1. class _DarkModeGenerator:
2.  
3.     """Get necessary blink settings to configure dark mode."""
4.  
5.     # Mapping from a colors.webpage.darkmode.algorithm setting value to
6.     # Chromium's DarkModeInversionAlgorithm enum values.
7.     _ALGORITHMS = {
8.         # 0: kOff (not exposed)
9.         # 1: kSimpleInvertForTesting (not exposed)
10.         'brightness-rgb': 2,  # kInvertBrightness
11.         'lightness-hsl': 3,  # kInvertLightness
12.         'lightness-cielab': 4,  # kInvertLightnessLAB
13.     }
14.  
15.     # Mapping from a colors.webpage.darkmode.policy.images setting value to
16.     # Chromium's DarkModeImagePolicy enum values.
17.     _IMAGE_POLICIES = {
18.         'always': 0,  # kFilterAll
19.         'never': 1,  # kFilterNone
20.         'smart': 2,  # kFilterSmart
21.     }
22.  
23.     # Mapping from a colors.webpage.darkmode.policy.page setting value to
24.     # Chromium's DarkModePagePolicy enum values.
25.     _PAGE_POLICIES = {
26.         'always': 0,  # kFilterAll
27.         'smart': 1,  # kFilterByBackground
28.     }
29.  
30.     def _val(self, key: str, value: str) -> typing.Tuple[str, str]:
31.         """Get a value tuple for the given dark mode setting."""
32.         # FIXME: This is "forceDarkMode" starting with Chromium 83
33.         prefix = 'darkMode'
34.         return (prefix + key, value)
35.  
36.     def _get(self, setting: str) -> typing.Any:
37.         """Get a darkmode setting from the config.
38.  
39.        To avoid blowing up the commandline length, we only pass modified
40.        settings to Chromium, as our defaults line up with Chromium's.
41.        """
42.         return config.instance.get('colors.webpage.darkmode.' + setting,
43.                                    fallback=False)
44.  
45.     def _is_set(self, value: typing.Any) -> bool:
46.         """Check whether the given value is set."""
47.         return not isinstance(value, usertypes.Unset)
48.  
49.     def generate(self) -> typing.Iterator[typing.Tuple[str, str]]:
50.         if not config.val.colors.webpage.darkmode.enabled:
51.             return
52.  
53.         if qtutils.version_check('5.15'):
54.             yield self._val('Enabled', 'true')
55.  
56.         algorithm = self._get('algorithm')
57.         contrast = self._get('contrast')
58.         policy_images = self._get('policy.images')
59.         policy_page = self._get('policy.page')
60.         treshold_text = self._get('threshold.text')
61.         treshold_background = self._get('threshold.background')
62.         grayscale_all = self._get('grayscale_all')
63.         grayscale_images = self._get('grayscale_images')
64.  
65.         if self._is_set(algorithm):
66.             key = ('InversionAlgorithm' if qtutils.version_check('5.15')
67.                    else '')
68.             value = self._ALGORITHMS[algorithm]
69.             yield self._val(key, value)
70.  
71.         if self._is_set(contrast):
72.             yield self._val('Contrast', str(contrast))
73.  
74.         if self._is_set(policy_images):
75.             value = self._IMAGE_POLICIES[policy_images]
76.             yield self._val('ImagePolicy', value)
77.  
78.         if self._is_set(policy_page):
79.             value = self._PAGE_POLICIES[policy_page]
80.             yield self._val('PagePolicy', value)
81.  
82.         # [ ... ]