map::slippy(n)							 Mapping utilities						    map::slippy(n)

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NAME

       map::slippy - Common code for slippy based map packages

SYNOPSIS

       package require Tcl  8.4

       package require Tk  8.4

       package require map::slippy  ?0.2?

       ::map::slippy length level

       ::map::slippy tiles level

       ::map::slippy tile size

       ::map::slippy tile valid tile levels ?msgvar?

       ::map::slippy geo 2tile geo

       ::map::slippy geo 2point geo

       ::map::slippy tile 2geo tile

       ::map::slippy tile 2point tile

       ::map::slippy point 2geo point

       ::map::slippy point 2tile point

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DESCRIPTION

       This package provides a number of methods doing things needed by all types of slippy-based map packages.

API

       ::map::slippy length level
	      This  method  returns the width/height of a slippy-based map at the specified zoom level, in pixels. This is, in essence, the result
	      of

		   expr { [tiles $level] * [tile size] }

       ::map::slippy tiles level
	      This method returns the width/height of a slippy-based map at the specified zoom level, in tiles.

       ::map::slippy tile size
	      This method returns the width/height of a tile in a slippy-based map, in pixels.

       ::map::slippy tile valid tile levels ?msgvar?
	      This method checks whether tile described a valid tile in a slippy-based map containing that many zoom levels. The result is a bool-
	      ean  value, true if the tile is valid, and false otherwise. For the latter a message is left in the variable named by msgvar, should
	      it be specified.

	      A tile identifier as stored in tile is a list containing zoom level, tile row, and tile column, in this order.  The  command  essen-
	      tially checks this, i.e. the syntax, that the zoom level is between 0 and "levels-1", and that the row/col information is within the
	      boundaries for the zoom level, i.e. 0 ...  "[tiles $zoom]-1".

       ::map::slippy geo 2tile geo
	      Converts a geographical location at a zoom level (geo, a list containing zoom level, latitude, and longitude, in this  order)  to  a
	      tile identifier (list containing zoom level, row, and column) at that level.

       ::map::slippy geo 2point geo
	      Converts	a  geographical  location at a zoom level (geo, a list containing zoom level, latitude, and longitude, in this order) to a
	      pixel position (list containing zoom level, y, and x) at that level.

       ::map::slippy tile 2geo tile
	      Converts a tile identifier at a zoom level (tile, list containing zoom level, row, and column) to a geographical location (list con-
	      taining zoom level, latitude, and longitude, in this order) at that level.

       ::map::slippy tile 2point tile
	      Converts	a tile identifier at a zoom level (tile, a list containing zoom level, row, and column, in this order) to a pixel position
	      (list containing zoom level, y, and x) at that level.

       ::map::slippy point 2geo point
	      Converts a pixel position at a zoom level (point, list containing zoom level, y, and x) to a geographical location (list	containing
	      zoom level, latitude, and longitude, in this order) at that level.

       ::map::slippy point 2tile point
	      Converts	a pixel position at a zoom level (point, a list containing zoom level, y, and x, in this order) to a tile identifier (list
	      containing zoom level, row, and column) at that level.

REFERENCES

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

KEYWORDS

       geodesy, geography, latitute, location, longitude, map, slippy, zoom

map									0.2							    map::slippy(n)