How to set up the TWAIN only scan the paper on the back

[Richard]

Such as the title, I use Twain to do a project, do not use the Twain interface for scanning, but through the parameter settings to achieve.
Obtain the value of CAP_DUPLEX I can determine whether the scanner supports duplex scanning.By setting CAP_DUPLEXENABLED I scanner to duplex scanning.
How do I make the scanner scan only the back of the paper?

if anyone have a solution？

[MarkM]

Not all scanners support rear only scanning as a negotiable item. One way around this is to do the following (this assumes that there’s no blank image detection):

1) negotiate capabilities including duplexenabled
2) call dat_userinterface / msg_enableds
3) process msg_xferready
4) call dat_pendingxfers / msg_endxfer (this discards the front image)
5) transfer the rear image
6) if tw_pendingxfers.count != 0, go to step 4
7) call dat_userinterface / msg_disableds

Alternatively, if the driver is TWAIN 2.0 or higher, then you might be able to use CAP_CAMERAENBLED to turn the front camera off in concert with DAT_FILESYSTEM / MSG_CHANGEDIRECTORY (to address the desired camera), or with CAP_CAMERASIDE (same idea, a little easier to use).

[platomoda]

You can use TwainX ActiveX to achieve it. Get it now from http://www.file-expert.com/twainx-activex.htm

[Author]

Posts