Handle smart dark mode setting with Qt 5.15.0

Fixes #5505

1 files changed, 28 insertions, 13 deletions

diff --git a/qutebrowser/config/qtargs.py b/qutebrowser/config/qtargs.py
index a9d92e95d..46b54cf34 100644
--- a/qutebrowser/config/qtargs.py
+++ b/qutebrowser/config/qtargs.py
@@ -24,9 +24,15 @@ import sys
 import typing
 import argparse
 
+try:
+    from PyQt5.QtWebEngine import PYQT_WEBENGINE_VERSION
+except ImportError:
+    # Added in PyQt 5.13
+    PYQT_WEBENGINE_VERSION = None
+
 from qutebrowser.config import config
 from qutebrowser.misc import objects
-from qutebrowser.utils import usertypes, qtutils, utils
+from qutebrowser.utils import usertypes, qtutils, utils, log
 
 
 def qt_args(namespace: argparse.Namespace) -> typing.List[str]:
@@ -63,17 +69,11 @@ def qt_args(namespace: argparse.Namespace) -> typing.List[str]:
 
 def _darkmode_prefix() -> str:
     """Return the prefix to use for darkmode settings."""
-    try:
-        from PyQt5.QtWebEngine import PYQT_WEBENGINE_VERSION
-    except ImportError:
-        # Added in PyQt 5.13
+    if PYQT_WEBENGINE_VERSION is None or PYQT_WEBENGINE_VERSION < 0x050f02:
         return 'darkMode'
-
-    if PYQT_WEBENGINE_VERSION >= 0x050f02:
+    else:
         # QtWebEngine 5.15.2 comes with Chromium 83
         return 'forceDarkMode'
-    else:
-        return 'darkMode'
 
 
 def _darkmode_settings() -> typing.Iterator[typing.Tuple[str, str]]:
@@ -111,6 +111,14 @@ def _darkmode_settings() -> typing.Iterator[typing.Tuple[str, str]]:
         False: 'false',
     }
 
+    # Our defaults for policy.images are different from Chromium's, so we mark it as
+    # mandatory setting - except on Qt 5.15.0 where we don't, so we don't get the
+    # workaround warning below if the setting wasn't explicitly customized.
+    smart_image_policy_broken = PYQT_WEBENGINE_VERSION == 0x050f00
+    mandatory_settings = set()
+    if not smart_image_policy_broken:
+        mandatory_settings.add('policy.images')
+
     _setting_description_type = typing.Tuple[
         str,  # qutebrowser option name
         str,  # darkmode setting name
@@ -123,17 +131,17 @@ def _darkmode_settings() -> typing.Iterator[typing.Tuple[str, str]]:
             ('enabled', 'Enabled', bools),
             ('algorithm', 'InversionAlgorithm', algorithms),
         ]  # type: typing.List[_setting_description_type]
-        mandatory_setting = 'enabled'
+        mandatory_settings.add('enabled')
     else:
         settings = [
             ('algorithm', '', algorithms),
         ]
-        mandatory_setting = 'algorithm'
+        mandatory_settings.add('algorithm')
 
     settings += [
-        ('contrast', 'Contrast', None),
         ('policy.images', 'ImagePolicy', image_policies),
         ('policy.page', 'PagePolicy', page_policies),
+        ('contrast', 'Contrast', None),
         ('threshold.text', 'TextBrightnessThreshold', None),
         ('threshold.background', 'BackgroundBrightnessThreshold', None),
         ('grayscale.all', 'Grayscale', bools),
@@ -147,10 +155,17 @@ def _darkmode_settings() -> typing.Iterator[typing.Tuple[str, str]]:
         # actually turned on.
         value = config.instance.get(
             'colors.webpage.darkmode.' + setting,
-            fallback=setting == mandatory_setting)
+            fallback=setting in mandatory_settings)
         if isinstance(value, usertypes.Unset):
             continue
 
+        if setting == 'policy.images' and value == 'smart' and smart_image_policy_broken:
+            # WORKAROUND for
+            # https://codereview.qt-project.org/c/qt/qtwebengine-chromium/+/304211
+            log.init.warning("Ignoring colors.webpage.darkmode.policy.images = smart "
+                             "because of Qt 5.15.0 bug")
+            continue
+
         if mapping is not None:
             value = mapping[value]