GPS service for android and suggested changes in Necessitas.

[Frameworks]

Hi,

On more thing? How the load library problem gets fixed in Experimental?

Thanks,
Carlos.

On 06/02/2011 03:10 PM, Frameworks wrote:
> Hi,
>
> No problem.
>
> I am working on the GPS mobility plug-in (giving that there is a way 
> of having the JObject of the current activity running the QT 
> application).
>
> Cheers,
> Carlos.
>
> On 06/01/2011 09:53 PM, BogDan wrote:
>> Hi,
>>
>>
>> Please accept my apologize for slow replay.
>>
>>> ________________________________
>>> From: "frameworks at qlands.com"<frameworks at qlands.com>
>>> To: necessitas-devel at kde.org
>>> Sent: Sunday, May 29, 2011 10:58 AM
>>> Subject: GPS service for android and suggested changes in Necessitas.
>>>
>>>
>>>
>>> Hi,
>>>
>>>
>>>
>>> First of all. Thanks for the brilliant work!.... Running QT in 
>>> Android is just mind-blowing!
>>>
>>>
>>> I just joined the list of developers to contribute to the project. 
>>> Just after I got a copy of Necessitas 0.1 I had to see how to make 
>>> the GPS work. I wanted to implement it as most as possible with JNI 
>>> and with the minimum of java code.
>> Great, we have something in common :)
>>
>>
>>>   From a GPS example written in Java 
>>> (http://hejp.co.uk/android/android-gps-example/) I got that the main 
>>> challenges were:
>>> 1- To implement the LocationListener interface
>>> 2- To connect to the location manager by 
>>> Activity.getSystemService(service)
>>> 3- To request the locations using the Listener by 
>>> LocationManager.requestLocationUpdates(gps provider, double, float, 
>>> listener,looper)
>>>
>>> This main challenges arose from two main constraints:
>>> 1- The LocationListener is an interface so needs to be implemented 
>>> in a class in a very basic way. Thus I had to include such 
>>> implementation as part of the industrius java classes:  
>>> QtGPSListener.java with the following implementation:
>>>
>>> package eu.licentia.necessitas.industrius;
>>>   import android.location.Location;
>>> import android.location.LocationListener;
>>> import android.location.LocationProvider;
>>> import android.os.Bundle;
>>>   public class QtGPSListener implements LocationListener {
>>>            public void onLocationChanged(Location location)
>>>      {
>>>                  // Here we get the location data and create a result
>>>                  // string (A really basic way of passing data). We 
>>> called sndonLocationChanged that is
>>>                  // in fact connected to the qt application by JNI's 
>>> registeNatives
>>>                  String accuracy;
>>>                  accuracy = String.valueOf(location.getAccuracy());
>>>                    String altitude;
>>>                  altitude = String.valueOf(location.getAltitude());
>>>                    String latitude;
>>>                  latitude = String.valueOf(location.getLatitude());
>>>                    String longitude;
>>>                  longitude = String.valueOf(location.getLongitude());
>>>                    String res;
>>>                    res = "|AC:" + accuracy;
>>>                  res = res + "|AL:" + altitude;
>>>                  res = res + "|LA:" + latitude;
>>>                  res = res + "|LO:" + longitude + "|";
>>>                    sndonLocationChanged(res);
>>>      }
>>>              public void onProviderDisabled(String provider)      {
>>>                  String res;
>>>          res = "Provider " + provider + " is disabled";
>>>          sndonProviderDisabled(res);
>>>      }
>>>              public void onProviderEnabled(String provider)      {
>>>                  String res;
>>>          res = "Provider " + provider + " is enabled";
>>>          sndonProviderEnabled(res);
>>>      }
>>>              public void onStatusChanged(String provider, int 
>>> status, Bundle extras)      {
>>>                  switch (status) {
>>>          case LocationProvider.OUT_OF_SERVICE:
>>>              sndonStatusChanged("Status Changed: Out of Service");
