[sane-devel] question about SANE backend fill_buffer function

Gernot Hassenpflug aikishugyo at gmail.com
Tue Sep 7 10:47:18 UTC 2010

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?

Gernot Hassenpflug
ISP Asahi-Net: http://asahi-net.jp/en/
No.1 in Japan by customer satisfaction
(Nikkei News, 7 July 2010)

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