Initial plugin design

[simonw]

This plugin will work by scanning all other attached databases to see if they are a valid MBTiles package. It will then make those tiles available at /-/tiles/db-name/z/x/y.png

[simonw]

It's going to have an interface at /-/tiles which shows the list of available tile databases, and /-/tiles/db-name will present a Leaflet map previewing those tiles. It will depend on datasette-leaflet for that.

[simonw]

It will consult the _internal database https://docs.datasette.io/en/stable/internals.html#the-internal-database to determine if a database is a valid MBTiles package, by looking for the following tables (or views):

CREATE TABLE tiles (zoom_level integer, tile_column integer, tile_row integer, tile_data blob);
CREATE TABLE metadata (name text, value text);

See https://github.com/mapbox/mbtiles-spec/blob/master/1.3/spec.md

[simonw]

For simplicity I'll just look for the tiles database table:

select
  columns.database_name,
  columns.table_name,
  group_concat(columns.name) as columns
from
  columns
where
  columns.table_name = "tiles"
group by
  columns.database_name,
  columns.table_name
order by
  columns.table_name

Outputs:

database_name	table_name	columns
San_Francisco	tiles	tile_column,tile_data,tile_row,zoom_level
basemap	tiles	tile_column,tile_data,tile_row,zoom_level