launcher: add System/Dark/Light theme option

src/launcher/CMakeLists.txt

@@ -1,5 +1,5 @@
 
-find_package(Qt6 COMPONENTS Concurrent Network Widgets REQUIRED)
+find_package(Qt6 6.8 COMPONENTS Concurrent Network Widgets REQUIRED)
 add_subdirectory("${KYTY_SOURCE_DIR}/updater" "${CMAKE_CURRENT_BINARY_DIR}/updater")
 
 set(CMAKE_AUTOUIC_SEARCH_PATHS forms)

src/launcher/forms/main_dialog.ui

@@ -112,6 +112,49 @@
          </property>
         </widget>
        </item>
+       <item>
+        <layout class="QHBoxLayout" name="themeLayout">
+         <item>
+          <widget class="QLabel" name="label_theme">
+           <property name="text">
+            <string>Theme:</string>
+           </property>
+          </widget>
+         </item>
+         <item>
+          <widget class="QComboBox" name="theme_combo">
+           <item>
+            <property name="text">
+             <string>System</string>
+            </property>
+           </item>
+           <item>
+            <property name="text">
+             <string>Dark</string>
+            </property>
+           </item>
+           <item>
+            <property name="text">
+             <string>Light</string>
+            </property>
+           </item>
+          </widget>
+         </item>
+         <item>
+          <spacer name="themeSpacer">
+           <property name="orientation">
+            <enum>Qt::Horizontal</enum>
+           </property>
+           <property name="sizeHint" stdset="0">
+            <size>
+             <width>40</width>
+             <height>20</height>
+            </size>
+           </property>
+          </spacer>
+         </item>
+        </layout>
+       </item>
       </layout>
      </item>
     </layout>

src/launcher/src/mainDialog.cpp

@@ -12,6 +12,7 @@
 #include <QApplication>
 #include <QByteArray>
 #include <QCheckBox>
+#include <QComboBox>
 #include <QDialog>
 #include <QDir>
 #include <QFile>
@@ -26,6 +27,7 @@
 #include <QRegularExpression>
 #include <QSettings>
 #include <QStringList>
+#include <QStyleHints>
 #include <QTextStream>
 #include <QVariant>
 #include <QtCore>
@@ -62,6 +64,7 @@ constexpr DWORD CMD_Y_CHARS = 1000;
 constexpr char SETTINGS_MAIN_DIALOG[]        = "MainDialog";
 constexpr char SETTINGS_MAIN_LAST_GEOMETRY[] = "geometry";
 constexpr char SETTINGS_CHECK_UPDATES[]      = "check_updates_on_startup";
+constexpr char SETTINGS_THEME[]              = "theme";
 
 class MainDialogPrivate: public QObject {
 	Q_OBJECT
@@ -86,6 +89,17 @@ public:
 private:
 	static QByteArray g_last_geometry;
 	static bool       g_check_updates_on_startup;
+	static int        g_theme;
+
+	static void ApplyTheme(int theme) {
+		auto scheme = Qt::ColorScheme::Unknown;
+		switch (theme) {
+			case 1: scheme = Qt::ColorScheme::Dark; break;
+			case 2: scheme = Qt::ColorScheme::Light; break;
+			default: break;
+		}
+		QApplication::styleHints()->setColorScheme(scheme);
+	}
 
 	Ui::MainDialog* m_ui             = {nullptr};
 	MainDialog*     m_main_dialog    = nullptr;
@@ -101,6 +115,7 @@ private:
 
 QByteArray MainDialogPrivate::g_last_geometry;
 bool       MainDialogPrivate::g_check_updates_on_startup = true;
+int        MainDialogPrivate::g_theme                    = 0;
 
 MainDialog::MainDialog(QWidget* parent): QDialog(parent), m_p(new MainDialogPrivate(this)) {
 	m_p->Setup(this);
@@ -119,6 +134,8 @@ void MainDialogPrivate::Setup(MainDialog* main_dialog) {
 	m_main_dialog = main_dialog;
 	m_update_checker = new UpdateChecker(main_dialog);
 	m_ui->check_updates_on_startup->setChecked(g_check_updates_on_startup);
+	m_ui->theme_combo->setCurrentIndex(g_theme);
+	ApplyTheme(g_theme);
 	m_ui->check_updates_link->setVisible(UpdateChecker::IsSupported());
 	m_ui->check_updates_on_startup->setVisible(UpdateChecker::IsSupported());
 
@@ -149,6 +166,11 @@ void MainDialogPrivate::Setup(MainDialog* main_dialog) {
 		g_check_updates_on_startup = checked;
 		m_ui->widget->WriteSettings();
 	});
+	connect(m_ui->theme_combo, &QComboBox::currentIndexChanged, this, [this](int index) {
+		g_theme = index;
+		ApplyTheme(index);
+		m_ui->widget->WriteSettings();
+	});
 	connect(main_dialog, &MainDialog::Resize, [this]() {
 		g_last_geometry = m_main_dialog->saveGeometry();
 		m_ui->widget->WriteSettings();
@@ -516,6 +538,7 @@ void MainDialogPrivate::WriteSettings(QSettings& s) {
 		s.setValue(SETTINGS_MAIN_LAST_GEOMETRY, g_last_geometry);
 	}
 	s.setValue(SETTINGS_CHECK_UPDATES, g_check_updates_on_startup);
+	s.setValue(SETTINGS_THEME, g_theme);
 
 	s.endGroup();
 }
@@ -525,6 +548,10 @@ void MainDialogPrivate::ReadSettings(QSettings& s) {
 
 	g_last_geometry = s.value(SETTINGS_MAIN_LAST_GEOMETRY, g_last_geometry).toByteArray();
 	g_check_updates_on_startup = s.value(SETTINGS_CHECK_UPDATES, true).toBool();
+	g_theme                    = s.value(SETTINGS_THEME, 0).toInt();
+	if (g_theme < 0 || g_theme > 2) {
+		g_theme = 0;
+	}
 
 	s.endGroup();
 }