Qt: Add theme selection and dark theme

src/duckstation-qt/CMakeLists.txt

@@ -3,7 +3,7 @@ set(CMAKE_AUTORCC ON)
 set(CMAKE_AUTOUIC ON)
 
 add_executable(duckstation-qt
-  resources/icons.qrc
+  resources/resources.qrc
   aboutdialog.cpp
   aboutdialog.h
   advancedsettingswidget.cpp

src/duckstation-qt/duckstation-qt.vcxproj

@@ -148,7 +148,7 @@
     </QtUi>
   </ItemGroup>
   <ItemGroup>
-    <QtResource Include="resources\icons.qrc">
+    <QtResource Include="resources\resources.qrc">
       <FileType>Document</FileType>
     </QtResource>
   </ItemGroup>
@@ -171,7 +171,7 @@
     <ClCompile Include="$(IntDir)moc_qthostinterface.cpp" />
     <ClCompile Include="$(IntDir)moc_qtprogresscallback.cpp" />
     <ClCompile Include="$(IntDir)moc_settingsdialog.cpp" />
-    <ClCompile Include="$(IntDir)qrc_icons.cpp" />
+    <ClCompile Include="$(IntDir)qrc_resources.cpp" />
   </ItemGroup>
   <ItemGroup>
     <Natvis Include="qt5.natvis" />

src/duckstation-qt/mainwindow.cpp

@@ -16,6 +16,7 @@
 #include "settingsdialog.h"
 #include "settingwidgetbinder.h"
 #include <QtCore/QDebug>
+#include <QtCore/QFile>
 #include <QtCore/QFileInfo>
 #include <QtCore/QUrl>
 #include <QtGui/QCursor>
@@ -40,6 +41,7 @@ MainWindow::MainWindow(QtHostInterface* host_interface) : QMainWindow(nullptr),
   m_ui.setupUi(this);
   setupAdditionalUi();
   connectSignals();
+  updateTheme();
 
   resize(800, 700);
 }
@@ -603,6 +605,52 @@ void MainWindow::connectSignals()
   SettingWidgetBinder::BindWidgetToBoolSetting(m_host_interface, m_ui.actionDebugShowTimersState,
                                                "Debug/ShowTimersState");
   SettingWidgetBinder::BindWidgetToBoolSetting(m_host_interface, m_ui.actionDebugShowMDECState, "Debug/ShowMDECState");
+
+  addThemeToMenu(tr("Default"), QStringLiteral("default"));
+  addThemeToMenu(tr("Dark"), QStringLiteral("qdarkstyle"));
+}
+
+void MainWindow::addThemeToMenu(const QString& name, const QString& key)
+{
+  QAction* action = m_ui.menuSettingsTheme->addAction(name);
+  action->setCheckable(true);
+  action->setData(key);
+  connect(action, &QAction::toggled, [this, key](bool) { setTheme(key); });
+}
+
+void MainWindow::setTheme(const QString& theme)
+{
+  m_host_interface->putSettingValue(QStringLiteral("UI/Theme"), theme);
+  updateTheme();
+}
+
+void MainWindow::updateTheme()
+{
+  QString theme = m_host_interface->getSettingValue(QStringLiteral("UI/Theme"), QStringLiteral("default")).toString();
+  if (theme == QStringLiteral("qdarkstyle"))
+  {
+    QFile f(QStringLiteral(":qdarkstyle/style.qss"));
+    if (f.open(QFile::ReadOnly | QFile::Text))
+      qApp->setStyleSheet(f.readAll());
+  }
+  else
+  {
+    qApp->setStyleSheet(QString());
+  }
+
+  for (QObject* obj : m_ui.menuSettingsTheme->children())
+  {
+    QAction* action = qobject_cast<QAction*>(obj);
+    if (action)
+    {
+      QVariant action_data(action->data());
+      if (action_data.isValid())
+      {
+        QSignalBlocker blocker(action);
+        action->setChecked(action_data == theme);
+      }
+    }
+  }
 }
 
 SettingsDialog* MainWindow::getSettingsDialog()

src/duckstation-qt/mainwindow.h

@@ -35,6 +35,9 @@ private Q_SLOTS:
   void destroyDisplay();
   void focusDisplayWidget();
 
+  void setTheme(const QString& theme);
+  void updateTheme();
+
   void onEmulationStarting();
   void onEmulationStarted();
   void onEmulationStopped();
@@ -65,6 +68,7 @@ protected:
 private:
   void setupAdditionalUi();
   void connectSignals();
+  void addThemeToMenu(const QString& name, const QString& key);
   void updateEmulationActions(bool starting, bool running);
   void switchToGameListView();
   void switchToEmulationView();

src/duckstation-qt/mainwindow.ui

@@ -85,6 +85,11 @@
     <property name="title">
      <string>S&amp;ettings</string>
     </property>
+    <widget class="QMenu" name="menuSettingsTheme">
+     <property name="title">
+      <string>Theme</string>
+     </property>
+    </widget>
     <addaction name="actionFullscreen"/>
     <addaction name="separator"/>
     <addaction name="actionGeneralSettings"/>
@@ -101,6 +106,7 @@
     <addaction name="actionScanForNewGames"/>
     <addaction name="actionRescanAllGames"/>
     <addaction name="separator"/>
+    <addaction name="menuSettingsTheme"/>
    </widget>
    <widget class="QMenu" name="menuHelp">
     <property name="title">