Make query methods return raster features/sources

[samanpwbb]

It would be useful if raster layers were included in featuresAt. Especially for raster layers with sources with limited bounds.

I see here that this is a noop:

mapbox-gl-js/js/source/raster_tile_source.js

Line 98 in 2a2aec4

callback(null, []);

[scothis]

Looks to already be working.

[samanpwbb]

@scothis in that example, the raster layers are hacked in to show up across the whole map. Ideally the raster layer only appears in the popup if it exists where user clicked.

[lbud]

At this time we don't return raster sources or features from map.query*Features at all. We should do this.

This will be dependent on #3186: querying searches for features in a tile, but since we shoehorn features into a tile, querying a point on a visible raster layer may search for points past a tile (the source cache's tile)'s "extent."

The equivalent of the noop mentioned in #1404 (comment) is now query_features.js#L12: raster layers don't have feature indices. querySourceFeatures also only queries geojson and vector data.

This was brought up in #3745. Indeed for something like a canvas-based raster layer it would be helpful to return an [x,y] coordinate mapped back to the original raster data.

[mollymerp]

This could be particularly useful for raster layers like the terrain rgb where users could query the pixel values and calculate elevation at a point based on the raster data 💭