HDF5: Use explicit mapping for VDS

tests/HDF5WritingTest.cpp

@@ -1344,3 +1344,100 @@ TEST_CASE("FileWriter_TIFF", "[HDF5][Full]") {
         REQUIRE(!file_set.GetZMQAddr());
     }
 }
+
+TEST_CASE("HDF5Objects_VDS_reverse_contiguous", "[HDF5][Unit]") {
+    {
+        RegisterHDF5Filter();
+
+        HDF5File file("scratch_vds_reverse_contiguous.h5", true);
+        HDF5Dcpl dcpl;
+        HDF5DataType data_type((int16_t) 0);
+        HDF5DataSpace full_space({5, 4, 3});
+
+        {
+            HDF5DataSpace source_space({2, 4, 3});
+            HDF5DataSpace virtual_space({5, 4, 3});
+            virtual_space.SelectHyperslab({0, 0, 0}, {2, 4, 3});
+            dcpl.SetVirtual("file_000001.h5", "/entry/data/data", source_space, virtual_space);
+        }
+
+        {
+            HDF5DataSpace source_space({3, 4, 3});
+            HDF5DataSpace virtual_space({5, 4, 3});
+            virtual_space.SelectHyperslab({2, 0, 0}, {3, 4, 3});
+            dcpl.SetVirtual("file_000002.h5", "/entry/data/data", source_space, virtual_space);
+        }
+
+        HDF5DataSet dataset(file, "/data", data_type, full_space, dcpl);
+
+        HDF5Dcpl read_dcpl(dataset);
+        auto mappings = read_dcpl.GetVirtualMappings();
+
+        REQUIRE(mappings.size() == 2);
+        REQUIRE(mappings[0].ContainsVirtualImage(0));
+        REQUIRE(mappings[0].ContainsVirtualImage(1));
+        REQUIRE(!mappings[0].ContainsVirtualImage(2));
+        CHECK(mappings[0].SourceImage(0) == 0);
+        CHECK(mappings[0].SourceImage(1) == 1);
+
+        REQUIRE(mappings[1].ContainsVirtualImage(2));
+        REQUIRE(mappings[1].ContainsVirtualImage(4));
+        CHECK(mappings[1].SourceImage(2) == 0);
+        CHECK(mappings[1].SourceImage(3) == 1);
+        CHECK(mappings[1].SourceImage(4) == 2);
+    }
+
+    remove("scratch_vds_reverse_contiguous.h5");
+    REQUIRE(H5Fget_obj_count(H5F_OBJ_ALL, H5F_OBJ_ALL) == 0);
+}
+
+TEST_CASE("HDF5Objects_VDS_reverse_strided", "[HDF5][Unit]") {
+    {
+        RegisterHDF5Filter();
+
+        HDF5File file("scratch_vds_reverse_strided.h5", true);
+        HDF5Dcpl dcpl;
+        HDF5DataType data_type((int16_t) 0);
+        HDF5DataSpace full_space({6, 4, 3});
+
+        {
+            HDF5DataSpace source_space({3, 4, 3});
+            HDF5DataSpace virtual_space({6, 4, 3});
+            virtual_space.SelectHyperslabWithStride({0, 0, 0}, {3, 4, 3}, {2, 1, 1});
+            dcpl.SetVirtual("file_even.h5", "/entry/data/data", source_space, virtual_space);
+        }
+
+        {
+            HDF5DataSpace source_space({3, 4, 3});
+            HDF5DataSpace virtual_space({6, 4, 3});
+            virtual_space.SelectHyperslabWithStride({1, 0, 0}, {3, 4, 3}, {2, 1, 1});
+            dcpl.SetVirtual("file_odd.h5", "/entry/data/data", source_space, virtual_space);
+        }
+
+        HDF5DataSet dataset(file, "/data", data_type, full_space, dcpl);
+
+        HDF5Dcpl read_dcpl(dataset);
+        auto mappings = read_dcpl.GetVirtualMappings();
+
+        REQUIRE(mappings.size() == 2);
+
+        REQUIRE(mappings[0].ContainsVirtualImage(0));
+        REQUIRE(mappings[0].ContainsVirtualImage(2));
+        REQUIRE(mappings[0].ContainsVirtualImage(4));
+        REQUIRE(!mappings[0].ContainsVirtualImage(1));
+        CHECK(mappings[0].SourceImage(0) == 0);
+        CHECK(mappings[0].SourceImage(2) == 1);
+        CHECK(mappings[0].SourceImage(4) == 2);
+
+        REQUIRE(mappings[1].ContainsVirtualImage(1));
+        REQUIRE(mappings[1].ContainsVirtualImage(3));
+        REQUIRE(mappings[1].ContainsVirtualImage(5));
+        REQUIRE(!mappings[1].ContainsVirtualImage(0));
+        CHECK(mappings[1].SourceImage(1) == 0);
+        CHECK(mappings[1].SourceImage(3) == 1);
+        CHECK(mappings[1].SourceImage(5) == 2);
+    }
+
+    remove("scratch_vds_reverse_strided.h5");
+    REQUIRE(H5Fget_obj_count(H5F_OBJ_ALL, H5F_OBJ_ALL) == 0);
+}