>>>                            break;
>>>          case LocationProvider.TEMPORARILY_UNAVAILABLE:
>>>              sndonStatusChanged("Status Changed: Temporarily 
>>> Unavailable");
>>>                            break;
>>>          case LocationProvider.AVAILABLE:
>>>              sndonStatusChanged("Status Changed: Available");
>>>                            break;
>>>                  }
>>>        }
>>>          // List of methods that will be linked in the qt application
>>>          // using JNI's registerNatives
>>>          public static native void sndonLocationChanged(String 
>>> currLocation);
>>>          public static native void sndonProviderDisabled(String 
>>> message);
>>>          public static native void sndonProviderEnabled(String 
>>> message);
>>>          public static native void sndonStatusChanged(String message);
>>>       }
>>>
>>> 2- I had to use the activity running the qt application so I can 
>>> use  getSystemService(String). I though there were some Android API 
>>> to get an instance to the current activity running (so I can use JNI 
>>> to get it) but it seems that there is none.
>> Actually it is, QtApplication.mainActivity()
>>
>>
>>> So the only alternative that I had was to pass the activity from 
>>> QtApplication.java to qtmain_android.cpp. For this I made the 
>>> following changes:
>>>     2.1 -  In QtApplication.java: FROM: public static native void 
>>> startQtApp(String params,String env) TO: public static native void 
>>> startQtApp(String params,String env,Object currAct)
>>> 2.2 - In qtmain_android.cpp: FROM: static jboolean 
>>> startQtApp(JNIEnv* env, jobject /*object*/, jstring paramsString, 
>>> jstring environmentString) TO: tatic jboolean startQtApp(JNIEnv* 
>>> env, jobject /*object*/, jstring paramsString, jstring 
>>> environmentString,jobject currAct)
>>> 2.3 -  In qtmain_android.cpp: I created a jobject currActivity = 
>>> NULL that I can extern in my sample application. Plus assigning it a 
>>> global reference of the current activity:  currActivity = 
>>> env->NewGlobalRef(currAct). This to use it in JNI thread of execution
>>>
>> Hmm :)
>>
>>
>>> With this changes I create a QT GPS class with JNI code that access 
>>> the GPS. I just need to pass it the JavaVM that I extern from  
>>> qtmain_android.cpp and  currActivity.
>>>
>>>
>>> I can see that in 0.2 necessitas include QtLocation.java  (which 
>>> implements the GPS). Although it is fine, I reckon it is better to 
>>> implement much of that code in the c++ side with JNI and only have 
>>> the minimum java code just for implementing interfaces for example.
>>>
>> Agree with you !
>>
>>
>>> This is an snapshot of the QT GPS class where it connects to the 
>>> service
>>>
>>>
>> [...]
>>
>>> To conclude. A JNI implementation of the Android GPS service with 
>>> very basic java code will require to have a Jobject pointing to the 
>>> current activity running the QT application.
>> Please call QtApplication.mainActivity() to get it !
>>
>>
>>> This I reckon would make a Mobility plugin less dependent on 
>>> external java coding.
>> It will be great, because the java part can't be updated, by Ministro 
>> service !
>>
>>
>>> But where it would be the best place to implement this change? I 
>>> made it on qtmain_android.cpp and qtApplication.java but for a  
>>> Mobility plugin this might not be the case.
>>>
>> Please change current Mobility implementation ! You'll get Java_vm 
>> pointer when the plugin is loaded by application and 
>> QtApplication.mainActivity() is a static function which can be used 
>> to get current activity.
>>
>>
>>> I register myself on gitorious. For contributing do I need to work 
>>> on a clone of master?
>>>
>> Please clone 
>> http://qt.gitorious.org/~taipan/qt-mobility/android-qt-mobility and 
>> use testing branch !
>>
>>
>>>
>>> Thanks a lot for the brilliant work!
>>>
>>>
>>>
>> Thanks,
>>
>> I'm looking forward to hearing from you
>>
>> Cheers,
>> BogDan.
>>
>>
>> Again, sorry for slow replay.
>>
>>
>