# Twisted Positioning

`twisted.positioning`: geolocation in Twisted

## Introduction

`twisted.positioning` is a package for doing geospatial positioning (trying to find where you are on Earth) using Twisted.

## High-level overview

In `twisted.positioning`, you write an `IPositioningReceiver` implementation that will get called whenever some information about your position is known (such as position, altitude, heading…). The package provides a base class, `BasePositioningReceiver` you might want to use that implements all of the receiver methods as stubs.

Secondly, you will want a positioning source, which will call your `IPositioningReceiver`. Currently, `twisted.positioning` provides an NMEA implementation, which is a standard protocol spoken by many positioning devices, usually over a serial port.

## Examples

`nmealogger.py`

    #!/usr/bin/env python
    # Copyright (c) Twisted Matrix Laboratories.
    # See LICENSE for details.
    """
    Connects to an NMEA device, logs beacon information and position.
    """

    import sys

    from twisted.internet import reactor, serialport
    from twisted.positioning import base, nmea
    from twisted.python import log, usage

    class PositioningReceiver(base.BasePositioningReceiver):
        def positionReceived(self, latitude, longitude):
            log.msg(f"I'm at {latitude} lat, {longitude} lon")

        def beaconInformationReceived(self, beaconInformation):
            template = "{0.seen} beacons seen, {0.used} beacons used"
            log.msg(template.format(beaconInformation))

    class Options(usage.Options):
        optParameters = [
            ["baud-rate", "b", 4800, "Baud rate (default: 4800)"],
            ["serial-port", "p", "/dev/ttyS0", "Serial Port device"],
        ]

    def run():
        log.startLogging(sys.stdout)

        opts = Options()
        try:
            opts.parseOptions()
        except usage.UsageError as message:
            print(f"{sys.argv[0]}: {message}")
            return

        positioningReceiver = PositioningReceiver()
        nmeaReceiver = nmea.NMEAAdapter(positioningReceiver)
        proto = nmea.NMEAProtocol(nmeaReceiver)

        port, baudrate = opts["serial-port"], opts["baud-rate"]
        serialport.SerialPort(proto, port, reactor, baudrate=baudrate)

        reactor.run()

    if __name__ == "__main__":
        run()

- Connects to an NMEA device on a serial port, and reports whenever it receives a position.