[pmapper-users] Tile caching support in p.mapper 5

[Armin B. <arm...@gm...>]

Dear all

In case of interest, I added a simple solution for on-disk tile caching 
for tiled layers in pm5. It only requires enough disk space for the 
cache image tiles and a few config parameters.

It's mainly useful for large datasets that shall be displayed at lower 
zoom levels but have too many details to be rendered acceptably fast at 
lower zoom levels. Could be vector layers with a lot of details or 
raster layers with lots of single files to be read.

The advantage to a fully-fledged tile cache solution (like MapCache) is 
that it does not require additional service set-ups. And in case of 
vector layers it also supports legend icons (and printing, once it is 
fully working...).

If you want to try, see changesets 1372 and 1375 for the files to be 
updated from svn trunk. Config parameters are listed here:
http://svn.pmapper.net/trac/wiki/XmlFileSettingsFive?action=diff&version=12

could look like
<category name="cat_admin" imgFormat="png32" olTheme="admin" buffer="0" 
themeType="PMTile" tileCache="true" cacheMaxLevel="12">

and needs under <map> an entry like
   <tileCacheRoot>/path/to/pmapper_tilecache/default</tileCacheRoot>


A corresponding basic seeding functionality is currently in test. 
Out-dated tile files, e.g. due to changes in symbology, need to removed 
manually in the directory of the tile cache. But the Unix "find" command 
allows a quite comprehensive functionality for this.

Regards
/A