PICARD-2300: Add qt's stylehints to theme.py for a consistent exp. across platforms

picard/__init__.py

@@ -42,7 +42,7 @@
 PICARD_DISPLAY_NAME = "MusicBrainz Picard"
 PICARD_APP_ID = "org.musicbrainz.Picard"
 PICARD_DESKTOP_NAME = PICARD_APP_ID + ".desktop"
-PICARD_VERSION = Version(3, 0, 0, 'dev', 6)
+PICARD_VERSION = Version(3, 0, 0, 'dev', 7)
 
 
 # optional build version

picard/config_upgrade.py

@@ -62,6 +62,8 @@
     VersionError,
 )
 
+from picard.ui.theme import UiTheme
+
 
 # All upgrade functions have to start with following prefix
 UPGRADE_FUNCTION_PREFIX = 'upgrade_to_v'
@@ -383,11 +385,9 @@ def upgrade_to_v2_6_0beta2(config):
 
 def upgrade_to_v2_6_0beta3(config):
     """Replace use_system_theme with ui_theme options"""
-    from picard.ui.theme import UiTheme
-
     _s = config.setting
     if _s.value('use_system_theme', BoolOption):
-        _s['ui_theme'] = str(UiTheme.SYSTEM)
+        _s['ui_theme'] = 'system'
     _s.remove('use_system_theme')
 
 
@@ -575,6 +575,12 @@ def upgrade_to_v3_0_0dev6(config):
     config.setting['standardize_vocals'] = standardize_instruments_and_vocals
 
 
+def upgrade_to_v3_0_0dev7(config):
+    """Change theme option SYSTEM to DEFAULT"""
+    if config.setting['ui_theme'] == "system":
+        config.setting['ui_theme'] = UiTheme.DEFAULT
+
+
 def rename_option(config, old_opt, new_opt, option_type, default):
     _s = config.setting
     if old_opt in _s:

picard/ui/options/interface.py

@@ -97,10 +97,6 @@ class InterfaceOptionsPage(OptionsPage):
             'label': N_("Light"),
             'desc': N_("A light display theme"),
         },
-        UiTheme.SYSTEM: {
-            'label': N_("System"),
-            'desc': N_("The Qt6 theme configured in the desktop environment"),
-        },
     }
 
     def __init__(self, parent=None):
@@ -181,13 +177,6 @@ def save(self):
         notes = []
         if new_theme_setting != config.setting['ui_theme']:
             warnings.append(_("You have changed the application theme."))
-            if new_theme_setting == str(UiTheme.SYSTEM):
-                notes.append(
-                    _(
-                        'Please note that using the system theme might cause the user interface to be not shown correctly. '
-                        'If this is the case select the "Default" theme option to use Picard\'s default theme again.'
-                    )
-                )
             config.setting['ui_theme'] = new_theme_setting
         if new_language != config.setting['ui_language']:
             config.setting['ui_language'] = new_language

picard/ui/theme.py

@@ -86,7 +86,6 @@ class UiTheme(Enum):
     DEFAULT = 'default'
     DARK = 'dark'
     LIGHT = 'light'
-    SYSTEM = 'system'
 
     def __str__(self):
         return self.value
@@ -96,11 +95,25 @@ def _missing_(cls, value):
         return cls.DEFAULT
 
 
-AVAILABLE_UI_THEMES = [UiTheme.DEFAULT]
-if IS_WIN or IS_MACOS:
-    AVAILABLE_UI_THEMES.extend([UiTheme.LIGHT, UiTheme.DARK])
-elif not IS_HAIKU:
-    AVAILABLE_UI_THEMES.extend([UiTheme.SYSTEM])
+def get_style_hints() -> QtGui.QStyleHints | None:
+    """Get style hints from QGuiApplication, returning None if unavailable."""
+    return QtGui.QGuiApplication.styleHints()
+
+
+def _style_hints_available() -> bool:
+    """Check if style hints are available on the current system."""
+    return get_style_hints() is not None
+
+
+# Theme availability based on platform capabilities
+if IS_HAIKU:
+    # Haiku doesn't support themes - UI is hidden anyway, but keep empty for consistency
+    AVAILABLE_UI_THEMES = []
+elif IS_WIN or IS_MACOS or _style_hints_available():
+    AVAILABLE_UI_THEMES = [UiTheme.DEFAULT, UiTheme.LIGHT, UiTheme.DARK]
+else:
+    # Use only default theme on platforms without style hints
+    AVAILABLE_UI_THEMES = [UiTheme.DEFAULT]
 
 
 class MacOverrideStyle(QtWidgets.QProxyStyle):
@@ -116,10 +129,51 @@ def styleHint(self, hint, option, widget, returnData):
         return super().styleHint(hint, option, widget, returnData)
 
