Class WebMercator

java.lang.Object
com.codename1.maps.vector.WebMercator
public final class WebMercator extends Object

Spherical Web Mercator (EPSG:3857) helpers expressed in "world pixels" -- the slippy-map coordinate space where the whole world spans tileSize * 2^zoom pixels. All of the vector engine's panning and tile math is done in this space.

These are the standard OSM tiling formulas; kept here (rather than reusing the projected Mercator) so the renderer can work in fractional pixels at fractional zoom without round-tripping through the legacy Coord projection flag.

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    static final double
    MAX_LATITUDE
    The furthest latitude Web Mercator can represent.
    static final int
    TILE_SIZE
    The canonical tile edge length in pixels.

  • Method Summary

    Modifier and Type
    Method
    Description
    static double
    centerLatitude(double southLat, double northLat)
    The latitude that sits visually halfway between southLat and northLat on a Mercator map -- the midpoint of their projected y coordinates, converted back.
    static double
    clampLatitude(double lat)
    Confines lat to the range the projection can actually represent.
    static double
    latToWorldY(double lat, double zoom)
    Latitude in degrees to an absolute world-pixel y at zoom.
    static double
    lonToWorldX(double lon, double zoom)
    Longitude in degrees to an absolute world-pixel x at zoom.
    static double
    sinh(double x)
    Hyperbolic sine, absent from the minimal device Math.
    static double
    worldSize(double zoom)
    The world width/height in pixels at zoom (may be fractional).
    static double
    worldXToLon(double worldX, double zoom)
    World-pixel x at zoom back to longitude in degrees.
    static double
    worldYToLat(double worldY, double zoom)
    World-pixel y at zoom back to latitude in degrees.

    Methods inherited from class Object

    clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Field Details

    • TILE_SIZE

      public static final int TILE_SIZE
      The canonical tile edge length in pixels.
      See Also:

    • MAX_LATITUDE

      public static final double MAX_LATITUDE
      The furthest latitude Web Mercator can represent. The projection runs to infinity at the poles, so every slippy map cuts off here, which also makes the world exactly square.
      See Also:

  • Method Details

    • worldSize

      public static double worldSize(double zoom)
      The world width/height in pixels at zoom (may be fractional).

    • lonToWorldX

      public static double lonToWorldX(double lon, double zoom)
      Longitude in degrees to an absolute world-pixel x at zoom.

    • latToWorldY

      public static double latToWorldY(double lat, double zoom)
      Latitude in degrees to an absolute world-pixel y at zoom.

    • worldXToLon

      public static double worldXToLon(double worldX, double zoom)
      World-pixel x at zoom back to longitude in degrees.

    • worldYToLat

      public static double worldYToLat(double worldY, double zoom)
      World-pixel y at zoom back to latitude in degrees.

    • clampLatitude

      public static double clampLatitude(double lat)

      Confines lat to the range the projection can actually represent.

      Projecting a latitude beyond MAX_LATITUDE produces an enormous or infinite y, and arithmetic on those values quietly yields nonsense: averaging the projections of -90 and 90 lands on the south pole rather than the equator. Clamping first keeps every derived camera finite and sensible.

    • centerLatitude

      public static double centerLatitude(double southLat, double northLat)

      The latitude that sits visually halfway between southLat and northLat on a Mercator map -- the midpoint of their projected y coordinates, converted back. Both inputs are clamped to MAX_LATITUDE first.

      This is not the arithmetic mean, because Mercator stretches distances away from the equator. Latitudes 0 and 80 average to 40, but their projected midpoint is about 57; centering a camera on 40 pushes the northern edge of that band well outside a viewport sized to hold it. Anything framing bounds must center this way for the fitted zoom to actually contain them.

    • sinh

      public static double sinh(double x)
      Hyperbolic sine, absent from the minimal device Math.