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Help understanding maps and themes

krussell
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Help understanding maps and themes

Thu Jul 09, 2015 1:55 am
I've built and successfully used the MarbleWidget in a test application (Marble C++ Tutorial Part 1). However, if I used Plain, Political, or sometimes OpenStreetMap themes they show as empty (as if no tiles are being loaded). I am hoping someone could help my understanding of the Marble themes/maps. My application will have to be run in an offline manner so I'm trying to understand how and where the theme data lives. Is it relative to the application .exe file, is it stored somewhere like AppData, or is it all pulled from online. Eventually I'd like to provide a central (offline) location that my application can talk to to get map data (tiles, etc) but until I'm ready for that I am looking for help/information on how marble loads it's data.

For example, the line:
Code: Select all
mapWidget->setMapThemeId("earth/openstreetmap/openstreetmap.dgml");

is a little ambiguous to me. Is the "earth/openstreetmap/openstreetmap.dgml" a relative path? Is it in reference to a location defined elsewhere (EnvVar, registry, etc.)? Or is it just an identifier that means something else? Understanding this and how/where to store the appropriate data will help me in the long run but also might help me understand why certain themes do not load in an application as simple as what is found in the 1st Marble C++ tutorial.

I feel as though I'm missing something simple since there doesn't seem to be any questions information regarding this, so many thanks to anyone who can help my understanding of this!
User avatar Earthwings
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It is a relative path and two locations are searched to resolve it: The user path first and, if no such file exists, the system path. Both paths are configurable at compile time, run time and/or with environment variables. What configuration is possible depends e.g. on the operating system. For details see section 3 in https://projects.kde.org/projects/kde/k ... ry/INSTALL and viewtopic.php?f=217&t=109840#p316617 and ultimately MarbleDirs.cpp.

 
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