Add function to determine whether palette is dark

misc/desktoputils.cpp

@@ -38,4 +38,14 @@ bool openLocalFileOrDir(const QString &path)
 #endif
     return QDesktopServices::openUrl(url);
 }
+
+/*!
+ * \brief Returns whether \a palette is dark.
+ * \remarks Just call with no argument to check for the default palette to see whether "dark mode" is enabled.
+ */
+bool isPaletteDark(const QPalette &palette)
+{
+    return palette.color(QPalette::WindowText).lightness() > palette.color(QPalette::Window).lightness();
+}
+
 } // namespace QtUtilities

misc/desktoputils.h

@@ -3,13 +3,15 @@
 
 #include "../global.h"
 
-#include <QtGlobal>
+#include <QPalette>
 
 QT_FORWARD_DECLARE_CLASS(QString)
 
 namespace QtUtilities {
 
 QT_UTILITIES_EXPORT bool openLocalFileOrDir(const QString &path);
-}
+QT_UTILITIES_EXPORT bool isPaletteDark(const QPalette &palette = QPalette());
+
+} // namespace QtUtilities
 
 #endif // DESKTOP_UTILS_DESKTOPSERVICES_H