[sane-devel] question about SANE backend fill_buffer function

[Gernot Hassenpflug]

Dear all,

I am working on the pixma backend for Canon devices (variation:
pixma_mp150.c), and have a question about registration of pixels in
the y dimension.

Each backend I believe has variations on a <filename>_fill_buffer
function called between <file>_scan and <>_finish_scan.

The function reads sections of data from the scanner, and processes it
line by line. Thus, pixels can be reorganized in the x-dimension.

I am not sure if the amount of data read at once is controllable.

I now have a problem where the pixels also need to be rearranged
vertically. In particular, the first half of a line corresponds to the
second half of a line much further along in the data.

Is there any backend that has support for such processing, that I can
look at for help? Or have I misunderstood what can be done with the
current mp150_fill_buffer function in pixma_mp150.c?

Regards,
Gernot Hassenpflug
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