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# gpx(n) 1.1 tcllib "GPS eXchange Format (GPX)"

## Name

gpx - Extracts waypoints, tracks and routes from GPX files

## Synopsis

- package require Tcl 8.5 9
- package require gpx ?1.1?

- ::gpx::Create gpxFilename ?rawXML?
- ::gpx::Cleanup token
- ::gpx::GetGPXMetadata token
- ::gpx::GetWaypointCount token
- ::gpx::GetAllWaypoints token
- ::gpx::GetTrackCount token
- ::gpx::GetTrackMetadata token whichTrack
- ::gpx::GetTrackPoints token whichTrack
- ::gpx::GetRouteCount token
- ::gpx::GetRouteMetadata token whichRoute
- ::gpx::GetRoutePoints token whichRoute

## Description

This module parses and extracts waypoints, tracks, routes and metadata from a GPX (GPS eXchange) file. Both GPX version 1.0 and 1.1 are supported.

## COMMANDS

::gpx::Create gpxFilename ?rawXML?

  The ::gpx::Create is the first command called to process GPX data. It takes the GPX data from either the rawXML parameter if present or from the contents of gpxFilename, and parses it using tdom. It returns a token value that is used by all the other commands.

::gpx::Cleanup token

  This procedure cleans up resources associated with token. It is strongly recommended that you call this function after you are done with a given GPX file. Not doing so will result in memory not being freed, and if your app calls ::gpx::Create enough times, the memory leak could cause a performance hit...or worse.

::gpx::GetGPXMetadata token

  This procedure returns a dictionary of the metadata associated with the GPX data identified by token. The format of the metadata dictionary is described below, but keys version and creator will always be present.

::gpx::GetWaypointCount token

  This procedure returns the number of waypoints defined in the GPX data identified by token.

::gpx::GetAllWaypoints token

  This procedure returns the a list of waypoints defined in the GPX data identified by token. The format of each waypoint item is described below.

::gpx::GetTrackCount token

  This procedure returns the number of tracks defined in the GPX data identified by token.

::gpx::GetTrackMetadata token whichTrack

  This procedure returns a dictionary of the metadata associated track number whichTrack (1 based) in the GPX data identified by token. The format of the metadata dictionary is described below.

::gpx::GetTrackPoints token whichTrack

  The procedure returns a list of track points comprising track number whichTrack (1 based) in the GPX data identified by token. The format of the metadata dictionary is described below.

::gpx::GetRouteCount token

  This procedure returns the number of routes defined in the GPX data identified by token.

::gpx::GetRouteMetadata token whichRoute

  This procedure returns a dictionary of the metadata associated route number whichRoute (1 based) in the GPX data identified by token. The format of the metadata dictionary is described below.

::gpx::GetRoutePoints token whichRoute

  The procedure returns a list of route points comprising route number whichRoute (1 based) in the GPX data identified by token. The format of the metadata dictionary is described below.

## DATA STRUCTURES

metadata dictionary

  The metadata associated with either the GPX document, a track, a route, a waypoint, a track point or route point is returned in a dictionary. The keys of that dictionary will be whatever optional GPX elements are present. The value for each key depends on the GPX schema for that element. For example, the value for a version key will be a string, while for a link key will be a sub-dictionary with keys href and optionally text and type.

point item

  Each item in a track or route list of points consists of a list of three elements: latitude, longitude and metadata dictionary. Latitude and longitude are decimal numbers. The metadata dictionary format is described above. For points in a track, typically there will always be ele (elevation) and time metadata keys.

## EXAMPLE

    % set token [::gpx::Create myGpxFile.gpx]
    % set version [dict get [::gpx::GetGPXMetadata $token] version]
    % set trackCnt [::gpx::GetTrackCount $token]
    % set firstPoint [lindex [::gpx::GetTrackPoints $token 1] 0]
    % lassign $firstPoint lat lon ptMetadata
    % puts "first point in the first track is at $lat, $lon"
    % if {[dict exists $ptMetadata ele]} {
         puts "at elevation [dict get $ptMetadata ele] meters"
      }
    % ::gpx::Cleanup $token

## REFERENCES

1. GPX: the GPS Exchange Format (http://www.topografix.com/gpx.asp)

2. GPX 1.1 Schema Documentation (http://www.topografix.com/GPX/1/1/)

3. GPX 1.0 Developer's Manual (http://www.topografix.com/gpx_manual.asp)

## AUTHOR

Keith Vetter

## Bugs, Ideas, Feedback

This document, and the package it describes, will undoubtedly contain bugs and other problems. Please report such in the category gpx of the Tcllib Trackers. Please also report any ideas for enhancements you may have for either package and/or documentation.

When proposing code changes, please provide unified diffs, i.e the output of diff -u.

Note further that attachments are strongly preferred over inlined patches. Attachments can be made by going to the Edit form of the ticket immediately after its creation, and then using the left-most button in the secondary navigation bar.

## Keywords

gps, gpx

## Category

File formats

## Copyright

Copyright © 2010, Keith Vetter <kvetter@gmail.com>