API Bridge from other languages, as Flash Lite or Java ME. Anyway, when working with Flash Lite, in the scenario where API Bridge is not yet installed, you will incur in the typical (and horrible) error popups, that will inform you (and so the user) that the network call failed.

    How to use the code above? First, define a callback:

    function pollApiBridgeCallback(apiBridgeInstalled)
    {
    	if(apiBridgeInstalled)
    	{
    		alert("API Bridge is already installed on the device");
    	}
    	else
    	{
    		if(confirm("You have to install API Bridge to continue, press OK to download it"))
    		{
    			widget.openURL('http://www.yourserver.com/APIBridge_v1_1.sis');
    		}
    	}
    }

    Then, just call the pollApiBridgeServer() method by passing a reference to this callback:

    pollApiBridgeServer(pollApiBridgeCallback);

    Pros and cons

    Using one of the two approaches discussed above as some important advantages over the standard API Bridge deployment mechanism:

    • You don’t have to build a SIS package
    • You don’t have to sign your application to distribute it
    • You will save money :)

    On the other side, these approaches have the main drawback on the user-experience side, since your users could be asked to download and install an additional component when they start to use your application. Anyway, this event will happen only once at most, so it could be considered reasonable in most scenarios.

     
    • Pat 4:16 am on March 1, 2010 Permalink

      Hi Alessandro , I’m trying to understand how to package/install a custom API bridge with a J2ME app. A specific post about that would be great. Thanks.

    • Diogo Moreira 2:13 pm on June 7, 2010 Permalink

      Hi Alessandro, Is there anyway to change themes phone using APIBridge by requisition for wrt ?
      I wait answer, Thanks !

    • pit 2:38 pm on June 7, 2010 Permalink

      Yes, by implementing a custom plugin you can also let a WRT widget change the device active theme. This Forum Nokia Wiki article could help for the C++ part:

      http://wiki.forum.nokia.com/index.php/TSS000456_-_Changing_the_active_theme

    • Pedro Cardoso 6:49 pm on June 25, 2010 Permalink

      Hi,

      I’m trying to use APIBridge on my app as you explain on this post, but whenever I try to do a function call (ie: retrieve the list of photos, or resize an image), the app crashes without any warning. Just quits and that’s it. The APIBridge detection is working as you outlined.

      Do you know any way I can troubleshoot, where/if any logs exist that explain the cause?

      Thanks a bunch.

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