 
+def apply_dark_palette_colors(palette):
+    """Apply dark palette colors to the given palette."""
+    for key, value in DARK_PALETTE_COLORS.items():
+        if isinstance(key, tuple):
+            group, role = key
+            palette.setColor(group, role, value)
+        else:
+            palette.setColor(key, value)
+
+
+def set_color_scheme(color_scheme: QtCore.Qt.ColorScheme):
+    """Set the color scheme using style hints if available.
+
+    Args:
+        color_scheme: The Qt color scheme to set
+    """
+    style_hints = get_style_hints()
+    if style_hints is not None:
+        style_hints.setColorScheme(color_scheme)
+
+
+def apply_dark_theme_to_palette(palette: QtGui.QPalette):
+    """Apply dark theme colors to the given palette using Qt's color scheme or manual fallback.
+
+    This method tries to use Qt's built-in color scheme first, and falls back to
+    manually applying dark colors if style hints are unavailable.
+
+    Args:
+        palette: The palette to apply dark colors to
+    """
+    style_hints = get_style_hints()
+    if style_hints is not None:
+        style_hints.setColorScheme(QtCore.Qt.ColorScheme.Dark)
+        # Test whether the change was successful
+        if style_hints.colorScheme() == QtCore.Qt.ColorScheme.Dark:
+            return
+    # Fall back to manually applying dark colors
+    apply_dark_palette_colors(palette)
+
+
 class BaseTheme:
     def __init__(self):
-        self._dark_theme = False
         self._loaded_config_theme = UiTheme.DEFAULT
+        self._dark_theme = False
+        self._accent_color = None
         # Registry of dark mode detection strategies for Linux DEs
         self._dark_mode_strategies = get_linux_dark_mode_strategies()
 
@@ -137,8 +191,8 @@ def setup(self, app):
         self._loaded_config_theme = UiTheme(config.setting['ui_theme'])
 
         # Use the new fusion style from PyQt6 for a modern and consistent look
-        # across all OSes.
-        if not IS_MACOS and not IS_HAIKU and self._loaded_config_theme != UiTheme.SYSTEM:
+        # across all OSes, except for macOS and Haiku.
+        if not IS_MACOS and not IS_HAIKU:
             app.setStyle('Fusion')
         elif IS_MACOS:
             app.setStyle(MacOverrideStyle(app.style()))
@@ -147,32 +201,40 @@ def setup(self, app):
             'QGroupBox::title { /* PICARD-1206, Qt bug workaround */ }',
         )
 
+        # Set color scheme based on theme configuration
+        style_hints = get_style_hints()
+        if style_hints is not None:
+            if self._loaded_config_theme == UiTheme.DARK:
+                set_color_scheme(QtCore.Qt.ColorScheme.Dark)
+            elif self._loaded_config_theme == UiTheme.LIGHT:
+                set_color_scheme(QtCore.Qt.ColorScheme.Light)
+            else:
+                # For DEFAULT theme, let Qt follow system settings
+                set_color_scheme(QtCore.Qt.ColorScheme.Unknown)
+
         palette = QtGui.QPalette(app.palette())
         base_color = palette.color(QtGui.QPalette.ColorGroup.Active, QtGui.QPalette.ColorRole.Base)
         self._dark_theme = base_color.lightness() < 128
         self._accent_color = None
         if self._dark_theme:
             self._accent_color = palette.color(QtGui.QPalette.ColorGroup.Active, QtGui.QPalette.ColorRole.Highlight)
 
-        # Linux-specific: If SYSTEM theme, try to detect system dark mode
-        # Do not apply override if already dark theme
+        # Linux-specific: If DEFAULT theme, try to detect system dark mode
+        # Do not apply override if already dark theme, or if a subclass already
+        # determined a dark theme state (e.g., WindowsTheme via registry on tests).
         is_dark_theme = self.is_dark_theme
         if (
             not self._dark_theme
+            and not is_dark_theme
             and not IS_WIN
             and not IS_MACOS
             and not IS_HAIKU
-            and self._loaded_config_theme == UiTheme.SYSTEM
+            and self._loaded_config_theme == UiTheme.DEFAULT
         ):
             is_dark_theme = self._detect_linux_dark_mode()
             if is_dark_theme:
-                # Apply a dark palette centrally defined
-                for key, value in DARK_PALETTE_COLORS.items():
-                    if isinstance(key, tuple):
-                        group, role = key
-                        palette.setColor(group, role, value)
-                    else:
-                        palette.setColor(key, value)
+                # Apply dark theme to palette using Qt's color scheme or manual fallback
+                apply_dark_theme_to_palette(palette)
                 self._dark_theme = True
                 self._accent_color = palette.color(QtGui.QPalette.ColorGroup.Active, QtGui.QPalette.ColorRole.Highlight)
             else:
@@ -264,12 +326,8 @@ def update_palette(self, palette, dark_theme, accent_color):
         # Adapt to Windows 10 color scheme (dark / light theme and accent color)
         super().update_palette(palette, dark_theme, accent_color)
         if dark_theme:
-            for key, value in DARK_PALETTE_COLORS.items():
-                if isinstance(key, tuple):
-                    group, role = key
-                    palette.setColor(group, role, value)
-                else:
-                    palette.setColor(key, value)
+            # Apply dark theme to palette using Qt's color scheme or manual fallback
+            apply_dark_theme_to_palette(palette)
 
