# NAME

Geo::Coordinates::GMap - Routines for converting decimal lat/lon to Google Map tiles, and back again.

# SYNOPSIS

``````    use Geo::Coordinates::GMap;
my (\$tile_x, \$tile_y) = coord_to_gmap_tile( \$lat, \$lon, \$zoom );
my (\$new_tile_x, \$new_tile_y) = zoom_gmap_tile( \$tile_x, \$tile_y, \$old_zoom, \$new_zoom );
my (\$x, \$y) = gmap_tile_xy( \$tile_x, \$tile_y, \$scale );``````

# DESCRIPTION

While working on the mapping tools on toxicrisk.com I came to the conclusion that we were dealing with too much data to make everything a GMarker, even when using the marker manager.

So, I needed to generate static map tile images. But, to do this, I needed a way to convert my decimal lat/lon points in to tile numbers, and the pixel values on those tiles.

This module makes this process simple and accurate.

# FUNCTIONS

## coord_to_gmap_tile

``    my (\$tile_x, \$tile_y) = coord_to_gmap_tile( \$lat, \$lon, \$zoom );``

Given a decimal latitude and longitude, and a Google Maps zoom level (0 being farthest away and 20 being the closest that I'm aware of that you can get), this function will return the GMap tile location as a fractional x and y coordinate.

## zoom_gmap_tile

``    my (\$new_tile_x, \$new_tile_y) = zoom_gmap_tile( \$tile_x, \$tile_y, \$old_zoom, \$new_zoom );``

Converts fractional tile coordinates, as created by coord_to_gmap_tile(), from one zoom level to another.

## gmap_tile_xy

``    my (\$x, \$y) = gmap_tile_xy( \$tile_x, \$tile_y, \$scale );``

Given a tile's x and y coordinate as provided by coord_to_gmap_tile(), this function will return the pixel location within the tile.

The `\$scale` argument may be supplied which can be used to produce high-res tiles. At this time Google states that the scale can be `1`, `2`, or `4` (only Google Maps API for Work customers can use `4` with the Google Maps API). If not specified the scale will default to `1`.

# TODO

• Implement a routine to convert tile coordinates back in to lat/lon decimal coordinates.

# AUTHOR

Aran Clary Deltac <bluefeet@gmail.com>