<br>Hi ,<br><br>With your help,I have achieved duplex ADF scan in our backend with sane-backends 1.0.19 and XSane 0.995. Xsane could get front image and back image of a paper at the same time while scanning with ADF.<br><br>
I save back image in a buffer allocated by my backends then Xsane read a back image after XSane have get a whole front image.<br><br> Below suggestion is from m. allan noah:<br><br>1. from the frontend perspective, duplex is no different from simplex<br>
adf, there are just more images.<br><br>2. i have never gotten xsane's multi-page mode to work, i use<br>'scanimage -b' or 'scanadf' command line tools<br><br>3. there are several other backends which support duplex scans.<br>
fujitsu, avision, epjitsu come to mind. You could look at their code<br>for suggestions, but then your code becomes a derivative work, and you<br>must release it also under the GPL.<br><br>4. The way to write your code depends on the scanner. If the scanner<br>
has enough memory to buffer the back side data until after the<br>front-side has been read, then you just read them sequentially. if the<br>scanner sends back the data interlaced, then you must buffer the back<br>side in memory until the front side has been sent to front-end, then<br>
read back side from buffer. the fujitsu backend demonstrates both of<br>these.<br><br>5. be aware that a proper front-end in batch mode will call<br>sane_start() at the beginning of each page, but only call sane_cancel<br>
after the last page returns SANE_STATUS_NO_DOCS.<br>...<br><br>
Thank you.<br><br>