[GDAL provider] Minimal support for GDT_Int8 of GDAL 3.7.0

Fixes #50907 GDAL 3.7.0 brings GDT_Int8, which triggers compiler warnings in QGIS due to those new enumeration values not being handled. We do a minimal handling of them, by exposing them as QGIS Int16 rasters A more ambitious fix would be to add proper Int8 support to QGIS.
qgis · Jan 27, 2023 · 5986a80 · 5986a80
1 parent d33b875
commit 5986a80
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diff --git a/src/core/providers/gdal/qgsgdalprovider.cpp b/src/core/providers/gdal/qgsgdalprovider.cpp
@@ -1427,6 +1427,16 @@ double QgsGdalProvider::sample( const QgsPointXY &point, int band, bool *ok, con
   const GDALDataType dataType {GDALGetRasterDataType( hBand )};
   switch ( dataType )
   {
+#if GDAL_VERSION_NUM >= GDAL_COMPUTE_VERSION(3,7,0)
+    case GDT_Int8:
+    {
+      int8_t tempVal{0};
+      err = GDALRasterIO( hBand, GF_Read, col, row, 1, 1,
+                          &tempVal, 1, 1, dataType, 0, 0 );
+      value = static_cast<double>( tempVal );
+      break;
+    }
+#endif
     case GDT_Byte:
     {
       unsigned char tempVal{0};
@@ -3312,6 +3322,9 @@ void QgsGdalProvider::initBaseDataset()
         case GDT_Unknown:
         case GDT_TypeCount:
           break;
+#if GDAL_VERSION_NUM >= GDAL_COMPUTE_VERSION(3,7,0)
+        case GDT_Int8:
+#endif
         case GDT_Byte:
         case GDT_UInt16:
         case GDT_Int16:
@@ -3335,6 +3348,12 @@ void QgsGdalProvider::initBaseDataset()
       }
     }
 
+#if GDAL_VERSION_NUM >= GDAL_COMPUTE_VERSION(3,7,0)
+    if ( myGdalDataType == GDT_Int8 )
+    {
+      myGdalDataType = GDT_Int16;
+    }
+#endif
 #if GDAL_VERSION_NUM >= GDAL_COMPUTE_VERSION(3,5,0)
     if ( myGdalDataType == GDT_Int64 || myGdalDataType == GDT_UInt64 )
     {
@@ -3410,6 +3429,10 @@ bool QgsGdalProvider::write( void *data, int band, int width, int height, int xO
     return false;
   }
   GDALDataType gdalDataType = GDALGetRasterDataType( rasterBand );
+#if GDAL_VERSION_NUM >= GDAL_COMPUTE_VERSION(3,7,0)
+  if ( gdalDataType == GDT_Int8 )
+    gdalDataType = GDT_Int16;
+#endif
 #if GDAL_VERSION_NUM >= GDAL_COMPUTE_VERSION(3,5,0)
   if ( gdalDataType == GDT_Int64 || gdalDataType == GDT_UInt64 )
     gdalDataType = GDT_Float64;

diff --git a/src/core/providers/gdal/qgsgdalproviderbase.cpp b/src/core/providers/gdal/qgsgdalproviderbase.cpp
@@ -152,6 +152,11 @@ Qgis::DataType QgsGdalProviderBase::dataTypeFromGdal( const GDALDataType gdalDat
 {
   switch ( gdalDataType )
   {
+#if GDAL_VERSION_NUM >= GDAL_COMPUTE_VERSION(3,7,0)
+    case GDT_Int8:
+      // Promote to Int16 due to lack of native Qgis data type for Int8
+      return Qgis::DataType::Int16;
+#endif
     case GDT_Byte:
       return Qgis::DataType::Byte;
     case GDT_UInt16:

diff --git a/tests/src/python/test_provider_gdal.py b/tests/src/python/test_provider_gdal.py
@@ -273,6 +273,42 @@ def testSanitizeVRT(self):
 
         assert 'OverviewList' not in open(vrtfilename, 'rt').read()
 
+    @unittest.skipIf(int(gdal.VersionInfo('VERSION_NUM')) < GDAL_COMPUTE_VERSION(3, 7, 0), "GDAL 3.7.0 required")
+    def testInt8(self):
+        """Test Int8 support"""
+
+        tmp_dir = QTemporaryDir()
+        tmpfile = os.path.join(tmp_dir.path(), 'testInt8.tif')
+        ds = gdal.GetDriverByName('GTiff').Create(tmpfile, 2, 2, 1, gdal.GDT_Int8)
+        ds.WriteRaster(0, 0, 2, 2, struct.pack('b' * 4, 1, 127, 0, -128))
+        ds = None
+
+        raster_layer = QgsRasterLayer(tmpfile, 'test')
+        self.assertTrue(raster_layer.isValid())
+        self.assertEqual(raster_layer.dataProvider().dataType(1), Qgis.Int16)
+
+        extent = raster_layer.extent()
+        block = raster_layer.dataProvider().block(1, extent, 2, 2)
+
+        full_content = [1, 127, 0, -128]
+        self.checkBlockContents(block, full_content)
+
+        pos = QgsPointXY(0, 0)
+        value_sample = raster_layer.dataProvider().sample(pos, 1)[0]
+        self.assertEqual(value_sample, full_content[0])
+
+        pos = QgsPointXY(1, 0)
+        value_sample = raster_layer.dataProvider().sample(pos, 1)[0]
+        self.assertEqual(value_sample, full_content[1])
+
+        pos = QgsPointXY(0, -1)
+        value_sample = raster_layer.dataProvider().sample(pos, 1)[0]
+        self.assertEqual(value_sample, full_content[2])
+
+        pos = QgsPointXY(1, -1)
+        value_sample = raster_layer.dataProvider().sample(pos, 1)[0]
+        self.assertEqual(value_sample, full_content[3])
+
 
 if __name__ == '__main__':
     unittest.main()