Android Question Parse KML Polygones, Save, check if inside?

[mw71]

Hello

I want to parse a KML file with polygons (XML2MAP ?) and save it (in a SQL file, or is there a more suitable way?)

Then the user should be able to check if he is within the boundaries of one of these polygons (areas).
The position of the user is provided by the GPS.

Is this possible?

 

[Erel]

Yes, it is possible. Yes, you should use Xml2Map.

 

[José J. Aguilar]

Do you need this or do you need something different?

Geofence - Monitoring a region in the background

Geofencing is an Android feature that allows your app to be notified when the user enters or exits a monitored region. The nice thing about this feature is that your app doesn't need to run for monitoring to work. It will be started automatically when needed. The GeofenceService uses...

www.b4x.com

 

[mw71]

Hi,

José, thank you, but unfortunately not.
"Geofence regions are defined as a circle with a center point and radius"
My areas are polygons, like this example http://dagik.org/kml_intro/E/polygon.html, but more Points, 2D....

the idea is to have a list of polygons and check if the (GPS) position is inside one of these polygons.

 

[roumei]

I use this code to check whether a point is inside a polyon:

Type ePoint(X As Double, Y As Double)

Public Sub IsPointInPolygon(polygon() As ePoint, X As Double, Y As Double) As Boolean
    Dim result As Boolean = False
    Dim j As Int = polygon.length - 1
    For i = 0 To polygon.length - 1
        If polygon(i).Y < Y And polygon(j).Y >= Y Or polygon(j).Y < Y And polygon(i).Y >= Y Then
            If polygon(i).X + (Y - polygon(i).Y) / (polygon(j).Y - polygon(i).Y) * (polygon(j).X - polygon(i).X) < X Then
                result = Not(result)
            End If
        End If
        j = i
    Next
    Return result
End Sub

Taken from here: c# - Is point inside polygon? - Stack Overflow

You'll have to check whether it works with lat/lon values. I use projected coordinates in UTM or other coordinate systems.