maemo.org - Talk - location via DBUS ?

Gypsy does not support the N900 internal GPS so its not an option.

Figured out howto access location-daemon's Gypsy interface thanks
to dbus-monitor. Main things to know are:

Dbus service name: com.nokia.Location
Dbus path: /com/nokia/location/las
GPS device name: las

the rest is standard Gypsy API. Modified the gypsy python example to work with location-daemon, just enter las as the first arguement. Still some unknown issue with the position fields bitmask but appears to be working.

Code:

#! /usr/bin/python



# This example code is in the public domain.



import sys

import gobject

import dbus, dbus.service, dbus.mainloop.glib



# Some constants we need

GYPSY_DBUS_SERVICE = "com.nokia.Location"

GYPSY_DBUS_PATH= "/com/nokia/location/las"



GYPSY_CONTROL_DBUS_INTERFACE = "org.freedesktop.Gypsy.Server"

GYPSY_DEVICE_DBUS_INTERFACE = "org.freedesktop.Gypsy.Device"

GYPSY_POSITION_DBUS_INTERFACE = "org.freedesktop.Gypsy.Position"



GYPSY_POSITION_FIELDS_NONE = 0

GYPSY_POSITION_FIELDS_LATITUDE = 1 << 0

GYPSY_POSITION_FIELDS_LONGITUDE = 1 << 1

GYPSY_POSITION_FIELDS_ALTITUDE = 1 << 2



# Check that the Bluetooth ID of the GPS is specified on the command line

if len(sys.argv) != 2:

    print "$ simple-gps-python.py [bluetooh ID]"

    sys.exit(1)



# Hook into the glib main loop

dbus.mainloop.glib.DBusGMainLoop(set_as_default=True)



# Connect to the system bus

bus = dbus.SystemBus()



# Get a connection to the Gypsy control server

control = bus.get_object(GYPSY_DBUS_SERVICE, GYPSY_DBUS_PATH)



# Create a client for the specified GPS device

device=sys.argv[1]

print "Device",device

path = control.Create(device, dbus_interface=GYPSY_CONTROL_DBUS_INTERFACE)



# Get a proxy to the client

gps = bus.get_object(GYPSY_DBUS_SERVICE, path)



# Get a proxy to the Position interface, and listen for position changed signals

position = dbus.Interface(gps, dbus_interface=GYPSY_POSITION_DBUS_INTERFACE)

def position_changed(fields_set, timestamp, latitude, longitude, altitude):

    print "Fields:%u" % fields_set,

    print "%d: %2f, %2f (%1fm)" % (

        timestamp,

        (fields_set & GYPSY_POSITION_FIELDS_LATITUDE) and latitude or -1.0,

        (fields_set & GYPSY_POSITION_FIELDS_LONGITUDE) and longitude or -1.0,

        (fields_set & GYPSY_POSITION_FIELDS_ALTITUDE) and altitude or -1.0)

position.connect_to_signal("PositionChanged", position_changed)



# Get a proxy to the Device interface, and start it up

device = dbus.Interface(gps, dbus_interface=GYPSY_DEVICE_DBUS_INTERFACE)

device.Start()



# Enter the main loop, and let the signals arrive

gobject.MainLoop().run()