[Geotools-devel] Using ImageIO via JAI (vs. directly)

[Saul F. <Sau...@st...>]

Hey Simone,

I've read through the ArcGrid raster example as well as other 
documentation, and I'm pretty clear on why and how to create an ImageIO 
plugin.  It'll take a little "stretching" of the traditional semantics 
of the model to make it fit pulling images from a database, but it seems 
that the API was largely designed to do this.

My one question is about this line in ArcGridReader.java:

RenderedOp asciiCoverage = JAI.create("ImageRead", pbjImageRead, hints);


I understand what this does, but I'm just curious as to why you decided 
to do it *this* way.  Couldn't you have just as easily called this 
(assuming that you'd created an appropriate ImageReadParam object)?

readerSPI.createReaderInstance().read(imageIndex, param);


Is that one "JAI" line the "JAI special sauce" that links the whole 
thing into the wacky world of JAI?  Is that the line that gives you 
cached image tiles, stream-able PlanarImages and all the other JAI 
goodness that you mentioned in our breakout a while ago (link below)?

http://docs.codehaus.org/display/GEOS/2006/07/27/Breakout+Coverage+Plugin+IRC+meeting+7-27-2006


Not that this really changes any implementation details for me, just 
curious about that bit.


Thanks,
--saul