genesys: Add a way to specify output pixel offset

backend/genesys/low.cpp

@@ -994,6 +994,7 @@ void compute_session(const Genesys_Device* dev, ScanSession& s, const Genesys_Se
     // after all adjustments on the optical pixels have been made, compute the number of pixels
     // to retrieve from the chip
     s.output_pixels = (s.optical_pixels * s.output_resolution) / s.optical_resolution;
+    s.output_startx = s.params.startx + sensor.output_pixel_offset;
 
     s.num_staggered_lines = 0;
     if (!has_flag(s.params.flags, ScanFlag::IGNORE_STAGGER_OFFSET))

backend/genesys/sensor.cpp

@@ -130,6 +130,7 @@ std::ostream& operator<<(std::ostream& out, const Genesys_Sensor& sensor)
         << "    ccd_size_divisor: " << sensor.ccd_size_divisor << '\n'
         << "    shading_factor: " << sensor.shading_factor << '\n'
         << "    pixel_count_ratio: " << sensor.pixel_count_ratio << '\n'
+        << "    output_pixel_offset: " << sensor.output_pixel_offset << '\n'
         << "    black_pixels: " << sensor.black_pixels << '\n'
         << "    dummy_pixel: " << sensor.dummy_pixel << '\n'
         << "    ccd_start_xoffset: " << sensor.ccd_start_xoffset << '\n'

backend/genesys/sensor.h

@@ -290,6 +290,9 @@ struct Genesys_Sensor {
     // the scanner.
     Ratio pixel_count_ratio = Ratio{1, 1};
 
+    // The offset in pixels in terms of scan resolution that needs to be applied to scan position.
+    unsigned output_pixel_offset = 0;
+
     int black_pixels = 0;
     // value of the dummy register
     int dummy_pixel = 0;
@@ -365,6 +368,7 @@ struct Genesys_Sensor {
             ccd_size_divisor == other.ccd_size_divisor &&
             shading_factor == other.shading_factor &&
             pixel_count_ratio == other.pixel_count_ratio &&
+            output_pixel_offset == other.output_pixel_offset &&
             black_pixels == other.black_pixels &&
             dummy_pixel == other.dummy_pixel &&
             ccd_start_xoffset == other.ccd_start_xoffset &&
@@ -393,6 +397,7 @@ void serialize(Stream& str, Genesys_Sensor& x)
     serialize(str, x.shading_resolution);
     serialize(str, x.ccd_size_divisor);
     serialize(str, x.shading_factor);
+    serialize(str, x.output_pixel_offset);
     serialize(str, x.pixel_count_ratio);
     serialize(str, x.black_pixels);
     serialize(str, x.dummy_pixel);

backend/genesys/settings.cpp

@@ -103,6 +103,7 @@ bool ScanSession::operator==(const ScanSession& other) const
         optical_pixels_raw == other.optical_pixels_raw &&
         optical_line_count == other.optical_line_count &&
         output_resolution == other.output_resolution &&
+        output_startx == other.output_startx &&
         output_pixels == other.output_pixels &&
         output_channel_bytes == other.output_channel_bytes &&
         output_line_bytes == other.output_line_bytes &&
@@ -141,6 +142,7 @@ std::ostream& operator<<(std::ostream& out, const ScanSession& session)
         << "    optical_pixels_raw: " << session.optical_pixels_raw << '\n'
         << "    optical_line_count: " << session.optical_line_count << '\n'
         << "    output_resolution: " << session.output_resolution << '\n'
+        << "    output_startx: " << session.output_startx << '\n'
         << "    output_pixels: " << session.output_pixels << '\n'
         << "    output_line_bytes: " << session.output_line_bytes << '\n'
         << "    output_line_bytes_raw: " << session.output_line_bytes_raw << '\n'

backend/genesys/settings.h

@@ -233,6 +233,9 @@ struct ScanSession {
     // gl843-only
     unsigned output_resolution = 0;
 
+    // the offset in pixels from the beginning of output data
+    unsigned output_startx = 0;
+
     // the number of pixels in output data (after desegmentation)
     unsigned output_pixels = 0;
 
@@ -346,6 +349,7 @@ void serialize(Stream& str, ScanSession& x)
     serialize(str, x.optical_pixels_raw);
     serialize(str, x.optical_line_count);
     serialize(str, x.output_resolution);
+    serialize(str, x.output_startx);
     serialize(str, x.output_pixels);
     serialize(str, x.output_channel_bytes);
     serialize(str, x.output_line_bytes);