Comment 57 for bug 550856

I believe the issue is with ADF only

My option are set as A4 scanning, ADF.

Running de debug mode, i can see the requests for options :

[+135,61s] DEBUG: scanner.vala:795: Option 6: name='tl-x' title='Top-left x' type=fixed size=4 unit=mm min=0,000000, max=215,899994, quant=0 cap=soft-select,soft-detect
[+135,61s] DEBUG: scanner.vala:798: Description: Top-left x position of scan area.
[+135,61s] DEBUG: scanner.vala:1002: sane_get_option_descriptor (7)
[+135,61s] DEBUG: scanner.vala:795: Option 7: name='tl-y' title='Top-left y' type=fixed size=4 unit=mm min=0,000000, max=355,599991, quant=0 cap=soft-select,soft-detect
[+135,61s] DEBUG: scanner.vala:798: Description: Top-left y position of scan area.
[+135,61s] DEBUG: scanner.vala:1002: sane_get_option_descriptor (8)
[+135,61s] DEBUG: scanner.vala:795: Option 8: name='br-x' title='Bottom-right x' type=fixed size=4 unit=mm min=0,000000, max=215,899994, quant=0 cap=soft-select,soft-detect
[+135,61s] DEBUG: scanner.vala:798: Description: Bottom-right x position of scan area.

Then it seems it issues a call for action :

[+135,61s] DEBUG: scanner.vala:602: sane_control_option (4, SANE_ACTION_SET_VALUE, source="ADF Duplex") -> (SANE_STATUS_GOOD, "ADF Duplex")
[+135,61s] DEBUG: scanner.vala:602: sane_control_option (3, SANE_ACTION_SET_VALUE, mode="Gray") -> (SANE_STATUS_GOOD, "Gray")
[+135,61s] DEBUG: scanner.vala:514: sane_control_option (2, SANE_ACTION_SET_VALUE, resolution=200) -> (SANE_STATUS_GOOD, 200)
[+135,61s] DEBUG: scanner.vala:554: sane_control_option (8, SANE_ACTION_SET_VALUE, br-x=210,000000) -> (SANE_STATUS_GOOD, 210,000000)
[+135,61s] DEBUG: scanner.vala:554: sane_control_option (9, SANE_ACTION_SET_VALUE, br-y=297,000000) -> (SANE_STATUS_GOOD, 297,000000)

This will work for flatbed, as the paper, whether A4 of Letter size, is left-aligned (it tl-x=0, which i guess is the default); however with ADF, Letter is centered while A4 paper is centered in he scanning area which is 21.6cm wide; hence there should be a margin of 0.3 cm on each side of the scanning aread

that for a flatbed, the offset for top left X should be 0 while for ADF, the A4 page is centered in the scanner area total width, ie, the top left X should be 6/2 = 3mm

Am I wrong, or, what is missing here, is a call to set "top left x" ie ,tl-x=3
to offset where the scan range should actually start when scanning A4 with ADF.