r.in.gdal/r.external: add basic support for GDALs GDT_Int8 (OSGeo#4256)

* add support for Int8 from GDAL >= 3.7

* add int8 test (skiped if GDAL < 3.7)

lib/raster/gdal.c

@@ -125,6 +125,10 @@ struct GDAL_link *Rast_get_gdal_link(const char *name, const char *mapset)
 
     switch (type) {
     case GDT_Byte:
+/* GDT_Int8 was introduced in GDAL 3.7 */
+#if GDAL_VERSION_NUM >= GDAL_COMPUTE_VERSION(3, 7, 0)
+    case GDT_Int8:
+#endif
     case GDT_Int16:
     case GDT_UInt16:
     case GDT_Int32:

lib/raster/get_row.c

@@ -11,6 +11,7 @@
    \author Original author CERL
  */
 
+#include <stdint.h>
 #include <string.h>
 #include <unistd.h>
 #include <sys/types.h>
@@ -368,6 +369,12 @@ static void gdal_values_int(int fd, const unsigned char *data,
         case GDT_Byte:
             c[i] = *(GByte *)d;
             break;
+/* GDT_Int8 was introduced in GDAL 3.7 */
+#if GDAL_VERSION_NUM >= GDAL_COMPUTE_VERSION(3, 7, 0)
+        case GDT_Int8:
+            c[i] = *(int8_t *)d;
+            break;
+#endif
         case GDT_Int16:
             c[i] = *(GInt16 *)d;
             break;

raster/r.external/link.c

@@ -30,6 +30,14 @@ void query_band(GDALRasterBandH hBand, const char *output,
         cellhd->format = 0;
         break;
 
+/* GDT_Int8 was introduced in GDAL 3.7 */
+#if GDAL_VERSION_NUM >= GDAL_COMPUTE_VERSION(3, 7, 0)
+    case GDT_Int8:
+        info->data_type = CELL_TYPE;
+        cellhd->format = 1;
+        break;
+#endif
+
     case GDT_Int16:
     case GDT_UInt16:
         info->data_type = CELL_TYPE;

raster/r.in.gdal/testsuite/data/int8.vrt

@@ -0,0 +1,20 @@
+<VRTDataset rasterXSize="24" rasterYSize="24">
+  <SRS dataAxisToSRSAxisMapping="1,2">PROJCS["NAD83(HARN) / North Carolina",GEOGCS["NAD83(HARN)",DATUM["NAD83_High_Accuracy_Reference_Network",SPHEROID["GRS 1980",6378137,298.257222101,AUTHORITY["EPSG","7019"]],AUTHORITY["EPSG","6152"]],PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],UNIT["degree",0.0174532925199433,AUTHORITY["EPSG","9122"]],AUTHORITY["EPSG","4152"]],PROJECTION["Lambert_Conformal_Conic_2SP"],PARAMETER["latitude_of_origin",33.75],PARAMETER["central_meridian",-79],PARAMETER["standard_parallel_1",36.1666666666667],PARAMETER["standard_parallel_2",34.3333333333333],PARAMETER["false_easting",609601.22],PARAMETER["false_northing",0],UNIT["metre",1,AUTHORITY["EPSG","9001"]],AXIS["Easting",EAST],AXIS["Northing",NORTH],AUTHORITY["EPSG","3358"]]</SRS>
+  <GeoTransform>  0.0000000000000000e+00,  1.0000000000000000e+00,  0.0000000000000000e+00,  2.4000000000000000e+01,  0.0000000000000000e+00, -1.0000000000000000e+00</GeoTransform>
+  <Metadata>
+    <MDI key="AREA_OR_POINT">Area</MDI>
+  </Metadata>
+  <Metadata domain="IMAGE_STRUCTURE">
+    <MDI key="INTERLEAVE">BAND</MDI>
+  </Metadata>
+  <VRTRasterBand dataType="Int8" band="1">
+    <ColorInterp>Gray</ColorInterp>
+    <SimpleSource>
+      <SourceFilename relativeToVRT="1">./int8.tif</SourceFilename>
+      <SourceBand>1</SourceBand>
+      <SourceProperties RasterXSize="24" RasterYSize="24" DataType="Int8" BlockXSize="24" BlockYSize="24" />
+      <SrcRect xOff="0" yOff="0" xSize="24" ySize="24" />
+      <DstRect xOff="0" yOff="0" xSize="24" ySize="24" />
+    </SimpleSource>
+  </VRTRasterBand>
+</VRTDataset>

raster/r.in.gdal/testsuite/test_r_in_gdal.py

@@ -3,6 +3,10 @@
 @author Soeren Gebbert
 """
 
+import unittest
+
+from subprocess import check_output
+
 from grass.gunittest.case import TestCase
 
 
@@ -306,6 +310,44 @@ def test_netCDF_3d_5(self):
 
         self.assertLooksLike(map_list, text_from_file)
 
+    @unittest.skipIf(
+        tuple(
+            map(
+                int,
+                check_output(["gdal-config", "--version"])
+                .decode("UTF8")
+                .split(".")[0:2],
+            )
+        )
+        < (3, 7),
+        "GDAL version too old. Int8 support was introduced in GDAL 3.7",
+    )
+    def test_int8_data(self):
+        """Test that Int8 VRTs are imported"""
+
+        self.assertModule(
+            "r.in.gdal",
+            input="data/int8.vrt",
+            output="test_gdal_import_map",
+        )
+
+        # Output of r.info
+        info_string = """north=24
+                       south=0
+                       east=24
+                       west=0
+                       nsres=1
+                       ewres=1
+                       rows=24
+                       cols=24
+                       cells=576
+                       datatype=CELL
+                       ncats=0"""
+
+        self.assertRasterFitsInfo(
+            raster="test_gdal_import_map", reference=info_string, precision=3
+        )
+
 
 class TestGdalImportFails(TestCase):
     def test_error_handling_1(self):