[Gdal-dev] IRasterIO in Dataset

[Frank Warmerdam]

Fu Chen wrote:
> Frank,
> Yeah, this code is more safe. Thanks.
> But I find the ecw supersample is very slow indeed when my little browser 
 > to set the zoom ratio more than 1:1. Is there any reason?

Fu Chen,

For some reason the ECW libraries won't do supersampling.  I could try and
implement it directly within the ECW driver but that is lots of work, so
to be safe (and lazy) I force things through generic level code reading
full scanlines from the ECW driver when supersampling.

The result is terribly expensive in IO.

It could be fixed, but would be a fair touch of work to do properly.

Later,

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