improve geolocation's shouldStopTrackingLocation

[wbazant]

I thought I just broke this, but the beta site also has the issue - you can zoom out quite far, and still have the dot:

• switch off geolocation when map is zoomed out past a threshold
• switch off geolocation when it is on, and the crosshair symbol is on

when coming back to the place textbox after it had input, re-open suggestions. I searched Birmingham, zoomed in, and wanted to come back to the view of the city. Clicking on the text box doesn't do anything:
and I get suggestions back only after I type a space. (moved to #426)

[ezwelty]

switch off geolocation when it is on, and the crosshair symbol is on

@wbazant By "crosshair symbol is on", do you mean when the user uses the place search box to select a place to navigate to? I would tie the logic rather to this action, because we may or may not always wish to display a crosshair (see my comment regarding approximate places #419 (comment)). Anyway, I think it makes sense to stop tracking location in this case.

switch off geolocation when map is zoomed out past a threshold

I don't see this as necessarily always a good thing (could be useful sometime to see one's location in context?), but if we went this way, we could use the max cluster zoom level as the threshold.

[wbazant]

I meant the place selection, rather than the place crosshair being on the map, you're right!

Now that I come back to this issue, I think the original heuristics for stopping geolocation, or my proposed ones, don't make sense. There's no reason why selecting a place or zooming out should switch geolocation off. Maybe a better resolution would be to base the behaviour on whether the geolocation dot is inside the map bounds after the view change. If we zoom into a region without the geolocation, or select a place outside the map, tracking should be switched off (there's no more need to track the dot's whereabouts after the user did something that loses it) but zooming out never loses the dot, and searching may or may not lose it.

[wbazant]

Closed in favour of #518