fix Python 3.7 compatibility

src/extract_otp_secrets.py

@@ -240,11 +240,13 @@ def cv2_draw_box(img: Any, raw_pts: Any, color: ColorBGR) -> Any:
 
 # TODO use cv2 types if available
 def cv2_print_text(img: Any, text: str, line_number: int, position: TextPosition, color: ColorBGR, opposite_len: Optional[int] = None) -> None:
-    text_dim, _ = cv2.getTextSize(text, FONT, FONT_SCALE, FONT_THICKNESS)
     window_dim = cv2.getWindowImageRect(WINDOW_NAME)
-    out_text = text \
-        if not opposite_len or (actual_width := text_dim[TEXT_WIDTH] + opposite_len * CHAR_DX + 4 * BORDER) <= window_dim[WINDOW_WIDTH] \
-        else text[:(window_dim[WINDOW_WIDTH] - actual_width) // CHAR_DX] + '.'
+    out_text = text
+    if opposite_len:
+        text_dim, _ = cv2.getTextSize(out_text, FONT, FONT_SCALE, FONT_THICKNESS)
+        actual_width = text_dim[TEXT_WIDTH] + opposite_len * CHAR_DX + 4 * BORDER
+        if actual_width >= window_dim[WINDOW_WIDTH]:
+            out_text = out_text[:(window_dim[WINDOW_WIDTH] - actual_width) // CHAR_DX] + '.'
     text_dim, _ = cv2.getTextSize(out_text, FONT, FONT_SCALE, FONT_THICKNESS)
     if position == TextPosition.LEFT:
         pos = BORDER, START_Y + line_number * FONT_DY

tests/extract_otp_secrets_test.py

@@ -413,8 +413,8 @@ def test_extract_verbose(verbose_level: str, color: str, capsys: pytest.CaptureF
     # Assert
     captured = capsys.readouterr()
 
-    expected_stdout = normalize_verbose_text(read_file_to_str(f'tests/data/print_verbose_output{color}{verbose_level}.txt'), actual_relaxed := relaxed or sys.implementation.name == 'pypy')
-    actual_stdout = normalize_verbose_text(captured.out, actual_relaxed)
+    expected_stdout = normalize_verbose_text(read_file_to_str(f'tests/data/print_verbose_output{color}{verbose_level}.txt'), relaxed or sys.implementation.name == 'pypy')
+    actual_stdout = normalize_verbose_text(captured.out, relaxed or sys.implementation.name == 'pypy')
 
     assert actual_stdout == expected_stdout
     assert captured.err == ''