A gem for working with several Ozi Explorer file formats
Ruby Gnuplot
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Rubygems API Documentation


Rozi is a Ruby gem for working with all Ozi Explorer file formats. Currently the implemented functionality is:

  • Creating and writing waypoints to files (.wpt)
  • Reading waypoints from files
  • Creating and writing tracks to files (.plt)
  • Creating Name Search Text files (.nst)


Text based file formats read by Ozi Explorer should be encoded as ISO-8859-1 and use CRLF line endings (\r\n). Rozi will handle this for you, as long as you use the methods that accept file paths. Rozi internally uses the Rozi.open_file function, which creates and returns (or yields) a File instance with the correct encoding settings for both reading and writing Ozi Explorer file formats.


Rozi.open_file("file_path.wpt", "w") { |file|
  file.write("Østre aker\n")   # Writes "Østre aker\r\n" in ISO-8859-1

Rozi.open_file("file_path.wpt", "r") { |file|
  file.read   # Reads "Østre aker\n" as UTF-8


Rozi performs input validation on datums. If you try to set the datum property of an object to a datum that isn't supported by Ozi Explorer, Rozi will raise an exception. The constant Rozi::DATUMS contains all datums that Ozi Explorer supports.


Any time you set colors in Rozi, you can either use the three-byte integer representation that Ozi Explorer expects, or you can use a hex string like "RRGGBB" and Rozi will convert it for you. Example:

# Identical
Rozi::Waypoint.new(bg_color: "ABCDEF")
Rozi::Waypoint.new(bg_color: 0xEFCDAB)
Rozi::Waypoint.new(bg_color: 15715755)

Creating waypoint files

Rozi defines a WaypointFile class, which mimics the standard library File class. The waypoint file class has two important methods:

The waypoint file "properties" are the file-wide data contained in the top 4 lines of the file. In the case of waypoint files, that's just the waypoint file version and the geodetic datum.

To write file properties, the file must be empty. Here's an example:

properties = Rozi::WaypointFileProperties.new(version: "1.1", datum: "WGS 84")

wpt = Rozi::WaypointFile.open("/path/to/file.wpt", "w")

The properties displayed here happens to be the defaults for Rozi, so you can skip this step if they work for you. When writing the first waypoint, the default properties will be added first.

Here's how you write waypoints:

wpt = Rozi::WaypointFile.open("/path/to/file.wpt", "w")

wpt.write_waypoint Rozi::Waypoint.new(
  name: "Foo", latitude: 12.34, longitude: 56.78
wpt.write_waypoint Rozi::Waypoint.new(
  name: "Bar", latitude: 12.34, longitude: 56.78


Alternatively, you can use a block for WaypointFile.open, just like with File.open:

Rozi::WaypointFile.open("/path/to/file.wpt", "w") { |wpt|
  # ...

Rozi also provides the function Rozi.write_waypoints for opening a file, writing properties, writing waypoints and closing the file in one step. Example:

waypoints = [
  Rozi::Waypoint.new(name: "Foo", latitude: 12.34, longitude: 56.78),
  Rozi::Waypoint.new(name: "Bar", latitude: 12.34, longitude: 56.78)

Rozi.write_waypoints(waypoints, "/path/to/file.wpt", datum: "WGS 84")

WGS 84 is the default datum, so specifying it is unnecessary, but it illustrates how waypoint file properties can be set using keyword arguments.


Reading waypoint files

Reading waypoints from waypoint files is even easier than writing them:

wpt = Rozi::WaypointFile.open("/path/to/file.wpt", "r")

properties = wpt.read_properties

# The most basic reading method
first_waypoint = wpt.read_waypoint
second_waypoint = wpt.read_waypoint

# Iterating over all the waypoints in the file
wpt.each_waypoint { |waypoint|
  puts "#{waypoint.name} - #{waypoint.latitude},#{waypoint.longitude}"

# Reading all waypoints into an array
waypoints = wpt.each_waypoint.to_a


Creating track files

Creating track files is very similar to creating waypoint files. Instead of the WaypointFile class, you use the TrackFile class. Instead of writing Waypoint objects, you write TrackPoint objects. Instead of using WaypointFileProperties, you use TrackProperties.

One thing to note about track files is that the file-wide properties contain a lot more information. They contain the track color, track width, track description and much more. See Rozi::TrackProperties for more information.

Rozi also has a Rozi.write_waypoints equivalent for writing tracks:

track_points = [
  Rozi::TrackPoint(latitude: 12.34, longitude: 56.78),
  Rozi::TrackPoint(latitude: 23.45, longitude: 67.89)

Rozi.write_track(track_points, "/path/to/file.plt", color: "FF0000")


Creating name search text files

See Ozi Explorer: Name Search for information about Name Search. An NST file has to be converted into a Name Database using the "Name Search Creator" tool before they can be used by Ozi Explorer.

Rozi aims to be consistent and intuitive, so creating NST files is pretty much the exact same process as creating waypoint files and track files:

properties = Rozi::NameSearchProperties.new(
  datum: "WGS 84", comment: "Generated by Rozi!"

nst = Rozi::NameSearchTextFile.open("/path/to/file.nst", "w")

nst.write_name Rozi::Name.new(name: "Foo", latitude: 12.34, longitude: 56.78)
nst.write_name Rozi::Name.new(name: "Bar", latitude: 23.45, longitude: 67.89)


Or using the module function:

names = [
  Rozi::Name.new(name: "Foo", latitude: 12.34, longitude: 56.78),
  Rozi::Name.new(name: "Bar", latitude: 23.45, longitude: 67.89)

  names, "/path/to/file.nst", datum: "WGS 84", comment: "Generated by Rozi!"