[Openstreetmap-dev] Workings of maps.civicactions.net

[Nick Whitelegg]

Tom, (or anyone else...)

Been looking quickly at the maps.civicactions.net source code but am a bit
puzzled as to how it's working, and in particular, how the server sends
back new map tiles as you pan round the world.

All the server seems to send back to the client when you pan round, as a
response to the XmlHttpRequest, is a stream of data describing latitude,
longitude etc.  This then seems to be to draw a different section of tile
on the div. Nowhere does the server actually appear to send back *new* PNG
tiles when you pan away from the current area.

Am I correct therefore that *all* tiles are downloaded to the client when
the application starts i.e. there's no continual retrieval of PNG images
from the server as the user pans round the world? My interpretation of the
source would suggest so. For a higher resolution map such as OpenStreetMap
or Freemap I can't see how that would be feasible.


Thanks,
Nick