Yeah, that's what I've been thinking as well - hide all the elements you put on top when user starts interacting with the map itself (drag, pinch, rotation) or if the map widget animates (switching to a new center, induced zoom/rotation/pitch change).
Still might not be always doable, for example if centering is enabled & centering is animated. That way there would basically be no time as which to show the custom widgets as the Open GL widget would be animating & asynchronously changing to arbitrary coordinates all the time.

There could still be workaround but I'll likely just try to use the polyline/polygon/marker API where possible.


That's a good point - it should be fine to just handle the GeoJSON internally as long as there is an API that can be used to add/remove objects from the map.

A rough outline what would enable modRana support it's current map overlay feature set:

* position indicator API
- show current position & the direction of travel
- turn position display on/off

This is how the modRana position indicator looks like:



* POI marker API
usecase: show POI on the map
- add/remove markers given as a lat/lon coordinate with a label
- each marker should likely have an unique id (app provided/returned by function call ?)
- would it be possible to make the marker label clickable ? (eq. a markerClicked signal returning the id of the marker if callback registration would be too complicated)
- in general the markers & labels should be drawn on top of any polylines or polygons if possible

BTW, this is how modRana created POI markers look at the moment:



* polyline API
usecases: show tracklogs, navigation routes, live logging trace
- add/remove polylines given as ordered lists of lat/lon coordinates
- again they should have unique IDs
- for drawing routes it would he handy to be able to supply also a second list of points that would be highlighted on top of the polyline (turn points)
- alternatively this could be emulated by drawing POIs without labels for the turn points, requiring a bit extra map object management code on the application side
- for the specific use case of drawing on map trace/live logging trace (eq. basically a live trail of last visited points) an appendable polyline would be nice, if possible, as removing/adding a new polyline every location update would likely not work very well
- or there could be a special built-in "trail" polyline that would automatically track current location and could be turned on/off - that way it should be possible to avoid the trail lagging behind the position indicator

ModRana currently draws routes like this:

The yellow points are turn points and the red/green circles are start/destination designators. Tracklogs & logging traces look similar, but don't have the turn points and start/destination designators.


* polygon API
use cases: show areas of interest, map area selection
- add/remove polygons given as ordered lists of lat/lon coordinates
- again they should have unique IDs
- color selection would likely by handy to tell polygons apart
- labels are likely not needed - one can just place a labeled marker inside the polygon

ModRana currently does not draw polygons on the map.

This is just a rough outline and feedback from other potential users of the widget is certainly welcome!


Definitely! I guess it would be different if there were some widely available aerial/satellite map layers as that's something one can't really render from map data. But that's unfortunately not the case (unless some of the emerging small-sat constellations help with that) and we should be basically able to draw anything else.