Hi Graham So, how do you define a "meaningful" GPS signal?
The GPS data you'll receive from locationChanged messages may have nothing for 1-n messages at the start, followed by an increasingly accurate number of messages (as measured by the "horizontal accuracy" and/or "vertical accuracy" data items). The other apps will be utilising these to determine a "meaningful" signal. You can define that however you like, of course! :-) Another thing you'll need to deal with is intermittent GPS signal which can happen for a number of reasons. Anyway, good luck. LC can do the sensor stuff well I think, I'ill look forward to seeing what you come up with! cheers Alan > On 26 Apr 2020, at 7:11 pm, Graham Samuel <livf...@mac.com> wrote: > > Alan, thanks for your two messages. II’m doing most of what you suggest (not > using accuracy so far, but the prudent person probably should do!), but > nevertheless I would like to emulate my fitness app example. I have apps that > positively know when they have acquired a meaningful GPS signal, whereas the > methods i’m using contain an element of chance or guesswork. I want to > completely eliminate that. > > In practical terms, I can’t start the sensor until the user needs it, because > of battery drain - you will find this in most trekking and fitness apps - one > is more or less confined to a button ‘Start’ or something similar. At that > point, my ideal would be to show the user that I’ve started the sensor > acquisition and tell them when it’s succeeded or failed. I feel it has to be > possible, but perhaps not with LC. > > Graham > > >> On 26 Apr 2020, at 02:47, Alan Stenhouse <alanstenho...@hotmail.com >> <mailto:alanstenho...@hotmail.com>> wrote: >> >> Hi Graham >> >> Some ideas, from experience: >> >> 1. Start your sensor on openStack or as soon as possible. >> >> 2. Ignore locationChanged messages with empty location or if "horizontal >> accuracy" is outside a threshold of x metres. >> >> 3. Just set a flag or other mechanism when you want to start and stop >> tracking which indicates to your locationChanged handler to record or stop >> recording the track. >> >> Hopefully that sounds reasonable? >> >> cheers >> >> Alan >> >>> On Sat, 25 Apr 2020 14:07:01,Graham Samuel <livf...@mac.com >>> <mailto:livf...@mac.com>> wrote: >>> >>> >>> Typical fitness apps (such as iCardio by FitDigits) can read various >>> sensors including a Heart Rate Monitor via Bluetooth, and one?s location >>> via inbuilt GPS. When you start an activity like a run or a workout, the >>> app goes through an acquisition phase, and won?t start recording until the >>> sensors are functioning. This is made clear to the user by a display. >>> >>> I want to do this in my LC iOS app, specifically for the GPS. I know how to >>> start the location function on the device and I know how to handle the >>> position via ?locationChanged' and/or ?mobileCurrentLocation', and these >>> work. The big problem is at the start of such a sequence. I can use >>> 'mobileStartTracking Sensor ?location? ? to get going, but experience shows >>> that this takes an unpredictable amount of time, sometimes of the order of >>> seconds. You would think that the locationChanged messages wouldn?t start >>> firing until the start tracking process had done its job, but it seems this >>> is not so, and nonsense locations can appear at the beginning of the >>> sequence. At least that?s my experience. >>> >>> I am loth to use a loop to see if the tracking is really started and legit, >>> and anyhow this would be problematical if my app was being inundated with >>> ?locationChanged' messages while the loop is running. >>> >>> Has anyone any experience of this issue? As usual, I feel I?m missing >>> something. Perhaps the ?trackingError? message might help, but I don?t see >>> how. >>> >>> Graham >> > _______________________________________________ use-livecode mailing list use-livecode@lists.runrev.com Please visit this url to subscribe, unsubscribe and manage your subscription preferences: http://lists.runrev.com/mailman/listinfo/use-livecode
