imagefusion: Workaround incrementing GCP attributes

src/geoinfo.cpp

@@ -320,8 +320,8 @@ void GeoInfo::addTo(GDALDataset* img) const {
         for (GCP const& gcp : gcps) {
             gdal_gcps.push_back(GDAL_GCP{const_cast<char*>(gcp.id.c_str()),
                                          const_cast<char*>(gcp.info.c_str()),
-                                         gcp.pixel,
-                                         gcp.line,
+                                         gcp.pixel - 1,  // workaround for incrementing dfGCPPixel on write
+                                         gcp.line - 1,   // workaround for incrementing dfGCPLine on write
                                          gcp.x,
                                          gcp.y,
                                          gcp.z});

tests/geoinfo_test.cpp

@@ -124,6 +124,10 @@ BOOST_AUTO_TEST_CASE(gcp)
     Image img{input_filename};
     img.write(output_filename, gi);
     GeoInfo gi_after{output_filename};
+    img.write(output_filename, gi_after);
+    gi_after = GeoInfo{output_filename};
+    img.write(output_filename, gi_after);
+    gi_after = GeoInfo{output_filename};
 
     // check if the GCP survived
     BOOST_CHECK_EQUAL(gi_after.gcps.size(), 3);