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WIA drivers.

Posted: Fri Jul 01, 2016 3:31 pm
by Alex
In this topic we will share our experience about WIA drivers.

Re: WIA drivers.

Posted: Fri Jul 01, 2016 3:37 pm
by Alex
Problem:
You have the "General failure" error when you are trying to acquire image from WIA driver.



How to reproduce:
  • Open the device (call the Device.Open method)
  • Check that feeder is enabled (get value of Device.DocumentFeeder.Enabled property)
  • Try to enable feeder (set value of Device.DocumentFeeder.Enabled property to True)
  • Acquire image from device (call the Device.Acquire method)


Conclusion:
WIA drivers have bug. WIA driver cannot acquire image from device if application tried to set the CAP_FEEDERENABLED capability to TRUE.

We do not want to change algorithm of the Device.HasFeeder property because Microsoft may fix the bug in the future. Also maybe not all WIA drivers have the bug.



Solution:
  • Do not get value of the Device.HasFeeder property if you have WIA driver
  • Do not set value of the DocumentFeeder.Enabled property to True if you have WIA driver

Re: WIA drivers.

Posted: Mon Jul 18, 2016 3:36 pm
by alexei
Hi,

Based on my unpleasant experience with the WIA driver I want to contribute with this thread.

Windows WIA driver in combination with EPSON GT-S55 problems:

1. During scanning you get a dialog and you only see the progress bar.
2. Device Manager only returns the last page.
3. Scanner has capability to skip blank pages, but when you set the capability (4404) the device Manager will return an error when setting this capability.
4. Sometimes when you display the scan preview as base64 the page is not vertically aligned, sometimes it shows a little bit tilt to the left.

It is better to use the vendor's twain drivers.

Regards,
Alexei