Code to offset Android Google Map positions in pixels.

MapAdjust.java

// MapAdjust.java

// Based on adjust.py
// Gatubit <gatubit@gmail.com>
// https://gist.github.com/astrocosa/724526

// Based on adjust.js
// Bratliff <bratliff@umich.edu>
// http://www.polyarc.us/adjust.js

import com.google.android.gms.maps.model.LatLng;

public abstract class MapAdjust {
    private static final double OFFSET = 268435456;
    private static final double RADIUS = OFFSET / Math.PI;

    public static LatLng xyToLL(int x, int y, LatLng latLng, int z) {
        return xyToLL(x, y, latLng.longitude, latLng.latitude, z);
    }

    public static LatLng xyToLL(int x, int y, double lon, double lat, int z) {
        double resultX = xToLon(
            lonToX(lon) + (
                x << (21 - z)
            )
        );
        double resultY = yToLat(
            latToY(lat) + (
                y << (21 - z)
            )
        );
        return new LatLng(resultY, resultX);
    }

    private static long lonToX(double lon) {
        return Math.round(OFFSET + RADIUS * Math.toRadians(lon));
    }

    private static long latToY(double lat) {
        return Math.round(
            OFFSET - RADIUS * (Math.log(
                (1 + Math.sin(Math.toRadians(lat)))
                /
                (1 - Math.sin(Math.toRadians(lat)))
            )) / 2
        );
    }

    private static double xToLon(double x) {
        return Math.toDegrees(
            (Math.round(x) - OFFSET) / RADIUS
        );
    }

    private static double yToLat(double y) {
        return Math.toDegrees(
            Math.PI / 2 - 2 * Math.atan(
                Math.exp((Math.round(y) - OFFSET) / RADIUS)
            )
        );
    }
}