Add page re-flipping as an option

Flipping duplex scanners must flip the page in order to scan the back side
of the page.  With this option set (which is the default), the page is
flipped back to the original orientation.  This is important if you have
a stack of papers.  However, if you don't care if every page ends up
flipped compared to how it was loaded, turning this option off might save
some scanning time as the paper won't have to be pulled back through the
ADF mechanism a third time.

backend/avision.c

@@ -5665,7 +5665,8 @@ set_window (Avision_Scanner* s)
     {
       DBG (3, "set_window: non-interlaced duplex type (HP)\n");
       SET_BIT(cmd.window.avision.type.normal.bitset3, 0); /* DPLX 0x01 */
-      SET_BIT(cmd.window.avision.type.normal.bitset3, 1); /* FLIP 0x02 */
+      if (s->val[OPT_ADF_FLIP].w)
+        SET_BIT(cmd.window.avision.type.normal.bitset3, 1); /* FLIP 0x02 */
       SET_BIT(cmd.window.avision.type.normal.bitset3, 2); /* MIRR 0x04 */
     }
   }
@@ -6657,6 +6658,19 @@ init_options (Avision_Scanner* s)
   s->opt[OPT_PAPERLEN].constraint_type = SANE_CONSTRAINT_NONE;
   s->val[OPT_PAPERLEN].w     = SANE_FALSE;
   
+  /* ADF page flipping */
+  s->opt[OPT_ADF_FLIP].cap = SANE_CAP_SOFT_SELECT | SANE_CAP_SOFT_DETECT | SANE_CAP_AUTOMATIC | SANE_CAP_ADVANCED;
+  if (!(s->hw->hw->feature_type2 & AV_ADF_FLIPPING_DUPLEX && s->source_mode == AV_ADF_DUPLEX))
+    s->opt[OPT_ADF_FLIP].cap |= SANE_CAP_INACTIVE;
+  s->opt[OPT_ADF_FLIP].name = "flip-page";
+  s->opt[OPT_ADF_FLIP].title = "Flip document after duplex scanning";
+  s->opt[OPT_ADF_FLIP].desc = "Tells page-flipping document scanners to flip the paper back to its original orientation before dropping it in the output tray.  Turning this off might make scanning a little faster if you don't care about manually flipping the pages afterwards.";
+  s->opt[OPT_ADF_FLIP].type = SANE_TYPE_BOOL;
+  s->opt[OPT_ADF_FLIP].unit = SANE_UNIT_NONE;
+  s->opt[OPT_ADF_FLIP].size = sizeof(SANE_Word);
+  s->opt[OPT_ADF_FLIP].constraint_type = SANE_CONSTRAINT_NONE;
+  s->val[OPT_ADF_FLIP].w = SANE_TRUE;
+
   return SANE_STATUS_GOOD;
 }
 
@@ -7458,6 +7472,10 @@ reader_process (void *data)
   if ((dev->hw->feature_type2 & AV_ADF_FLIPPING_DUPLEX) && s->source_mode == AV_ADF_DUPLEX && s->page % 2) {
     /* front page of flipping duplex */
     if (exit_status == SANE_STATUS_EOF) {
+      if (s->val[OPT_ADF_FLIP].w) {
+        /* The page flip bit must be reset after every scan, but if the
+         * user doesn't care, there's no reason to reset.
+         */
         status = set_window (s);
         if (status != SANE_STATUS_GOOD) {
           DBG (1, "reader_process: set scan window command failed: %s\n",
@@ -7465,6 +7483,7 @@ reader_process (void *data)
           return status;
         }
       /* we can set anything here without fear because the process will terminate soon and take our changes with it */
+      }
       s->page += 1;
       s->params.lines = line;
       exit_status = reader_process (s);
@@ -8045,6 +8064,7 @@ sane_control_option (SANE_Handle handle, SANE_Int option,
 	case OPT_QSCAN:
 	case OPT_QCALIB:
 	case OPT_PAPERLEN:
+	case OPT_ADF_FLIP:
 	  *(SANE_Word*) val = s->val[option].w;
 	  return SANE_STATUS_GOOD;
 	  
@@ -8116,6 +8136,7 @@ sane_control_option (SANE_Handle handle, SANE_Int option,
 	case OPT_OVERSCAN_BOTTOM:
 	case OPT_BACKGROUND:
 	case OPT_PAPERLEN:
+	case OPT_ADF_FLIP:
 	  s->val[option].w = *(SANE_Word*) val;
 	  return SANE_STATUS_GOOD;
 	  
@@ -8156,6 +8177,12 @@ sane_control_option (SANE_Handle handle, SANE_Int option,
 	    SANE_FIX ( dev->inquiry_x_ranges[s->source_mode_dim]);
 	  dev->y_range.max =
 	    SANE_FIX ( dev->inquiry_y_ranges[s->source_mode_dim]);
+
+          if (s->hw->hw->feature_type2 & AV_ADF_FLIPPING_DUPLEX && s->source_mode == AV_ADF_DUPLEX) {
+            s->opt[OPT_ADF_FLIP].cap &= ~SANE_CAP_INACTIVE;
+          } else {
+            s->opt[OPT_ADF_FLIP].cap |= SANE_CAP_INACTIVE;
+          }
 	  
 	  if (info)
 	    *info |= SANE_INFO_RELOAD_OPTIONS | SANE_INFO_RELOAD_PARAMS;
@@ -8214,6 +8241,18 @@ sane_control_option (SANE_Handle handle, SANE_Int option,
 	    return status;
 	  }
 	} /* end switch option */
+    }
+  else if (action == SANE_ACTION_SET_AUTO)
+    {
+      if (!SANE_OPTION_IS_SETTABLE (cap))
+	return SANE_STATUS_INVAL;
+
+      switch (option)
+	{
+	case OPT_ADF_FLIP:
+	  s->val[option].w = SANE_TRUE;
+	  return SANE_STATUS_GOOD;
+	} /* end switch option */
     } /* end else SET_VALUE */
   return SANE_STATUS_INVAL;
 }

backend/avision.h

@@ -300,6 +300,7 @@ enum Avision_Option
   OPT_NVRAM,             /* retrieve NVRAM values as pretty printed text */
   
   OPT_PAPERLEN,          /* Use paper_length field to detect double feeds */
+  OPT_ADF_FLIP,          /* For flipping duplex, reflip the document */
 
   NUM_OPTIONS            /* must come last */
 };