How to load osmdroid tiles at the end of the user?

Question

I already managed to download map fragments from the osmdroid SD card (Mapnik)

But now I want to indicate in the Android application to download the map that the user wants to use; the middle map shows online; the user selects a specific area and uses it to use it; I don’t know how to do this, please help, thanks

Answer 1

I am not sure what this question points to. As far as I understand, the user selects an area that is expressed in geographical coordinates, and then uses these coordinates to calculate the fragments found.

The Slippy map tilenames in the OSM quiz has a very good explanation on how to do this:

• Redesign the coordinates of the Mercator projection (from EPSG: 4326 to EPSG: 3857):

  x = lon
  y = arsinh(tan(lat)) = log[tan(lat) + sec(lat)]
  

  (lat and lon are in radians)

• Conversion range xand yto 0- 1and slide beginning in the upper left corner:

  x = [1 + (x / π)] / 2
  y = [1 − (y / π)] / 2
  

• Calculate the number of fragments on the map n, using2^zoom
• Multiply xand yon n. A round of results down to give tilexand tiley.