Getting a Polygon from a Location

Last updated: 6/14/2023

Some locations in MapsIndoors can have additional polygon information. These polygons can be used to render a room or area in a special way or make geofences, calculating whether another point or location is contained within the polygon. If a MPLocation has polygons, these can be retrieved using:

val geometry: MPGeometry = location.geometry
when (geometry.iType) {
    MPGeometry.TYPE_POINT -> {
        val point = geometry
    }
    MPGeometry.TYPE_POLYGON -> {
        val polygon: MPPolygonGeometry = geometry as MPPolygonGeometry
        // Using GMS helper classes
        // Get all the paths in the polygon
        val paths: List<List<MPLatLng>> = polygon.gmsPath
        val pathCount = paths.size
        // Outer ring (first)
        val path = paths[0]
        for (coordinate in path) {
            val lat = coordinate.lat
            val lng = coordinate.lng
        }
        // Optional: Inner rings (holes)
        var i = 1
        while (i < pathCount) {
            val hole = paths[i]
            for (coordinate in hole) {
                val lat = coordinate.lat
                val lng = coordinate.lng
            }
            i++
        }
    }
}

As demonstrated above, a polygon's outer ring/path as well as holes are arranged as [longitude, latitude] pairs. As not all locations has polygons, the polygon array may be empty. On the contrary, some locations, like entire building floors, might have more than polygon.

Developing on the new Arm-based Apple Silicon (M1) Macs requires building and running on a physical iOS device or using an iOS simulator running iOS 13.7, e.g. iPhone 11. This is a temporary limitation in Google Maps SDK for iOS, and as such also a limitation in MapsIndoors, due to the dependency to Google Maps.

Note: Due to a bug in CocoaPods it is necessary to include the post_install hook in your Podfile described in the PodFile post_install wiki.

let polygons = MPGeometryHelper.polygonsForLocation(location : MPLocation)
let polygon = polygons.first
let path = polygon.path
let holes = polygon.holes
for coordinate in path {
    let lat = coordinate[1]
    let lng = coordinate[0]
}