NAME

       map::slippy::fetcher - Accessing a server providing tiles for slippy-based maps

SYNOPSIS

       package require Tcl  8.4

       package require Tk  8.4

       package require img::png

       package require map::slippy

       package require map::slippy::fetcher  ?0.4?

       ::map::slippy::fetcher fetcherName levels url

       fetcherName levels

       fetcherName tileheight

       fetcherName tilewidth

       fetcherName get tile donecmd

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DESCRIPTION

       This  package provides a class for accessing http servers providing tiles for slippy-based
       maps.

API

       ::map::slippy::fetcher fetcherName levels url
              Creates the fetcher fetcherName and configures it with the number  of  zoom  levels
              supported by the tile server, and the url it is listening on for tile requests.

              The result of the command is fetcherName.

   METHODS
       fetcherName levels
              This  method returns the number of zoom levels supported by the fetcher object, and
              the tile server it is accessing.

       fetcherName tileheight
              This method returns the height of tiles served, in pixels.

       fetcherName tilewidth
              This method returns the width of tiles served, in pixels.

       fetcherName get tile donecmd
              This is the main method of the fetcher, retrieving  the  image  for  the  specified
              tile. The tile identifier is a list containing three elements, the zoom level, row,
              and column number of the tile, in this order.

              The command refix donecmd will be invoked when the fetcher either knows  the  image
              for  the  tile or that no image will forthcoming.  It will be invoked with either 2
              or 3 arguments, i.e.

              [1]    The string set, the tile, and the image.

              [2]    The string unset, and the tile.

              These two possibilities are used to either signal the image for the tile,  or  that
              the tile has no image defined for it.

REFERENCES

       [1]    http://wiki.openstreetmap.org/wiki/Main_Page

KEYWORDS

       http, location, map, server, slippy, tile, url, zoom