[wip] add showUserHeading option to GeolocateControl

[andrewharvey]

Launch Checklist

• briefly describe the changes in this PR

Add a showUserHeading option to the GeolocateControl to show the device heading as an arrow next to the user location dot.

Sensor access is disabled by default in Safari from iOS 12.2+, so for this to work you need to enable that setting in Safari Settings, once enabled it uses deviceOrientationEvent.webkitCompassHeading.

closes #8329
closes #8034

• include before/after visuals or gifs if this PR includes visual changes

• write tests for all new functionality
• document any changes to public APIs
• post benchmark scores
• manually test the debug page
• tagged @mapbox/studio and/or @mapbox/maps-design if this PR includes style spec or visual changes
• tagged @mapbox/gl-native if this PR includes shader changes or needs a native port
• cross device testing
• investigate if it's better to use https://developer.mozilla.org/en-US/docs/Web/API/Coordinates/heading instead of deviceorientation.

[ahk]

Thanks for this PR. I'm curious if you have knowledge/experience/thoughts about how many users choose to enable sensor access in mobile Safari. Is this different from the permissions dialog that asks if location data should be enabled on a per-site basis?

[andrewharvey]

Thanks for this PR. I'm curious if you have knowledge/experience/thoughts about how many users choose to enable sensor access in mobile Safari. Is this different from the permissions dialog that asks if location data should be enabled on a per-site basis?

No idea how many enable it, but probably very little have it enabled since it's off by default and most users would have no reason to enable it, that said an application could prompt you to go into settings and enable, and I think applications can still do that independently if they like. So I still think we should support it when it is enabled.

It's an all or nothing switch in Safari (in the app settings) it's different to the permissions dialog for location access.

I investigated the coords.heading field from the geolocation API https://developer.mozilla.org/en-US/docs/Web/API/Coordinates/heading and found that iOS Safari doesn't support it (tested on iOS 12.4.2). Chrome on Android does, but that already supports an absolute bearing from deviceorientation.

[ahk]

I investigated the coords.heading field from the geolocation API

Do you think we should also support this field as well? I have Firefox and Firefox Preview on my Android phone. As well it's possible for desktop/laptop Firefox to have a compass reading in some weird cases right?

[ahankeosi]

Any movement on this? Would really love this feature!

[andrewharvey]

Any movement on this? Would really love this feature!

Nope, feel free to pick up my work in progress if you feel it's helpful.

[CptHolzschnauz]

Stick to one's guns ! Any movement to PR?

[andrewharvey]

this was completed by @tsuz in #10817