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opensciencemap / vtm

a vector-tile map library written in java - running on android, desktop and within the browser
GNU Lesser General Public License v3.0
238 stars 176 forks source link

Reading tile data from the stream #138

Open AAverin opened 9 years ago

AAverin commented 9 years ago

Currently MapFileTileSource requires an absolute path to the tiles file. Android Assets can't really provide an absolute path, but can give you a stream to an asset file. Is there an option to create mapsfore tile directly from the stream?

hjanetzek commented 9 years ago

It's probably not that simple as one needs to be able to seek quickly within the file. I would suggest to copy the map asset to a temporary file instead: http://stackoverflow.com/questions/9335379/randomaccessfile-in-android-raw-resource-file

AAverin commented 9 years ago

That is what I do now. But the idea is that we provide some initial world map with the application, and it's quite large. It takes ~10 seconds to copy the map to sdcard from assets and load it up. I hoped to be able to load the file as it is from the assets stream so it would speed up initial startup process.

hjanetzek commented 9 years ago

Depending on the performance of AssetInputStream.seek() it should be feasable to use the asset directly. In this case one could abstract the use of RandomAccessFile as, say, 'MapFile' and implement it also for assets. It seems the are only a handful of places in MapDatabase and ReadBuffer which need to be modified. To me the mapsforge tilesource is legacy code and I would rather look into supporting the osmand or libosmscout format for offline maps.

AAverin commented 9 years ago

As far as I know, mapsforge is the only offline maps format supported by library at the moment, right? So we kinda have to stick with it. I also don't like the performance of displaying many maps in the mapsforge format - when I browse the map it becomes slow very quickly. Are there any exact plans on supporting other formats?

andreynovikov commented 9 years ago

Any updates on support for offline maps?