fix: do not apply system theme on launch

Closes PrismLauncher/PrismLauncher#490

Regression introduced by PrismLauncher/PrismLauncher#249

Signed-off-by: Sefa Eyeoglu <contact@scrumplex.net>

launcher/Application.cpp

@@ -830,9 +830,7 @@ Application::Application(int &argc, char **argv) : QApplication(argc, argv)
         }
     });
 
-    {
-        applyCurrentlySelectedTheme();
-    }
+    applyCurrentlySelectedTheme(true);
 
     updateCapabilities();
 
@@ -1107,9 +1105,9 @@ QList<ITheme*> Application::getValidApplicationThemes()
     return m_themeManager->getValidApplicationThemes();
 }
 
-void Application::applyCurrentlySelectedTheme()
+void Application::applyCurrentlySelectedTheme(bool initial)
 {
-    m_themeManager->applyCurrentlySelectedTheme();
+    m_themeManager->applyCurrentlySelectedTheme(initial);
 }
 
 void Application::setApplicationTheme(const QString& name)

launcher/Application.h

@@ -120,7 +120,7 @@ public:
 
     void setIconTheme(const QString& name);
 
-    void applyCurrentlySelectedTheme();
+    void applyCurrentlySelectedTheme(bool initial = false);
 
     QList<ITheme*> getValidApplicationThemes();
 

launcher/ui/themes/ITheme.cpp

@@ -38,7 +38,7 @@
 #include <QDir>
 #include "Application.h"
 
-void ITheme::apply()
+void ITheme::apply(bool)
 {
     APPLICATION->setStyleSheet(QString());
     QApplication::setStyle(QStyleFactory::create(qtTheme()));

launcher/ui/themes/ITheme.h

@@ -41,7 +41,7 @@ class QStyle;
 class ITheme {
    public:
     virtual ~ITheme() {}
-    virtual void apply();
+    virtual void apply(bool initial);
     virtual QString id() = 0;
     virtual QString name() = 0;
     virtual bool hasStyleSheet() = 0;

launcher/ui/themes/SystemTheme.cpp

@@ -60,9 +60,13 @@ SystemTheme::SystemTheme()
     themeDebugLog() << "System theme not found, defaulted to Fusion";
 }
 
-void SystemTheme::apply()
+void SystemTheme::apply(bool initial)
 {
-    ITheme::apply();
+    // See https://github.com/MultiMC/Launcher/issues/1790
+    // or https://github.com/PrismLauncher/PrismLauncher/issues/490
+    if (initial)
+        return; 
+    ITheme::apply(initial);
 }
 
 QString SystemTheme::id()

launcher/ui/themes/SystemTheme.h

@@ -40,7 +40,7 @@ class SystemTheme : public ITheme {
    public:
     SystemTheme();
     virtual ~SystemTheme() {}
-    void apply() override;
+    void apply(bool initial) override;
 
     QString id() override;
     QString name() override;

launcher/ui/themes/ThemeManager.cpp

@@ -116,22 +116,22 @@ void ThemeManager::setIconTheme(const QString& name)
     QIcon::setThemeName(name);
 }
 
-void ThemeManager::applyCurrentlySelectedTheme()
+void ThemeManager::applyCurrentlySelectedTheme(bool initial)
 {
     setIconTheme(APPLICATION->settings()->get("IconTheme").toString());
     themeDebugLog() << "<> Icon theme set.";
-    setApplicationTheme(APPLICATION->settings()->get("ApplicationTheme").toString());
+    setApplicationTheme(APPLICATION->settings()->get("ApplicationTheme").toString(), initial);
     themeDebugLog() << "<> Application theme set.";
 }
 
-void ThemeManager::setApplicationTheme(const QString& name)
+void ThemeManager::setApplicationTheme(const QString& name, bool initial)
 {
     auto systemPalette = qApp->palette();
     auto themeIter = m_themes.find(name);
     if (themeIter != m_themes.end()) {
         auto& theme = themeIter->second;
         themeDebugLog() << "applying theme" << theme->name();
-        theme->apply();
+        theme->apply(initial);
     } else {
         themeWarningLog() << "Tried to set invalid theme:" << name;
     }

launcher/ui/themes/ThemeManager.h

@@ -37,8 +37,8 @@ class ThemeManager {
 
     QList<ITheme*> getValidApplicationThemes();
     void setIconTheme(const QString& name);
-    void applyCurrentlySelectedTheme();
-    void setApplicationTheme(const QString& name);
+    void applyCurrentlySelectedTheme(bool initial = false);
+    void setApplicationTheme(const QString& name, bool initial = false);
 
     /// <summary>
     /// Returns the cat based on selected cat and with events (Birthday, XMas, etc.)