DolphinQt/Settings: Add option to force the light or dark style on Windows.

Source/Core/DolphinQt/Settings.cpp

@@ -176,11 +176,12 @@ bool Settings::IsThemeDark()
 // Calling this before the main window has been created breaks the style of some widgets.
 void Settings::ApplyStyle()
 {
+  const StyleType style_type = GetStyleType();
   const QString stylesheet_name = GetUserStyleName();
   QString stylesheet_contents;
 
   // If we haven't found one, we continue with an empty (default) style
-  if (!stylesheet_name.isEmpty() && AreUserStylesEnabled())
+  if (!stylesheet_name.isEmpty() && style_type == StyleType::User)
   {
     // Load custom user stylesheet
     QDir directory = QDir(QString::fromStdString(File::GetUserPath(D_STYLES_IDX)));
@@ -197,7 +198,7 @@ void Settings::ApplyStyle()
     // which would select Qt's default theme, but unlike other OSes we don't automatically get a
     // default dark theme on Windows when the user has selected dark mode in the Windows settings.
     // So manually check if the user wants dark mode and, if yes, load our embedded dark theme.
-    if (IsSystemDark())
+    if (style_type == StyleType::Dark || (style_type != StyleType::Light && IsSystemDark()))
     {
       QFile file(QStringLiteral(":/dolphin_dark_win/dark.qss"));
       if (file.open(QFile::ReadOnly))
@@ -251,14 +252,30 @@ void Settings::ApplyStyle()
   qApp->setStyleSheet(stylesheet_contents);
 }
 
-bool Settings::AreUserStylesEnabled() const
+Settings::StyleType Settings::GetStyleType() const
 {
-  return GetQSettings().value(QStringLiteral("userstyle/enabled"), false).toBool();
+  if (GetQSettings().contains(QStringLiteral("userstyle/styletype")))
+  {
+    bool ok = false;
+    const int type_int = GetQSettings().value(QStringLiteral("userstyle/styletype")).toInt(&ok);
+    if (ok && type_int >= static_cast<int>(StyleType::MinValue) &&
+        type_int <= static_cast<int>(StyleType::MaxValue))
+    {
+      return static_cast<StyleType>(type_int);
+    }
   }
 
-void Settings::SetUserStylesEnabled(bool enabled)
+  // if the style type is unset or invalid, try the old enabled flag instead
+  const bool enabled = GetQSettings().value(QStringLiteral("userstyle/enabled"), false).toBool();
+  return enabled ? StyleType::User : StyleType::System;
+}
+
+void Settings::SetStyleType(StyleType type)
 {
-  GetQSettings().setValue(QStringLiteral("userstyle/enabled"), enabled);
+  GetQSettings().setValue(QStringLiteral("userstyle/styletype"), static_cast<int>(type));
+
+  // also set the old setting so that the config is correctly intepreted by older Dolphin builds
+  GetQSettings().setValue(QStringLiteral("userstyle/enabled"), type == StyleType::User);
 }
 
 void Settings::GetToolTipStyle(QColor& window_color, QColor& text_color,

Source/Core/DolphinQt/Settings.h

@@ -60,8 +60,20 @@ public:
 
   void SetUserStyleName(const QString& stylesheet_name);
   QString GetUserStyleName() const;
-  void SetUserStylesEnabled(bool enabled);
-  bool AreUserStylesEnabled() const;
+
+  enum class StyleType : int
+  {
+    System = 0,
+    Light = 1,
+    Dark = 2,
+    User = 3,
+
+    MinValue = 0,
+    MaxValue = 3,
+  };
+
+  void SetStyleType(StyleType type);
+  StyleType GetStyleType() const;
 
   // this evaluates the current stylesheet settings and refreshes the GUI with them
   void ApplyStyle();

Source/Core/DolphinQt/Settings/InterfacePane.cpp

@@ -260,7 +260,8 @@ void InterfacePane::LoadConfig()
   if (index > 0)
     SignalBlocking(m_combobox_userstyle)->setCurrentIndex(index);
 
-  SignalBlocking(m_checkbox_use_userstyle)->setChecked(Settings::Instance().AreUserStylesEnabled());
+  SignalBlocking(m_checkbox_use_userstyle)
+      ->setChecked(Settings::Instance().GetStyleType() == Settings::StyleType::User);
 
   const bool visible = m_checkbox_use_userstyle->isChecked();
 
@@ -297,7 +298,9 @@ void InterfacePane::OnSaveConfig()
   Config::SetBase(Config::MAIN_USE_BUILT_IN_TITLE_DATABASE,
                   m_checkbox_use_builtin_title_database->isChecked());
   Settings::Instance().SetDebugModeEnabled(m_checkbox_show_debugging_ui->isChecked());
-  Settings::Instance().SetUserStylesEnabled(m_checkbox_use_userstyle->isChecked());
+  Settings::Instance().SetStyleType(m_checkbox_use_userstyle->isChecked() ?
+                                        Settings::StyleType::User :
+                                        Settings::StyleType::System);
   Settings::Instance().SetUserStyleName(m_combobox_userstyle->currentData().toString());
   Settings::Instance().ApplyStyle();