Here's an implementation that one of the OpenStreetmap applications uses: https://josm.openstreetmap.de/browser/josm/trunk/src/org/openstreetmap/josm/data/coor

Here's an implementation that one of the OpenStreetmap applications uses: https://josm.openstreetmap.de/browser/josm/trunk/src/org/openstreetmap/josm/data/coor/QuadTiling.java https://josm.openstreetmap.de/browser/josm/trunk/src/org/ope... It used to use a linear list of points, but it was VERY slow to draw, so I hacked this in to the code base a few years ago.