Android Question [SOLVED] Get GPS coordinate of a point shown on an OpenStreetMap panel

adrianstanescu85

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Hello

I added an OpenStreetMap map inside a panel, which is working fine, and what I would need is to know the GPS coordinates (lat, long) of a certain point I'm specifying inside that panel.

Let's say the panel is 400 x 200 px, and I'd need to find out the GPS coordinates of the point shown inside that panel at 100 x 40 px at the current zoom level.

Does anyone know how to do that?

Thank you!
Adrian
 

adrianstanescu85

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Yes, I'm using OSMDroid 3.0.8. Can you point a short example please? So far I wasn't able to find one, maybe I looked in the wrong places so far.
Thank you!
 
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adrianstanescu85

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Inline java would do well too... for now converting to 4.1 might be pretty troublesome in the time left on the telemedicine project I'm working on. If you could pass a few inline java lines just for this map projection it would help a lot! Thank you!
 
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warwound

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Ok it actually looks quite simple...

This is the inline java you need to add to any Activity that you need to use it in:

B4X:
#If JAVA
import org.osmdroid.util.GeoPoint;
import uk.co.martinpearman.b4a.osmdroid.util.wrappers.GeoPointWrapper;

public GeoPointWrapper FromPixels(org.osmdroid.views.MapView mapView, int x, int y){
	GeoPointWrapper wrapper=new GeoPointWrapper();
	wrapper.setObject((GeoPoint) mapView.getProjection().fromPixels(x, y));
	return wrapper;
}
#End If

And your b4a calling code should look something like:

B4X:
Dim NativeMe As JavaObject
NativeMe.InitializeContext

Dim GeoPoint1 As GeoPoint=NativeMe.RunMethod("FromPixels", Array As Object(MyMapView, XCoord, YCoord))

' now test if GeoPoint1 is correct

Martin.
 
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adrianstanescu85

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I put the inline java at the end of the activity
Also put the NativeMe declaration in Process_Globals.
Set the InitializeContext in Activity_Create when ran the first time.
In the mean time the map was well working as already set.

I set a label with a LongClick event get the geopoint and then list the coordinates.

This is the error I'm receiving: "An error has occured in sub:amedicsef_labelpressscena_longclick (java line: 946) java.lang.ClassCastException: uk.co.martinpearman.b4a.osmdroid.util.weappers.GeoPointWrapper cannot be cast to org.osmdroid.util.GeoPoint Continue?"

Why could this happen?
 
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adrianstanescu85

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The exact code is:
B4X:
Sub LabelPressScena_LongClick
    Dim GeoPoint1 As GeoPoint  =NativeMe.RunMethod("FromPixels", Array As Object(MV1, 50, 50))
   
    ToastMessageShow("Lat: " & GeoPoint1.Latitude & " ,Long: " & GeoPoint1.Longitude, False)
End Sub
where MV1 is a MapView object. Thought this might help.
 
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warwound

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Try this:

B4X:
#If JAVA
import org.osmdroid.util.GeoPoint;

public GeoPoint FromPixels(org.osmdroid.views.MapView mapView, int x, int y){
	return (GeoPoint) mapView.getProjection().fromPixels(x, y);
}
#End If
 
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