[Tilecache] PILcopy layer

[Marco Nijdam]

As quoted from Richard Duivenvoorde <rdmailings at duif.net>:
> Only question I have:
> - it would be nice to make this work on layers which are not fully
> seeded too. So upon a negative test if the 'parent'-layer-tile is
> available, the Layer should 'switch back' as parent-layer first,
> generate the parent tiles. and then 'switch forward' to the copy-layer
> again to do the b&w trick. In this way we can generate two 'dependent'
> caches in one go.
> I did not manage to do that in a Layer-impl: the MetaLayer constructor
> is constructed with **kwargs, and I do not no how to store those for use
> in 'renderTile'.
> 
> Somebody an idea for that?

Why not make it "just another layer" in tilecache, with the "parent"
layer configured as WMS(C) server source. So Tilecache would call itself
for the parent layer image via WMS(C) URLs.

Then the only new feature in the child layer would be a "filter"
to make the image black-and-white.

Kind regards,
--
-- Marco Nijdam,         marco at west.nl
-- West Consulting B.V., Delftechpark 5, 2628 XJ  Delft, The Netherlands
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