[Tilesathome] lowzoom in tilesGen.pl

[Dirk Stöcker]

Hello,

I tried to make some lowzoom stuff, but had too many problems with the 
lowzoom_composite.pl, so I rewrote the stuff inside of Tileset.pm.

What changed:
- Tileset.pm now can generate lowzoom tiles also for captionless and tile
   (also maplint, but this is probably not very helpful :-).
- The code is encapsulated, so that no additional requirements are visible
   for the generic client.
- required: Image::Magick, LWP::Simple, File::Compare
   when not installed, an error is printed in case the lowzoom tiles except
   caption are tried. I did not want to introduce a generic ImageMagick
   requirement.
- The empty tile detection and handling should now work as expected.
- Support for oceantiles.dat to check whether tile status matches
   oceantiles or to have more up-to-date oceantiles than server has.
   The local file is used in case of conflicts (and a message is printed).

Use it like this:
./tilesGen.pl xy num num 6 caption,captionless,tile
(The default to render only caption is unchanged!)

The support is very strict. Missing tiles abort entire operation. Maybe 
the integration into automatic calls is not perfect now, but as the server 
does not handle that anyway ATM I leave that to future improvements.

I tested the stuff with 6,39,23 and nearly everything looks fine.


Tile 10,631,378 has wrong color, which probably comes from the ImageMagick 
bug workaround with the transparent captions.

I already reported that bug to ImageMagick and it is fixed in next 
release, but that does not help now. Problem: Transparency for caption 
files is ignored in ImageMagick >= 6.4.3 for some type of PNG's. My 
current workaround is to resave the file using GD.
Better suggestion wellcome.

Ciao
-- 
http://www.dstoecker.eu/ (PGP key available)