Class ZoomLevelFunction

  • All Implemented Interfaces:
    FunctionExpression, Factory, Expression, Function

    public class ZoomLevelFunction
    extends FunctionExpressionImpl
    Function that takes a scale denominator and a srid and outputs the zoom level.

    Note: EPSG:3857 is currently the only supported srid, and zoom levels are assumed to be at the equator.

    Example:

     ff.function("zoomLevel",
                   ff.function("env", ff.literal("wms_scale_denominator")),
                   ff.literal("EPSG:3857")
                );
     
    The above function would evaluate to the zoomLevel that corresponds to the current environment's wms_scale_denominator, for EPSG:3857.

    Example 2:
     ff.function("zoomLevel",
                   ff.literal(136494.693347),
                   ff.literal("EPSG:3857")
                );
     
    The above function would evaluate to a zoomLevel of 12.
    • Field Detail

      • ROOT_TILE_PIXELS

        public static final int ROOT_TILE_PIXELS
        Number of pixels in the side of the root tile. Assumes 512 if not otherwise configured.
      • EPSG_3857_O_SCALE

        public static final double EPSG_3857_O_SCALE
        Scale denominator of the root tile. Changes based on the ROOT_TILE_PIXELS value.
    • Constructor Detail

      • ZoomLevelFunction

        public ZoomLevelFunction()
    • Method Detail

      • getArgCount

        public int getArgCount()