The server tells the client the hash of each tile it sends (calculated
from the contents of the tile, not its PNG encoding). When the client
asks for a tile to be refreshed, it tells the server what the hash of
the existing tile is. If the server notices that the tile contents
hasn't actually changed, it doesn't PNG encode it and doesn't send it
to the client.
The intent is that this will reduce load on the server and also avoid
unnecessary tile traffic.
Change-Id: Ia06ca68655ea984ed4319f24f4470afda322eccf
Previously tilecombine had its own version, which is
nonesensical, since it's not really a tile.
Now it passes the version to the tiles when
parsing and serializes version per-tile.
Change-Id: I5db8d94880431e3d2a40b6787c6fe51a05771305
Reviewed-on: https://gerrit.libreoffice.org/32633
Reviewed-by: Ashod Nakashian <ashnakash@gmail.com>
Tested-by: Ashod Nakashian <ashnakash@gmail.com>
