From 77e9b92c5a238444653492975c03872b52724c85 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Lukas=20Br=C3=BCbach?= <Bruebach.Lukas@bdosecurity.de>
Date: Sun, 1 Nov 2026 13:53:21 +0100
Subject: [PATCH] [Fonts] Restore the startup font when a config has no
 InterfaceDefault

- Capture the untouched application font next to the default palette and use
  it in previewFonts' else branch, so a config without InterfaceDefault
  restores the startup font instead of leaving the last preview applied.
- Drop the unpolish/polish loop from previewFonts: QApplication::setFont
  already notifies every widget, and the loop ran on every editor auto-apply.
---
 cockatrice/src/interface/theme_manager.cpp | 19 +++++++++----------
 cockatrice/src/interface/theme_manager.h   |  4 ++++
 2 files changed, 13 insertions(+), 10 deletions(-)

diff --git a/cockatrice/src/interface/theme_manager.cpp b/cockatrice/src/interface/theme_manager.cpp
index dc7e815a2..b23f15a2b 100644
--- a/cockatrice/src/interface/theme_manager.cpp
+++ b/cockatrice/src/interface/theme_manager.cpp
@@ -127,8 +127,10 @@ static QString usableDefaultStyle(const QString &style)
 ThemeManager::ThemeManager(QObject *parent) : QObject(parent)
 {
     defaultStyleName = usableDefaultStyle(qApp->style()->objectName());
-    // Capture the untouched application palette before any theme is applied.
+    // Capture the untouched application palette and font before any theme is
+    // applied.
     defaultPalette = qApp->palette();
+    defaultFont = qApp->font();
     ensureThemeDirectoryExists();
 #if (QT_VERSION >= QT_VERSION_CHECK(6, 5, 0))
     connect(QGuiApplication::styleHints(), &QStyleHints::colorSchemeChanged, this, [this] {
@@ -520,18 +522,15 @@ void ThemeManager::previewFonts(const FontConfig &cfg)
 {
     currentFonts = cfg;
 
+    // QApplication::setFont already sends a font change to every widget, so a
+    // repolish pass is not needed for fonts (unlike the palette path).
     const auto it = cfg.fonts.constFind(AppFont::InterfaceDefault);
     if (it != cfg.fonts.constEnd()) {
         qApp->setFont(it.value());
-
-        // Repolish every widget immediately so the preview applies without
-        // waiting for natural expose events, mirroring applyStyleAndPalette.
-        QStyle *style = qApp->style();
-        for (QWidget *widget : qApp->allWidgets()) {
-            style->unpolish(widget);
-            style->polish(widget);
-            widget->update();
-        }
+    } else {
+        // A config without InterfaceDefault means "no override": restore the
+        // startup font instead of leaving the last preview applied.
+        qApp->setFont(defaultFont);
     }
 
     emit fontsChanged();
diff --git a/cockatrice/src/interface/theme_manager.h b/cockatrice/src/interface/theme_manager.h
index d59212e92..c8fba2eb4 100644
--- a/cockatrice/src/interface/theme_manager.h
+++ b/cockatrice/src/interface/theme_manager.h
@@ -48,6 +48,10 @@ private:
     // palette is applied. Used as the base when a theme supplies no palette, so
     // switching away from a custom palette restores the original colours.
     QPalette defaultPalette;
+    // Pristine application font captured at startup, before any theme font is
+    // applied. Restored when a theme (or a preview) supplies no InterfaceDefault
+    // font, so switching away from a themed font cannot leave it behind.
+    QFont defaultFont;
     QString currentThemePath;
     std::array<QBrush, Role::MaxRole + 1> brushes;
     QStringMap availableThemes;