TileLayer: Simplify the max_zoom logic

I’m hoping/thinking this might just be a user issue on my end, but it is currently appearing that TileLayer’s max_zoom value is capped at 18 even after setting it to a higher value. For example, in this MyBinder demo’s example.ipynb: https://mybinder.org/v2/gh/banesullivan/localtileserver-demo/HEAD which I have modified below:

from localtileserver import examples, get_leaflet_tile_layer, TileClient
from ipyleaflet import Map

# Create a tile server from an raster URL
oam = TileClient('https://oin-hotosm.s3.amazonaws.com/59c66c5223c8440011d7b1e4/0/7ad397c0-bba2-4f98-a08a-931ec3a6e943.tif')

# Create ipyleaflet TileLayer from that server
# Please note that all extra kwargs are passed to `TileLayer`
oam_layer = get_leaflet_tile_layer(oam, max_zoom=24, show_loading=True)

# Create ipyleaflet map, add layers, add controls, and display
m = Map(center=oam.center(), zoom=20, max_zoom=100)
m.add_layer(oam_layer)
m

>>> from ipyleaflet import TileLayer
>>> isinstance(oam_layer, TileLayer)
True
>>> oam_layer.max_zoom
24

No matter how much I zoom in, I can watch the network tab in the browser and see that the tile requests coming from that TileLayer never exceed zoom level 18, e.g., .../proxy/41129/api/tiles/18/85161/117721.png

I know that this image source has a max zoom level of 24 and localtileserver will continue serving tiles at whatever zoom level is requested regardless of the cap in the data source.

So I’m wondering what is missing here to make sure TileLayer can continue to fetch tiles beyond zoom level 18.

Additional context

ipyleaflet	CesiumJS
in the share mybinder	https://tileserver.banesullivan.com/?filename=https%3A%2F%2Foin-hotosm.s3.amazonaws.com%2F59c66c5223c8440011d7b1e4%2F0%2F7ad397c0-bba2-4f98-a08a-931ec3a6e943.tif

This is very high resolution imagery and it’d be fantastic to visualize at full resolution with ipyleaflet

[martinRenou]

@banesullivan you should not need to provide a max_zoom for the Map anymore, its value is None by default (like in LeafletJS) which means the map takes the max value of the tile layers max zoom automatically.

[martinRenou]

@XingongLi @giswqs As @davidbrochart was saying, I understand you need to set the max_native_zoom property as well.

For example, - I think max_zoom of TileLayer should be set to None such that the tiles are never turned off by default when zooming passed them, instead the images should be scaled - the max_zoom of the TileLayer could, by default, match the max_native_zoom. This would prevent the tiles from disappearing before reaching the maximum zoom. - the Map’s max_zoom could be reset to the TileLayer in the Map with the highest zoom level if above 18. - If setting zoom on Map to something greater than the default max_zoom of 18, max_zoom should be increased

@banesullivan I agree we should simplify this and this sounds like a sensible approach. We could also probably remove the Map’s max_zoom property from the Python API and handle it ourselves in ipyleaflet’s JavaScript code.