turn top bar dark when night mode enabled on macOS

.bazelrc

@@ -5,6 +5,9 @@ common --experimental_repository_cache_hardlinks
 build:windows --action_env="PYTHON_SYS_EXECUTABLE=c:/python/python.exe"
 #build:linux --action_env="PYTHON_SYS_EXECUTABLE=/usr/local/bin/python3.8"
 
+# only affects the ankihelper library
+#build:macos --macos_cpus=x86_64,arm64
+
 # runfiles are off by default on Windows, and we need them
 build --enable_runfiles
 

qt/aqt/data/BUILD.bazel

@@ -1,6 +1,7 @@
 filegroup(
     name = "data",
     srcs = [
+        "//qt/aqt/data/lib",
         "//qt/aqt/data/web",
     ],
     visibility = ["//qt:__subpackages__"],

qt/aqt/data/lib/BUILD.bazel

@@ -0,0 +1,17 @@
+load("@bazel_skylib//rules:copy_file.bzl", "copy_file")
+
+copy_file(
+    name = "ankihelper_dylib",
+    src = "//qt/mac:helper_dylib",
+    out = "libankihelper.dylib",
+    tags = ["manual"],
+)
+
+filegroup(
+    name = "lib",
+    srcs = [] + select({
+        "//platforms:macos_x86_64": ["libankihelper.dylib"],
+        "//conditions:default": [],
+    }),
+    visibility = ["//qt:__subpackages__"],
+)

qt/aqt/platform.py

@@ -0,0 +1,28 @@
+# Copyright: Ankitects Pty Ltd and contributors
+# License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
+
+"""Platform-specific functionality."""
+
+import os
+from ctypes import CDLL
+
+import aqt.utils
+from anki.utils import isMac
+
+
+def set_dark_mode(enabled: bool) -> bool:
+    "True if setting successful."
+    if not isMac:
+        return False
+    try:
+        _set_dark_mode(enabled)
+        return True
+    except Exception as e:
+        # swallow exceptions, as library will fail on macOS 10.13
+        print(e)
+    return False
+
+
+def _set_dark_mode(enabled: bool) -> None:
+    path = os.path.join(aqt.utils.aqt_data_folder(), "lib", "libankihelper.dylib")
+    CDLL(path).set_darkmode_enabled(enabled)

qt/aqt/theme.py

@@ -8,6 +8,7 @@ from typing import Dict, Optional
 from anki.utils import isMac
 from aqt import QApplication, gui_hooks, isWin
 from aqt.colors import colors
+from aqt.platform import set_dark_mode
 from aqt.qt import QColor, QIcon, QPalette, QPixmap, QStyleFactory, Qt
 
 
@@ -16,15 +17,22 @@ class ThemeManager:
     _icon_cache_light: Dict[str, QIcon] = {}
     _icon_cache_dark: Dict[str, QIcon] = {}
     _icon_size = 128
+    _dark_mode_available: Optional[bool] = None
 
     def macos_dark_mode(self) -> bool:
         "True if the user has night mode on, and has forced native widgets."
         if not isMac:
             return False
 
+        if not self._night_mode_preference:
+            return False
+
+        if self._dark_mode_available is None:
+            self._dark_mode_available = set_dark_mode(True)
+
         from aqt import mw
 
-        return self._night_mode_preference and mw.pm.dark_mode_widgets()
+        return self._dark_mode_available and mw.pm.dark_mode_widgets()
 
     def get_night_mode(self) -> bool:
         return self._night_mode_preference

qt/mac/AnkiHelper.m

@@ -0,0 +1,16 @@
+// Copyright: Ankitects Pty Ltd and contributors
+// License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
+
+@import Foundation;
+@import AppKit;
+
+void set_darkmode_enabled(BOOL enabled) {
+    NSAppearance *appearance;
+    if (enabled) {
+        appearance = [NSAppearance appearanceNamed:NSAppearanceNameDarkAqua];
+    } else {
+        appearance = [NSAppearance appearanceNamed:NSAppearanceNameAqua];
+    }
+    
+    [NSApplication sharedApplication].appearance = appearance;
+}

qt/mac/BUILD.bazel

@@ -0,0 +1,19 @@
+load("@rules_cc//cc:defs.bzl", "objc_library")
+
+objc_library(
+    name = "helper_static",
+    srcs = ["AnkiHelper.m"],
+    enable_modules = True,
+    alwayslink = True,
+    sdk_frameworks = ["AppKit"],
+    tags = ["manual"],
+)
+
+apple_binary(
+    name = "helper_dylib",
+    binary_type = "dylib",
+    minimum_os_version = "10.14",
+    platform_type = "macos",
+    visibility = ["//qt:__subpackages__"],
+    deps = ["helper_static"],
+)

qt/mac/README.md

@@ -0,0 +1 @@
+Tiny helper library to set dark mode on and off on Macs.