getlla

A cross-platform location source abstraction that polls available GPS APIs or hardware for a position

WIP!

This README is closer to a braindump. There are no docs yet. This crate is a proof-of-concept stage.

The codebase is going to start out as a collection of minimal POCs across platforms before they are woven together into a usable API

Goals

• Cover the platforms listed below
  • MacOS
    • Should we make the calls to main loop optional?
  • Linux
  • Windows
  • Android
  • iOS
• To the extent possible, support cross-compiling
  • Windows to MacOS is unlikely due to XCode licensing.
  • MacOS should be able to cross compile to everybody else
• Avoid spawning subprocesses
• Provide a generic error type
• To the extent possible, handle permission requests
  • What is a reasonable abstraction for triggering such permission requests?
• Platform-specific logging with approrpiate log creates
• Probably do futures, since the underlying implementations tend to be async/callback-oriented

Caveats & Permissions

MacOS

MacOS requires code-signing and an "app" directory structure, with an "Info.plist" that declares the reasoning for the location sevices permission. Without this file, even explictly requesting the permission will not If you can find a good workaround for this (that communicates the same info.plist information through other framework APIs), contributions ar

A script to do this is currently in build.sh

Android

TODO. There will be likely be some android permissions and manifest.xml entries

Windows

No additional permissions are necessary, unless you are making a windows store app. In which case you must define ID_CAP_LOCATION in the application manifest. Settings > Location

If the user disables Location permissions, calling get_permissions will open the settings app on the location privacy page to encourage them to update their selection.

Linux

Unsure of the canonical way for accessing built-in GPS recievers for laptops running linux - this may be highly vendor specific, or it may be as simple as opening a serial device. Will investigate. libgps/gpsd seem to cover some of these bases

iOS

TODO: Haven't tried this on iOS. Probably similar to MacOS CoreLocation with some extra steps

External GPS Devices (serial)

TODO. Add support for generic NMEA serial devices, and maybe the ublox binary protocol.

External GPS Devices (userspace serial)

IIRC there is an existing open-source effort to implement userspace USB serial drivers using nusb/rusb. These drivers would enable external serial GPS recievers on Android.

Support tiers

MacOS, Android, Windows, Linux, NMEA serial should be tier 0 external serial devices other than NMEA (like ublox's own protocol) tier 1 iOS tier 2 Android with an external userspace serial device tier 3 (for Android, we can enable JVM-land implemenations of userspace serial to pass us raw serial via FFI, which we then parse. messy imo)