[Patch?] WMS-Plugin: Implement caching

[stoecker]

The WMS plugin should cache the downloaded pictures.

[stoecker]

Lakewalker already has code which does tile caching.

[RussNelson]

What should the caching policy be? keep no more than a given size? keep no more than a given count? keep no longer than a certain time?

[stoecker]

I would suggest size and time. So
if older than xxx --> delete
if more than xxx bytes --> delete oldest

I think lakewalker uses same strategy.

[xeen]

Simple Cache

[xeen]

This is a simple cache class that encapsulates image getting and saving. The grabber needs to invoke it manually by passing an (unique) identifier. It automatically discards old files but it doesn't clean up automatically.

Default values are 40 MBytes or older 5 days, whichever comes first. Can be overwritten though using wmsplugin.cache.size (in Bytes) and wmsplugin.cache.expire (in ms). I've tested it and it speeds up displaying if an image is cached (well, that was expected) but unfortunately doesn't help with the "Oberpfalz Performance" and I have no idea why.

[anonymous]

The display performance could probably be increased a lot when the current display is buffered. I think ATM every operation is done for each refresh (i.e. aligning pics, converting pics, scaling pics, ...). All of this is useless overhead when nothing changed. See #1954.

[anonymous]

Applied but not yet uploaded as plugin.