Add an option to let the user choose the qt style used by the app (#2663

)

* Remove hardcoded usage of Fusion style on Gtk; add an option to use a custom Qt Style (like Fusion on Windows, supporting dark mode)

* Update src/modules/options/OptionsWidget_theme.cpp

Co-authored-by: Alexey Sokolov <alexey+github@asokolov.org>

src/kvirc/kernel/KviApplication.cpp

@@ -228,16 +228,6 @@ KviApplication::KviApplication(int & argc, char ** argv)
 	// don't let qt quit the application by itself
 	setQuitOnLastWindowClosed(false);
 
-//note: the early qApp->style() call leads to a crash on osx
-#if !defined(COMPILE_ENABLE_GTKSTYLE) && !defined(COMPILE_ON_MAC)
-	// workaround for gtk+ style forcing a crappy white background (ticket #777, #964, #1009, ..)
-	if(QString("QGtkStyle").compare(qApp->style()->metaObject()->className()) == 0)
-	{
-		setStyle(QStyleFactory::create("Fusion"));
-		setPalette(style()->standardPalette());
-	}
-#endif
-
 	// Restore Qt5-like rounding to fix HiDPI support on QWebEngine
 	QGuiApplication::setHighDpiScaleFactorRoundingPolicy(Qt::HighDpiScaleFactorRoundingPolicy::Round);
 }
@@ -343,6 +333,16 @@ void KviApplication::setup()
 	updatePseudoTransparency();
 #endif
 
+	{
+		// set global Qt style if needed
+		QString requestedQtStyle = KVI_OPTION_STRING(KviOption_stringQtStyle);
+
+		if(!requestedQtStyle.isEmpty() && QStyleFactory::keys().contains(requestedQtStyle)) {
+			setStyle(QStyleFactory::create(requestedQtStyle));
+			setPalette(style()->standardPalette());
+		}
+	}
+
 	// enforce our "icon in popups" option - this is done also in each updateGui() call
 	setAttribute(Qt::AA_DontShowIconsInMenus, !KVI_OPTION_BOOL(KviOption_boolShowIconsInPopupMenus));
 

src/kvirc/kernel/KviOptions.cpp

@@ -412,7 +412,8 @@ KviStringOption g_stringOptionsTable[KVI_NUM_STRING_OPTIONS] = {
 	STRING_OPTION("DefaultSrvEncoding", "", KviOption_sectFlagFrame),
 	STRING_OPTION("LogsPath", "", KviOption_sectFlagUser | KviOption_encodePath),
 	STRING_OPTION("LogsDynamicPath", "", KviOption_sectFlagUser | KviOption_encodePath),
-	STRING_OPTION("LogsExportPath", "", KviOption_sectFlagUser | KviOption_encodePath)
+	STRING_OPTION("LogsExportPath", "", KviOption_sectFlagUser | KviOption_encodePath),
+	STRING_OPTION("QtStyle", "", KviOption_sectFlagIrcView | KviOption_resetUpdateGui | KviOption_groupTheme | KviOption_resetReloadImages)
 };
 
 #define STRINGLIST_OPTION(_txt, _flags) \

src/kvirc/kernel/KviOptions.h

@@ -423,8 +423,9 @@ DECLARE_OPTION_STRUCT(KviStringListOption, QStringList)
 #define KviOption_stringLogsPath 57                                            /* logfolder */
 #define KviOption_stringLogsDynamicPath 58                                     /* logfolder */
 #define KviOption_stringLogsExportPath 59                                      /* logview module log export */
+#define KviOption_stringQtStyle 60                                             /* themes::general */
 
-#define KVI_NUM_STRING_OPTIONS 60
+#define KVI_NUM_STRING_OPTIONS 61
 
 #define KVI_STRINGLIST_OPTIONS_PREFIX "stringlist"
 #define KVI_STRINGLIST_OPTIONS_PREFIX_LEN 10

src/modules/options/OptionsWidget_theme.cpp

@@ -31,7 +31,9 @@
 #include "KviTalToolTip.h"
 
 #include <QLayout>
+#include <QStyleFactory>
 
+#define DEFAULT_QT_STYLE "Default"
 OptionsWidget_theme::OptionsWidget_theme(QWidget * parent)
     : KviOptionsWidget(parent)
 {
@@ -44,12 +46,38 @@ OptionsWidget_theme::OptionsWidget_theme(QWidget * parent)
 	    KVI_OPTION_BOOL(KviOption_boolUseGlobalApplicationFont));
 	connect(b, SIGNAL(toggled(bool)), f, SLOT(setEnabled(bool)));
 
-	addRowSpacer(0, 3, 1, 3);
+	addLabel(0, 3, 0, 3, __tr2qs_ctx("Qt Style:", "options"));
+	m_pQtStyle = new QComboBox(this);
+	addWidgetToLayout(m_pQtStyle, 1, 3, 1, 3);
+	m_pQtStyle->addItem(DEFAULT_QT_STYLE);
+	for (const QString& key : QStyleFactory::keys()) {
+		m_pQtStyle->addItem(key);
+	}
+	if(KVI_OPTION_STRING(KviOption_stringQtStyle).isEmpty()) {
+		m_pQtStyle->setCurrentText(DEFAULT_QT_STYLE);
+	} else {
+		m_pQtStyle->setCurrentText(KVI_OPTION_STRING(KviOption_stringQtStyle));
+	}
+
+	addRowSpacer(0, 4, 1, 4);
 }
 
 OptionsWidget_theme::~OptionsWidget_theme()
     = default;
 
+void OptionsWidget_theme::commit()
+{
+	KviOptionsWidget::commit();
+
+	if(m_pQtStyle->currentText() == DEFAULT_QT_STYLE) {
+		KVI_OPTION_STRING(KviOption_stringQtStyle) = "";
+	} else {
+		KVI_OPTION_STRING(KviOption_stringQtStyle) = m_pQtStyle->currentText();
+		QApplication::setStyle(QStyleFactory::create(KVI_OPTION_STRING(KviOption_stringQtStyle)));
+		QApplication::setPalette(style()->standardPalette());
+	}
+}
+
 OptionsWidget_themeTransparency::OptionsWidget_themeTransparency(QWidget * parent)
     : KviOptionsWidget(parent)
 {

src/modules/options/OptionsWidget_theme.h

@@ -28,6 +28,8 @@
 #include "KviOptionsWidget.h"
 #include "KviSelectors.h"
 
+#include <QComboBox>
+
 #define KVI_OPTIONS_WIDGET_ICON_OptionsWidget_theme KviIconManager::Gui
 #define KVI_OPTIONS_WIDGET_NAME_OptionsWidget_theme __tr2qs_no_lookup("General")
 #define KVI_OPTIONS_WIDGET_KEYWORDS_OptionsWidget_theme __tr2qs_no_lookup("theme")
@@ -39,6 +41,12 @@ class OptionsWidget_theme : public KviOptionsWidget
 public:
 	OptionsWidget_theme(QWidget * parent);
 	~OptionsWidget_theme();
+
+protected:
+	void commit() override;
+
+private:
+	QComboBox * m_pQtStyle;
 };
 
 #define KVI_OPTIONS_WIDGET_ICON_OptionsWidget_themeTransparency KviIconManager::Transparent