WIP: Allow configuring platform, e.g. for Windows 10 dark mode

settingsdialog/optioncategory.h

@@ -31,6 +31,7 @@ public:
     void setIcon(const QIcon &icon);
     const QList<OptionPage *> &pages() const;
     void assignPages(const QList<OptionPage *> &pages);
+    template<typename PageType> PageType *page();
     bool applyAllPages();
     void resetAllPages();
     bool matches(const QString &searchKeyWord) const;
@@ -89,6 +90,19 @@ inline const QList<OptionPage *> &OptionCategory::pages() const
     return m_pages;
 }
 
+/*!
+ * \brief Returns the first page with the specified \tp PageType or nullptr if there is no such page.
+ */
+template<typename PageType> PageType *OptionCategory::page()
+{
+    for (auto *const genericPage : m_pages) {
+        if (const auto *const page = qobject_cast<PageType *>(genericPage)) {
+            return page;
+        }
+    }
+    return nullptr;
+}
+
 /*!
  * \brief Returns the index of the currently shown page.
  * \remarks The returned index might be invalid/out of range.

settingsdialog/qtsettings.cpp

@@ -29,38 +29,35 @@ using namespace std;
 
 namespace QtUtilities {
 
+#if defined(Q_OS_WINDOWS) || defined(Q_OS_DARWIN)
+#define QT_UTILITIES_CAN_ENFORCE_FREETYPE 1
+#endif
+#if defined(Q_OS_WINDOWS)
+#define QT_UTILITIES_CAN_ENABLE_DARKMODE 1
+#endif
+
 struct QtSettingsData {
-    QtSettingsData();
+    QtSettingsData() = default;
 
     QFont font;
     QPalette palette;
     QString widgetStyle;
     QString styleSheetPath;
-    QString iconTheme;
+    QString iconTheme = QIcon::themeName();
     QLocale defaultLocale;
-    QString localeName;
+    QString localeName = defaultLocale.name();
     QString additionalPluginDirectory;
     QString additionalIconThemeSearchPath;
-    bool customFont;
+    QString fontEngine;
-    bool customPalette;
+    bool customFont = false;
-    bool customWidgetStyle;
+    bool customPalette = false;
-    bool customStyleSheet;
+    bool customWidgetStyle = false;
-    bool customIconTheme;
+    bool customStyleSheet = false;
-    bool customLocale;
+    bool customIconTheme = false;
+    bool customLocale = false;
+    bool enableDarkmode = false;
 };
 
-inline QtSettingsData::QtSettingsData()
-    : iconTheme(QIcon::themeName())
-    , localeName(defaultLocale.name())
-    , customFont(false)
-    , customPalette(false)
-    , customWidgetStyle(false)
-    , customStyleSheet(false)
-    , customIconTheme(false)
-    , customLocale(false)
-{
-}
-
 /*!
  * \brief Creates a new settings object.
  * \remarks Settings are not restored automatically. Instead, some values (font,
@@ -114,6 +111,8 @@ void QtSettings::restore(QSettings &settings)
     m_d->additionalPluginDirectory = settings.value(QStringLiteral("plugindir")).toString();
     m_d->additionalIconThemeSearchPath = settings.value(QStringLiteral("iconthemepath")).toString();
     TranslationFiles::additionalTranslationFilePath() = settings.value(QStringLiteral("trpath")).toString();
+    m_d->fontEngine = settings.value(QStringLiteral("fontengine")).toString();
+    m_d->enableDarkmode = settings.value(QStringLiteral("enabledarkmode")).toBool();
     settings.endGroup();
 }
 
@@ -138,17 +137,28 @@ void QtSettings::save(QSettings &settings) const
     settings.setValue(QStringLiteral("plugindir"), m_d->additionalPluginDirectory);
     settings.setValue(QStringLiteral("iconthemepath"), m_d->additionalIconThemeSearchPath);
     settings.setValue(QStringLiteral("trpath"), QVariant(TranslationFiles::additionalTranslationFilePath()));
+    settings.setValue(QStringLiteral("enforcefreetype"), m_d->fontEngine);
+    settings.setValue(QStringLiteral("enabledarkmode"), m_d->enableDarkmode);
     settings.endGroup();
 }
 
 /*!
- * \brief Applies the current configuration.
+ * \brief Applies values from the current configuration which need to be set before the platform plugin has been
+ *        instantiated.
+ */
+void QtSettings::applyPlatformSettings()
+{
+
+}
+
+/*!
+ * \brief Applies the current configuration except values which need to be set before the platform plugin has been
+ *        instantiated.
  * \remarks
  *  - Some settings take only affect after restarting the application.
  *  - QApplication/QGuiApplication must be instantiated before calling this
- * method.
+ *    method. Hence it makes most sense to call this directly after instantiating
- *  - Hence it makes most sense to call this directly after instantiating
+ *    QApplication/QGuiApplication.
- * QApplication/QGuiApplication.
  */
 void QtSettings::apply()
 {
@@ -205,8 +215,7 @@ void QtSettings::apply()
  * - The QtSettings instance does not keep the ownership over the returned
  * category.
  * - The pages of the returned category require the QtSetings instance which
- * hence
+ *   hence must be present until all pages are destroyed.
- *   must be present as long as all pages are destroyed.
  */
 OptionCategory *QtSettings::category()
 {

settingsdialog/qtsettings.h

@@ -15,8 +15,12 @@ struct QtSettingsData;
 
 BEGIN_DECLARE_UI_FILE_BASED_OPTION_PAGE_CUSTOM_CTOR(QtAppearanceOptionPage)
 public:
+enum PresetFlags { Dark };
 explicit QtAppearanceOptionPage(QtSettingsData &settings, QWidget *parentWidget = nullptr);
 
+Q_SIGNALS:
+void presetsApplied(PresetFlags flags);
+
 private:
 DECLARE_SETUP_WIDGETS
 QtSettingsData &m_settings;
@@ -47,6 +51,7 @@ public:
 
     void restore(QSettings &settings);
     void save(QSettings &settings) const;
+    void applyPlatformSettings();
     void apply();
     bool hasCustomFont() const;