Add int8 (since gdal 3.7.0) (#127)

godal.go

@@ -45,6 +45,9 @@ const (
 	Byte = DataType(C.GDT_Byte)
 	//UInt16 DataType
 	UInt16 = DataType(C.GDT_UInt16)
+	//Int8 DataType (GDAL>=3.7.0)
+	// [RFC 87]: https://gdal.org/development/rfc/rfc87_signed_int8.html
+	Int8 = DataType(C.GDT_Int8)
 	//Int16 DataType
 	Int16 = DataType(C.GDT_Int16)
 	//UInt32 DataType
@@ -89,7 +92,7 @@ func (dtype DataType) String() string {
 // Size retruns the number of bytes needed for one instance of DataType
 func (dtype DataType) Size() int {
 	switch dtype {
-	case Byte:
+	case Byte, Int8:
 		return 1
 	case Int16, UInt16:
 		return 2
@@ -1780,6 +1783,8 @@ func bufferType(buffer interface{}) DataType {
 	switch buffer.(type) {
 	case []byte:
 		return Byte
+	case []int8:
+		return Int8
 	case []int16:
 		return Int16
 	case []uint16:
@@ -1813,6 +1818,9 @@ func cBuffer(buffer interface{}, minsize int) unsafe.Pointer {
 	case []byte:
 		sizecheck(len(buf))
 		return unsafe.Pointer(&buf[0])
+	case []int8:
+		sizecheck(len(buf))
+		return unsafe.Pointer(&buf[0])
 	case []int16:
 		sizecheck(len(buf))
 		return unsafe.Pointer(&buf[0])

godal.h

@@ -27,6 +27,12 @@
 	#error "this code is only compatible with gdal version >= 3.0"
 #endif
 
+#if GDAL_VERSION_NUM < GDAL_COMPUTE_VERSION(3, 7, 0)
+typedef enum {
+    /*! 8-bit signed integer (GDAL >= 3.7) */ GDT_Int8 = 14
+} FutureGDALDataType;
+#endif
+
 #ifdef __cplusplus
 extern "C" {
 #endif

godal_test.go

@@ -77,6 +77,12 @@ func TestCBuffer(t *testing.T) {
 	assert.Equal(t, 1, bufferType(buf).Size())
 	assert.Panics(t, func() { cBuffer(buf, 101) })
 
+	buf = make([]int8, 100)
+	_ = cBuffer(buf, 100)
+	assert.Equal(t, Int8, bufferType(buf))
+	assert.Equal(t, 1, bufferType(buf).Size())
+	assert.Panics(t, func() { cBuffer(buf, 101) })
+
 	buf = make([]int16, 100)
 	_ = cBuffer(buf, 100)
 	assert.Equal(t, Int16, bufferType(buf))
@@ -223,6 +229,19 @@ func TestCreate(t *testing.T) {
 	if st1.Size() == st2.Size() {
 		t.Errorf("sizes: %d/%d", st1.Size(), st2.Size())
 	}
+
+	ehc = eh()
+	tmpname3 := tempfile()
+	defer os.Remove(tmpname3)
+	ds, err = Create(GTiff, tmpname3, 1, Int8, 20, 20, ErrLogger(ehc.ErrorHandler))
+	if CheckMinVersion(3, 7, 0) {
+		assert.NoError(t, err)
+
+		err = ds.Close(ErrLogger(ehc.ErrorHandler))
+		assert.NoError(t, err)
+	} else {
+	        assert.Error(t, err, "godal.Int8 is not supported with GDAL<3.7.0, but godal.Create did not return an error")
+	}
 }
 
 func TestRegisterDrivers(t *testing.T) {