prefetched / external cacheable web map tiles

[GoogleCodeExporter]

Like Issue 18, while using OSMRenderer to download tiles on the fly, these 
tiles can be cached in external files(possibly same format as the 
MapnikRenderer's). Such cache is also reusable on next startup or while no 
connection being available (as "offline maps").
User could even manually predownload a specified area with specified zooms from 
tile server as external cache.

The difference between Issue 18 is that I propose to combine some functionality 
of MapnikRenderer into OSMRenderer rather than switch between them (cause they 
could handle incompatible datasets).

Original issue reported on code.google.com by fever...@gmail.com on 17 Dec 2010 at 7:59

[GoogleCodeExporter]

At the moment the internal network manager uses a persistent cache for the 
tiles, but it is limited to 50MB.

Would the following changes achieve what you want to accomplish?:

 - Make the cache size configurable
 - Add "clear cache" option
 - Add option to prefetch tiles along a route

Original comment by veaac.fd...@gmail.com on 17 Dec 2010 at 9:39

• Added labels: Type-Enhancement
• Removed labels: Type-Defect

[GoogleCodeExporter]

Yes, I noticed QNetworkDiskCache could do the same thing, while the current 
MapnikRenderer's format is yet not capable of doing such seamless caching. Add 
a route to prefetch tiles in specified area and zoom levels would also be 
enough for off line map case.

Original comment by fever...@gmail.com on 17 Dec 2010 at 11:41

[GoogleCodeExporter]

MapnikRenderer's format would be able to manage adding new tiles etc.. but it 
would not be feasible to delete tiles ( which is necessary unless you want to 
display outdated tiles ). Therefore I will stick to QNetworkDiskCache for the 
moment, although it puts a lot of strain on the file system, i.e., one file per 
tile.

Original comment by veaac.fd...@gmail.com on 17 Dec 2010 at 12:25

• Changed state: Accepted