fixes for python <3.9

Author: vld-codra

plotpy/mathutils/colormaps.py

@@ -6,7 +6,7 @@
 #
 # Licensed under the terms of the BSD 3-Clause
 # (see plotpy/LICENSE for details)
-
+from __future__ import annotations
 
 import json
 import os

plotpy/styles/image.py

@@ -1,4 +1,5 @@
 # -*- coding: utf-8 -*-
+from __future__ import annotations
 
 from typing import Callable
 

plotpy/tests/tools/test_downsample_curve.py

@@ -11,6 +11,8 @@
 
 # guitest: show
 
+from __future__ import annotations
+
 from typing import Any
 
 from guidata.qthelpers import exec_dialog, qt_app_context

plotpy/tools/image.py

@@ -556,7 +556,7 @@ def activate_cmap(
             cmap: Cmap to apply for currently selected images. If None, the tool's
             active colormap will be used. Defaults to None.
         """
-        assert isinstance(cmap, QAction | str | CustomQwtLinearColormap | None)
+        assert isinstance(cmap, (QAction, str, CustomQwtLinearColormap)) or cmap is None
         if isinstance(cmap, QAction):
             self._active_colormap = cmap.data()  # type: ignore
         elif isinstance(cmap, str):

plotpy/widgets/colormap_widget.py

@@ -7,7 +7,7 @@
 """
 from __future__ import annotations
 
-from typing import Sequence, TypeVar, Union
+from typing import Sequence, Tuple, TypeVar, Union
 
 import numpy as np
 import qtpy.QtCore as QC
@@ -22,7 +22,7 @@
 
 ColorTypeT = TypeVar("ColorTypeT", bound=Union[QG.QColor, int])
 QColorInitTypes = Union[
-    QG.QColor, int, tuple[int, int, int, int], str, QC.Qt.GlobalColor, None
+    QG.QColor, int, Tuple[int, int, int, int], str, QC.Qt.GlobalColor, None
 ]