JP2KAK: Reads from overview band returns data from the main band

[yehiyam]

System: windows7 64 bit with gdal source version 1.8.1 SDK version v6.0 (v6_0-00828N)

When opening a .jp2 file with the kakadu driver (jp2kak) and trying to read a region from an overview band, the data is read from the main band.

To reproduce: Use the CSharp sample app GDALReadDirect GDALReadDirect utm.jp2 overview0.png 0

this will create an image the size of the first overview, but with the contents from the upper right quarter of the main band.

[yehiyam]

I've created a patch that I think resolves this issue (at least for my test cases it works fine).

[warmerdam]

I have been unable to reproduce the problem with dumpoverviews, but I see it does line by line io which skips the direct case. I'm not keen on another complete directio implementation for bands but I'm optimistic I can fix the problem at the dataset level.

[warmerdam]

Fixed in trunk (r23582) and 1.8 branch (r23583). The problem only occurs when reading overviews directly on overview bands via the "direct" api as oppposed to through the block cache.