From bc49e2f6274b3e625d7f1702a0762a6de387a695 Mon Sep 17 00:00:00 2001
From: Connor McLaughlin <stenzek@gmail.com>
Date: Sun, 24 Jul 2022 23:17:22 +1000
Subject: [PATCH] Qt: Don't reset theme when changing language

---
 src/duckstation-qt/mainwindow.cpp | 25 ++++++++++++++++++-------
 src/duckstation-qt/mainwindow.h   | 11 ++++++-----
 src/duckstation-qt/qthost.cpp     |  3 +++
 3 files changed, 27 insertions(+), 12 deletions(-)

diff --git a/src/duckstation-qt/mainwindow.cpp b/src/duckstation-qt/mainwindow.cpp
index 34a74c5d8..23ab64583 100644
--- a/src/duckstation-qt/mainwindow.cpp
+++ b/src/duckstation-qt/mainwindow.cpp
@@ -55,6 +55,8 @@ static constexpr char DISC_IMAGE_FILTER[] = QT_TRANSLATE_NOOP(
 static const char* DEFAULT_THEME_NAME = "darkfusion";
 
 MainWindow* g_main_window = nullptr;
+static QString s_unthemed_style_name;
+static bool s_unthemed_style_name_set;
 
 #if defined(_WIN32) || defined(__APPLE__)
 static const bool s_use_central_widget = false;
@@ -80,7 +82,7 @@ bool QtHost::IsSystemValid()
   return s_system_valid;
 }
 
-MainWindow::MainWindow() : QMainWindow(nullptr), m_unthemed_style_name(QApplication::style()->objectName())
+MainWindow::MainWindow() : QMainWindow(nullptr)
 {
   Assert(!g_main_window);
   g_main_window = this;
@@ -100,11 +102,20 @@ MainWindow::~MainWindow()
     g_main_window = nullptr;
 }
 
-void MainWindow::initialize()
+void MainWindow::updateApplicationTheme()
 {
+  if (!s_unthemed_style_name_set)
+  {
+    s_unthemed_style_name_set = true;
+    s_unthemed_style_name = QApplication::style()->objectName();
+  }
+
   setStyleFromSettings();
   setIconThemeFromSettings();
+}
 
+void MainWindow::initialize()
+{
   m_ui.setupUi(this);
   setupAdditionalUi();
   connectSignals();
@@ -1945,9 +1956,9 @@ void MainWindow::addThemeToMenu(const QString& name, const QString& key)
 void MainWindow::setTheme(const QString& theme)
 {
   Host::SetBaseStringSettingValue("UI", "Theme", theme.toUtf8().constData());
-  setStyleFromSettings();
-  setIconThemeFromSettings();
-  updateMenuSelectedTheme();
+  updateApplicationTheme();
+
+  // Sadly we need to recreate here, because otherwise the icon theme doesn't update.
   recreate();
 }
 
@@ -1957,7 +1968,7 @@ void MainWindow::setStyleFromSettings()
 
   if (theme == "qdarkstyle")
   {
-    qApp->setStyle(m_unthemed_style_name);
+    qApp->setStyle(s_unthemed_style_name);
     qApp->setPalette(QApplication::style()->standardPalette());
 
     QFile f(QStringLiteral(":qdarkstyle/style.qss"));
@@ -2047,7 +2058,7 @@ void MainWindow::setStyleFromSettings()
   {
     qApp->setPalette(QApplication::style()->standardPalette());
     qApp->setStyleSheet(QString());
-    qApp->setStyle(m_unthemed_style_name);
+    qApp->setStyle(s_unthemed_style_name);
   }
 }
 
diff --git a/src/duckstation-qt/mainwindow.h b/src/duckstation-qt/mainwindow.h
index 45dd9f452..1260dc2dd 100644
--- a/src/duckstation-qt/mainwindow.h
+++ b/src/duckstation-qt/mainwindow.h
@@ -65,6 +65,9 @@ public:
   explicit MainWindow();
   ~MainWindow();
 
+  /// Sets application theme according to settings.
+  static void updateApplicationTheme();
+
   /// Initializes the window. Call once at startup.
   void initialize();
 
@@ -166,9 +169,8 @@ protected:
   void dropEvent(QDropEvent* event) override;
 
 private:
-  void setTheme(const QString& theme);
-  void setStyleFromSettings();
-  void setIconThemeFromSettings();
+  static void setStyleFromSettings();
+  static void setIconThemeFromSettings();
   void setupAdditionalUi();
   void connectSignals();
   void addThemeToMenu(const QString& name, const QString& key);
@@ -212,6 +214,7 @@ private:
   void updateMenuSelectedTheme();
   std::string getDeviceDiscPath(const QString& title);
   void setGameListEntryCoverImage(const GameList::Entry* entry);
+  void setTheme(const QString& theme);
   void recreate();
 
   /// Fills menu with save state info and handlers.
@@ -233,8 +236,6 @@ private:
 
   Ui::MainWindow m_ui;
 
-  QString m_unthemed_style_name;
-
   GameListWidget* m_game_list_widget = nullptr;
 
   DisplayWidget* m_display_widget = nullptr;
diff --git a/src/duckstation-qt/qthost.cpp b/src/duckstation-qt/qthost.cpp
index 7511ae26e..2f8ff9477 100644
--- a/src/duckstation-qt/qthost.cpp
+++ b/src/duckstation-qt/qthost.cpp
@@ -2241,6 +2241,9 @@ int main(int argc, char* argv[])
   if (!QtHost::ParseCommandLineParametersAndInitializeConfig(app, autoboot))
     return EXIT_FAILURE;
 
+  // Set theme before creating any windows.
+  MainWindow::updateApplicationTheme();
+
   // Start up the CPU thread.
   MainWindow* main_window = new MainWindow();
   QtHost::HookSignals();