maemo.org - Talk - [Solved] Maemo GPS Location with Qt

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[Solved] Maemo GPS Location with Qt

Hi,

I am developing a GPS tracking application.
I have been following the location API on this page:
http://wiki.maemo.org/PyMaemo/Using_Location_API

The problem is, I couldn't run it in a simple Qt application

Code:

import location as gps

import logging



class myGPS:



    def __init__(self):

        self.control = gps.GPSDControl.get_default()

        self.device = gps.GPSDevice()

        self.control.set_properties(preferred_method=gps.METHOD_CWP,

                                    preferred_interval=gps.INTERVAL_5S)

        

        self.control.connect("error-verbose", self.onGPSError)

        self.device.connect("changed", self.onGPSData, self.control)

        self.control.connect("gpsd-stopped", self.onGPSStop)

    

    def start(self):

        logging.debug("GPS started")

        try:

            self.control.start()

        except Exception, err:

            logging.exception("start:")

    

    def stop(self):

        self.control.stop()

    

    def onGPSError(self, control, error, data):

        logging.debug("GPS Error: " + str(error))

    

    def onGPSData(self, device, data):

        if not device:

            return

        

        lat = device.fix[4]

        lng = device.fix[5]

        alt = device.fix[7]

        speed = float(device.fix[11])

        accuracy = float(device.fix[12])

        

        logging.info("Input: received")

        logging.info(lat, lng, alt, speed, accuracy)

    

    def onGPSStop(self, control):

        logging.debug("GPS Stopped")

When I trigger using start, the GPS symbol appears for a moment (blinking for 1~2s) then the application terminates.
In the log, I could only find "GPS started"

Any help is appreciated, Thank You.

Re: Maemo GPS Location with Qt

I have found the solution.
Here's the sample code for any of you who are still wondering.

Code:

import location as gps

import gobject



class myGPS():

    

    def __init__(self):

        try:

            self.boolLoop = False

            self.loop = gobject.MainLoop()

            

            self.control = gps.GPSDControl.get_default()

            self.device = gps.GPSDevice()

            self.control.set_properties(preferred_method=gps.METHOD_USER_SELECTED,

                                        preferred_interval=gps.INTERVAL_5S)

            

            self.control.connect("error-verbose", self.on_error, self.loop)

            self.device.connect("changed", self.on_changed, self.control)

            self.control.connect("gpsd-stopped", self.on_stop, self.loop)

            print "GPS object created"

        except Exception, err:

            print "Cannot Init:"

    

    def on_error(self, control, error, data):

        print ("location error: %d... quitting" % error)

        data.quit()

    

    def on_changed(self, device, data):

        if not device:

            return

        if device.fix:

            # get all the data needed from device.fix

            if device.fix[1] & gps.GPS_DEVICE_LATLONG_SET:

                print ("lat = %f, long = %f" % device.fix[4:6])

                print ("acc = %f" % device.fix[12])

    

    def on_stop(self, control, data):

        print "GPS stop"

    

    def start_location(self, data):

        data.start()

    

    def start(self):

        print "GPS start"

        if self.boolLoop:

            self.control.start()

        else:

            gobject.idle_add(self.start_location, self.control)

            self.loop.run()

            self.boolLoop = True

        

    def stop(self):

        self.control.stop()

On the other hand, I'm still not sure why I need to use gobject, without it it won't work.
To my understanding, the control.start runs the GPS thread by itself.
If someone could explain about gobject and its mainloop, it'll be appreciated.

Thanks