On Tue, Jun 2, 2015 at 10:18 PM, Frans Schreuder
<fransschreuder@xxxxxxxxx <mailto:fransschreuder@xxxxxxxxx>> wrote:
Dear Ubuntu-phone mailing list,
I have spent a few weeks developing an offline routing / navigation
application (LGPL) based on openstreetmaps / libosmscout.
I want to publish the app in the Ubuntu App Store, but I am facing a
problem: I need read access on a location on the SD card. I will
explain
why.
1.) The maps take quite some space on the device (Netherlands is
1.3GB,
Germany is 4+ GB). At least on the BQ Aquaris this space is not
available in the home directory, at least not if you also want to
remain
with some space available.
2.) The maps have to be converted to a binary format with a tool
on the
PC. Until I got some server space and time to host some readily
converted maps, the user will have to transfer maps manually to the
phone. If this would be the app data space, that location is not by
default readable if you browse the phone on the PC.
3.) Converting the maps on the phone is not really an option, as the
process uses several GB as temp space, and on an i7 pc it can take
over
1 hour for a map of a small country.
Could you use the OBF format, and possibly reuse (for now) the
pre-generated files
from http://download.osmand.net/rawindexes/ ?
The uncompressed OBF files are a bit less than 2x the corresponding
ZIP file.
For detailed countries (so huge OBF), the OSMAND project has split
those countries in regions.
In addition, I remember a very recent discussion about privacy
concerns if the maps are shared among applications.
That is, a third-party app could check what tiles are cached, thus
figure out where the user has been.
I could not find the exact discussion and Google search in my e-mails
did not help.
I would say that this is not a huge concern for the vector maps,
because they cover a whole country.
Thus, the privacy would be for an app that was forbidden to find the
location (no access to GPS, neither the MCC/MNC SIM details).
But still, the app can easily deduce the country anyway simply from GEOIP.
I think that having a way to support shared OBF files, so apps can
reuse them, would be a big win.
If an app needs OpenStreetMap maps for a non-cached region, then the
service that deals with the OBF files
would ask the user "Hey, you are trying to view the maps for Poland,
shall we download these?".
Simos
