c# - WIA 2.0 WIA_DPS_DOCUMENT_HANDLING_STATUS doesn't seem to be updating - scanner specific? -

i have hp officejet pro 8600 plus all-in-one , using wia 2.0 implement own scanning ui , logic.

if read documentation here (https://msdn.microsoft.com/en-us/library/windows/hardware/ff551386(v=vs.85).aspx) correctly, looks feed_ready should update pages being scanned. seems people using check. have found following sample code in several posts:

                    //determine if there more pages waiting                     wia.property documenthandlingselect = null;                     wia.property documenthandlingstatus = null;                     foreach (wia.property prop in device.properties)                     {                     if (prop.propertyid == wia_properties.wia_dps_document_handling_select)                             documenthandlingselect = prop;                     if (prop.propertyid == wia_properties.wia_dps_document_handling_status)                             documenthandlingstatus = prop;                     }                     // assume there no more pages                     hasmorepages = false;                     // may not exist on flatbed scanner required feeder                     if (documenthandlingselect != null)                     {                         // check document feeder                         if ((convert.touint32(documenthandlingselect.get_value()) &                          wia_dps_document_handling_select.feeder) != 0)                         {                             hasmorepages = ((convert.touint32(documenthandlingstatus.get_value()) &                              wia_dps_document_handling_status.feed_ready) != 0);                         }                     } 

in code following check (which similar sample code above doing):

                ...connect _scanner                  foreach (property p in _scanner.properties)                 {                     if (p.name == wia_dps_document_handling_status)                     {                         value = p.get_value();                     }                 }                  images.add(dialog.showtransfer(_scanner.items[1], formatid.wiaformatjpeg, false) imagefile);                  foreach (property p in _scanner.properties)                 {                     if (p.name == wia_dps_document_handling_status)                     {                         value = p.get_value();                     }                 } 

here's seeing:

1. if have loaded page in scanner before connecting it, both get_value() return feed_ready.
2. if have not loaded page before connecting it, before first foreach loop (mimicking user might do), both get_value() not return feed_ready

in either case, i'd expect first foreach loop return feed_ready , second not return feed_ready since page has correctly been scanned.

is scanner specific? i.e. bad driver implementation hp? couldn't find sort of 'refresh' capability. also, samples have found seem indicate should work.

i tried set front_first | duplex handle duplex scanning wia_ips_document_handling_select, got out of range error. instead set feeder | duplex documentation seem feeder used on xp , obsolete on newer oses.

any insights? scanner specific, i.e. based on how implement driver? struck me sample code might have worked wia 1.0 not wia 2.0.