 
 if IS_WIN:

test/test_config_upgrade.py

@@ -69,11 +69,13 @@
     upgrade_to_v3_0_0dev3,
     upgrade_to_v3_0_0dev4,
     upgrade_to_v3_0_0dev5,
+    upgrade_to_v3_0_0dev7,
 )
 from picard.const.defaults import (
     DEFAULT_FILE_NAMING_FORMAT,
     DEFAULT_REPLACEMENT,
     DEFAULT_SCRIPT_NAME,
+    DEFAULT_THEME_NAME,
 )
 from picard.util import unique_numbered_title
 from picard.version import Version
@@ -444,7 +446,7 @@ def test_upgrade_to_v2_6_0beta3(self):
         upgrade_to_v2_6_0beta3(self.config)
         self.assertNotIn('use_system_theme', self.config.setting)
         self.assertIn('ui_theme', self.config.setting)
-        self.assertEqual(str(UiTheme.SYSTEM), self.config.setting['ui_theme'])
+        self.assertEqual('system', self.config.setting['ui_theme'])
 
     def test_upgrade_to_v2_7_0dev3(self):
         # Legacy settings
@@ -561,3 +563,9 @@ def test_upgrade_to_v3_0_0dev5(self):
             self.config.setting['replace_dir_separator'] = os.altsep
             upgrade_to_v3_0_0dev5(self.config)
             self.assertEqual(DEFAULT_REPLACEMENT, self.config.setting['replace_dir_separator'])
+
+    def test_upgrade_to_v3_0_0dev7(self):
+        TextOption('setting', 'ui_theme', DEFAULT_THEME_NAME)
+        self.config.setting['ui_theme'] = 'system'
+        upgrade_to_v3_0_0dev7(self.config)
+        self.assertEqual(DEFAULT_THEME_NAME, self.config.setting['ui_theme'])

test/test_theme.py

@@ -446,12 +446,15 @@ def test_linux_dark_theme_palette(monkeypatch, already_dark_theme, dark_mode, ex
     monkeypatch.setattr(theme_mod, "IS_HAIKU", False)
     # Set config to SYSTEM
     config_mock = MagicMock()
-    config_mock.setting = {"ui_theme": "system"}
+    config_mock.setting = {"ui_theme": "default"}
     monkeypatch.setattr(theme_mod, "get_config", lambda: config_mock)
     # Patch _detect_linux_dark_mode to return dark_mode
     theme = theme_mod.BaseTheme()
     theme._detect_linux_dark_mode = lambda: dark_mode
 
+    # Mock QGuiApplication.styleHints() to return None to force manual fallback
+    monkeypatch.setattr(QtGui.QGuiApplication, "styleHints", lambda: None)
+
     # Mock app and palette
     app = DummyApp(already_dark_theme)
     theme.setup(app)
@@ -476,6 +479,10 @@ def test_linux_dark_theme_palette(monkeypatch, already_dark_theme, dark_mode, ex
 def test_windows_dark_theme_palette(monkeypatch, apps_use_light_theme, expected_dark):
     import picard.ui.theme as theme_mod
 
+    monkeypatch.setattr(theme_mod, "IS_WIN", True)
+    monkeypatch.setattr(theme_mod, "IS_MACOS", False)
+    monkeypatch.setattr(theme_mod, "IS_HAIKU", False)
+
     # Patch winreg
     winreg_mock = types.SimpleNamespace()
     monkeypatch.setattr(theme_mod, "winreg", winreg_mock)
@@ -511,7 +518,8 @@ def queryvalueex_side_effect(key, value):
     monkeypatch.setattr(theme_mod, "get_config", lambda: config_mock)
     # Instantiate WindowsTheme and run setup
     theme = theme_mod.WindowsTheme()
-
+    # Force manual fallback for palette changes
+    monkeypatch.setattr(QtGui.QGuiApplication, "styleHints", lambda: None)
     app = DummyApp()
     theme.setup(app)
     palette = app._palette
@@ -622,9 +630,10 @@ def test_linux_dark_palette_override_only_if_not_already_dark(
     monkeypatch.setattr(theme_mod, "IS_MACOS", False)
     monkeypatch.setattr(theme_mod, "IS_HAIKU", False)
     config_mock = MagicMock()
-    config_mock.setting = {"ui_theme": "system"}
+    config_mock.setting = {"ui_theme": "default"}
     monkeypatch.setattr(theme_mod, "get_config", lambda: config_mock)
-
+    # Force manual fallback for palette changes
+    monkeypatch.setattr(QtGui.QGuiApplication, "styleHints", lambda: None)
     app = DummyApp(already_dark_theme)
     theme = theme_mod.BaseTheme()
     theme._detect_linux_dark_mode = lambda: linux_dark_mode_detected