MAINT: Improve qdarkstyle logic

README.rst

@@ -88,12 +88,12 @@ For full functionality, some functions require:
 - `scikit-learn <https://scikit-learn.org/stable/>`__ ≥ 1.0
 - `Joblib <https://joblib.readthedocs.io/en/latest/index.html>`__ ≥ 0.15 (for parallelization)
 - `mne-qt-browser <https://github.com/mne-tools/mne-qt-browser>`__ ≥ 0.1 (for fast raw data visualization)
-- `Qt <https://www.qt.io>`__ ≥ 5.12 via one of the following bindings (for fast raw data visualization and interactive 3D visualization):
+- `Qt <https://www.qt.io>`__ ≥ 5.15 via one of the following bindings (for fast raw data visualization and interactive 3D visualization):
 
   - `PyQt6 <https://www.riverbankcomputing.com/software/pyqt/>`__ ≥ 6.0
   - `PySide6 <https://doc.qt.io/qtforpython-6/>`__ ≥ 6.0
-  - `PyQt5 <https://www.riverbankcomputing.com/software/pyqt/>`__ ≥ 5.12
-  - `PySide2 <https://doc.qt.io/qtforpython-6/gettingstarted/porting_from2.html>`__ ≥ 5.12
+  - `PyQt5 <https://www.riverbankcomputing.com/software/pyqt/>`__ ≥ 5.15
+  - `PySide2 <https://doc.qt.io/qtforpython-6/gettingstarted/porting_from2.html>`__ ≥ 5.15
 
 - `Numba <https://numba.pydata.org>`__ ≥ 0.54.0
 - `NiBabel <https://nipy.org/nibabel/>`__ ≥ 3.2.1

doc/changes/devel/dependency.rst

@@ -0,0 +1 @@
+The minimum supported version of Qt bindings is 5.15, by `Eric Larson`_.

mne/viz/backends/_utils.py

@@ -274,84 +274,42 @@ def _qt_detect_theme():
 def _qt_get_stylesheet(theme):
     _validate_type(theme, ("path-like",), "theme")
     theme = str(theme)
-    orig_theme = theme
-    system_theme = None
-    stylesheet = ""
-    extra_msg = ""
-    if theme == "auto":
-        theme = system_theme = _qt_detect_theme()
-    if theme in ("dark", "light"):
-        if system_theme is None:
-            system_theme = _qt_detect_theme()
-        qt_version, api = _check_qt_version(return_api=True)
-        # On macOS, we shouldn't need to set anything when the requested theme
-        # matches that of the current OS state
-        if sys.platform == "darwin":
-            extra_msg = f"when in {system_theme} mode on macOS"
-        # But before 5.13, we need to patch some mistakes
-        if sys.platform == "darwin" and theme == system_theme:
-            if theme == "dark" and _compare_version(qt_version, "<", "5.13"):
-                # Taken using "Digital Color Meter" on macOS 12.2.1 looking at
-                # Meld, and also adapting (MIT-licensed)
-                # https://github.com/ColinDuquesnoy/QDarkStyleSheet/blob/master/qdarkstyle/dark/style.qss  # noqa: E501
-                # Something around rgb(51, 51, 51) worked as the bgcolor here,
-                # but it's easy enough just to set it transparent and inherit
-                # the bgcolor of the window (which is the same). We also take
-                # the separator images from QDarkStyle (MIT).
-                icons_path = _qt_init_icons()
-                stylesheet = """\
-QStatusBar {
-  border: 1px solid rgb(76, 76, 75);
-  background: transparent;
-}
-QStatusBar QLabel {
-  background: transparent;
-}
-QToolBar {
-  background-color: transparent;
-  border-bottom: 1px solid rgb(99, 99, 99);
-}
-QToolBar::separator:horizontal {
-  width: 16px;
-  image: url("%(icons_path)s/toolbar_separator_horizontal@2x.png");
-}
-QToolBar::separator:vertical {
-  height: 16px;
-  image: url("%(icons_path)s/toolbar_separator_vertical@2x.png");
-}
-QToolBar::handle:horizontal {
-  width: 16px;
-  image: url("%(icons_path)s/toolbar_move_horizontal@2x.png");
-}
-QToolBar::handle:vertical {
-  height: 16px;
-  image: url("%(icons_path)s/toolbar_move_vertical@2x.png");
-}
-""" % dict(icons_path=icons_path)
+    stylesheet = ""  # no stylesheet
+    if theme in ("auto", "dark", "light"):
+        if theme == "auto":
+            return stylesheet
+        assert theme in ("dark", "light")
+        system_theme = _qt_detect_theme()
+        if theme == system_theme:
+            return stylesheet
+        _, api = _check_qt_version(return_api=True)
+        # On macOS or Qt 6, we shouldn't need to set anything when the requested
+        # theme matches that of the current OS state
+        try:
+            import qdarkstyle
+        except ModuleNotFoundError:
+            logger.info(
+                f'To use {theme} mode when in {system_theme} mode, "qdarkstyle" has'
+                "to be installed! You can install it with:\n"
+                "pip install qdarkstyle\n"
+            )
         else:
-            # Here we are on non-macOS (or on macOS but our sys theme does not
-            # match the requested theme)
-            if api in ("PySide6", "PyQt6"):
-                if orig_theme != "auto" and not (theme == system_theme == "light"):
-                    warn(
-                        f"Setting theme={repr(theme)} is not yet supported "
-                        f"for {api} in qdarkstyle, it will be ignored"
-                    )
+            if api in ("PySide6", "PyQt6") and _compare_version(
+                qdarkstyle.__version__, "<", "3.2.3"
+            ):
+                warn(
+                    f"Setting theme={repr(theme)} is not supported for {api} in "
+                    f"qdarkstyle {qdarkstyle.__version__}, it will be ignored. "
+                    "Consider upgrading qdarkstyle to >=3.2.3."
+                )
             else:
-                try:
-                    import qdarkstyle
-                except ModuleNotFoundError:
-                    logger.info(
-                        f'To use {theme} mode{extra_msg}, "qdarkstyle" has to '
-                        "be installed! You can install it with:\n"
-                        "pip install qdarkstyle\n"
-                    )
-                else:
-                    klass = getattr(
+                stylesheet = qdarkstyle.load_stylesheet(
+                    getattr(
                         getattr(qdarkstyle, theme).palette,
                         f"{theme.capitalize()}Palette",
                     )
-                    stylesheet = qdarkstyle.load_stylesheet(klass)
+                )
+        return stylesheet
     else:
         try:
             file = open(theme)
@@ -363,8 +321,7 @@ def _qt_get_stylesheet(theme):
         else:
             with file as fid:
                 stylesheet = fid.read()
-
-    return stylesheet
+        return stylesheet
 
 
 def _should_raise_window():