B4J Question Find screen X, Y, of Google Map

Roger Daley

Well-Known Member
Licensed User
Longtime User
Hi All,

I am trying to find the screen XY of a Google map. In B4A I use the GoogleMapExtras library functions:
Projection1 = GoogleMapsExtras1.GetProjection(gmap)
ScreenPosition = Projection1.toScreenLocation(MarkerLocation)
    BTSX = ScreenPosition.X
    BTSY = ScreenPosition.Y

The only problem is that there is no JGoogleMapExtras.

As always, any help much appreciated.

Regard Roger


B4X founder
Staff member
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Longtime User
This code works and is based on the only method available:
Sub gmap_Click (Point As LatLng)
   Dim xy() As Double = LatLonToXY(Point)
   Log($"x = $1.2{xy(0)}, y = $1.2{xy(1))}"$
End Sub

Public Sub LatLonToXY(ll As LatLng) As Double()
   Dim jo As JavaObject = gmap
   jo = jo.GetFieldJO("map").RunMethod("getProjection", Null)
   If jo = Null Then Return Array As Double(-1, -1)
   jo = jo.RunMethod("fromLatLngToPoint", Array(ll))
   Return Array As Double(jo.RunMethod("getX", Null), jo.RunMethod("getY", Null))
End Sub

I'm not sure how these values refer to the screen.
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