Implement ui style selection dialog 12832

lib/RELEASE-NOTES

@@ -53,6 +53,10 @@
 
 * Edit > Paste operation now preserves newlines in text by default.
 
+* Dark mode on Windows is possible now by choosing "fusion" user interface style
+  in user interface preferences dialog, your system style has to be set to dark
+  (bug 12832).
+
 
 !!Documents compilation process and images conversion
 

src/LyX.cpp

@@ -354,6 +354,12 @@ int LyX::exec(int & argc, char * argv[])
 		return app.exec();
 	}
 
+	// This one is edited through the preferences dialog.
+	// need to call this before createApplication
+	// because we need to know the Qt style for creating the Application
+	if (!readRcFile("preferences", true))
+		return EXIT_FAILURE;
+
 	// Let the frontend parse and remove all arguments that it knows
 	pimpl_->application_.reset(createApplication(argc, argv));
 
@@ -994,10 +1000,6 @@ bool LyX::init()
 	pimpl_->system_movers_ = pimpl_->movers_;
 	system_lcolor = lcolor;
 
-	// This one is edited through the preferences dialog.
-	if (!readRcFile("preferences", true))
-		return false;
-
 	// The language may have been set to someting useful through prefs
 	setLocale();
 

src/LyXRC.cpp

@@ -197,6 +197,7 @@ LexerKeyword lyxrcTags[] = {
 	{ "\\texinputs_prefix", LyXRC::RC_TEXINPUTS_PREFIX },
 	{ "\\thesaurusdir_path", LyXRC::RC_THESAURUSDIRPATH },
 	{ "\\ui_file", LyXRC::RC_UIFILE },
+	{ "\\ui_style", LyXRC::RC_UI_STYLE },
 	{ "\\use_converter_cache", LyXRC::RC_USE_CONVERTER_CACHE },
 	{ "\\use_converter_needauth", LyXRC::RC_USE_CONVERTER_NEEDAUTH },
 	{ "\\use_converter_needauth_forbidden", LyXRC::RC_USE_CONVERTER_NEEDAUTH_FORBIDDEN },
@@ -603,6 +604,10 @@ LyXRC::ReturnValues LyXRC::read(Lexer & lexrc, bool check_format)
 			lexrc >> icon_set;
 			break;
 
+		case RC_UI_STYLE:
+			lexrc >> ui_style;
+			break;
+
 		case RC_USE_SYSTEM_THEME_ICONS:
 			lexrc >> use_system_theme_icons;
 			break;
@@ -1624,6 +1629,15 @@ void LyXRC::write(ostream & os, bool ignore_system_lyxrc, string const & name) c
 		if (tag != RC_LAST)
 			break;
 		// fall through
+	case RC_UI_STYLE:
+		if (ignore_system_lyxrc ||
+			ui_style != system_lyxrc.ui_style) {
+			os << "\\ui_style \"" << ui_style
+				<< "\"\n";
+		}
+		if (tag != RC_LAST)
+			break;
+		// fall through
 	case RC_USE_SYSTEM_THEME_ICONS:
 		if (ignore_system_lyxrc ||
 			  use_system_theme_icons != system_lyxrc.use_system_theme_icons) {
@@ -2950,6 +2964,7 @@ void actOnUpdatedPrefs(LyXRC const & lyxrc_orig, LyXRC const & lyxrc_new)
 	case LyXRC::RC_GROUP_LAYOUTS:
 	case LyXRC::RC_HUNSPELLDIR_PATH:
 	case LyXRC::RC_ICON_SET:
+	case LyXRC::RC_UI_STYLE:
 	case LyXRC::RC_INDEX_ALTERNATIVES:
 	case LyXRC::RC_INDEX_COMMAND:
 	case LyXRC::RC_JBIBTEX_COMMAND:

src/LyXRC.h

@@ -173,6 +173,7 @@ public:
 		RC_TEXINPUTS_PREFIX,
 		RC_THESAURUSDIRPATH,
 		RC_UIFILE,
+		RC_UI_STYLE,
 		RC_USELASTFILEPOS,
 		RC_USER_EMAIL,
 		RC_USER_INITIALS,
@@ -473,6 +474,8 @@ public:
 	std::string user_initials;
 	/// icon set name
 	std::string icon_set;
+	/// ui style name
+	std::string ui_style;
 	/// whether to use the icons from the theme
 	bool use_system_theme_icons = false;
 	/// True if the TeX engine cannot handle posix paths

src/frontends/qt/GuiApplication.cpp

@@ -222,6 +222,9 @@ frontend::Application * createApplication(int & argc, char * argv[])
 #endif
 #endif
 
+	if (!lyxrc.ui_style.empty())
+		frontend::GuiApplication::setStyle(toqstr(lyxrc.ui_style));
+
 	frontend::GuiApplication * guiApp = new frontend::GuiApplication(argc, argv);
 	// I'd rather do that in the constructor, but I do not think that
 	// the palette is accessible there.

src/frontends/qt/GuiPrefs.cpp

@@ -63,6 +63,7 @@
 #include <QPushButton>
 #include <QSpinBox>
 #include <QString>
+#include <QStyleFactory>
 #include <QTreeWidget>
 #include <QTreeWidgetItem>
 #include <QValidator>
@@ -2494,6 +2495,8 @@ PrefUserInterface::PrefUserInterface(GuiPreferences * form)
 		this, SIGNAL(changed()));
 	connect(iconSetCO, SIGNAL(activated(int)),
 		this, SIGNAL(changed()));
+	connect(uiStyleCO, SIGNAL(activated(int)),
+		this, SIGNAL(changed()));
 	connect(useSystemThemeIconsCB, SIGNAL(clicked()),
 		this, SIGNAL(changed()));
 	connect(lastfilesSB, SIGNAL(valueChanged(int)),
@@ -2516,6 +2519,11 @@ PrefUserInterface::PrefUserInterface(GuiPreferences * form)
 	iconSetCO->addItem(qt_("Classic"), "classic");
 	iconSetCO->addItem(qt_("Oxygen"), "oxygen");
 
+	for (const auto& style : QStyleFactory::keys())
+	{
+		uiStyleCO->addItem(style.toLower());
+	}
+
 	if (guiApp->platformName() != "xcb"
 	    && !guiApp->platformName().contains("wayland"))
 		useSystemThemeIconsCB->hide();
@@ -2527,6 +2535,9 @@ void PrefUserInterface::applyRC(LyXRC & rc) const
 	rc.icon_set = fromqstr(iconSetCO->itemData(
 		iconSetCO->currentIndex()).toString());
 
+	frontend::GuiApplication::setStyle(uiStyleCO->currentText());
+	rc.ui_style = fromqstr(uiStyleCO->currentText());
+
 	rc.ui_file = internal_path(fromqstr(uiFileED->text()));
 	rc.use_system_theme_icons = useSystemThemeIconsCB->isChecked();
 	rc.num_lastfiles = lastfilesSB->value();
@@ -2545,6 +2556,8 @@ void PrefUserInterface::updateRC(LyXRC const & rc)
 	if (iconset < 0)
 		iconset = 0;
 	iconSetCO->setCurrentIndex(iconset);
+	uiStyleCO->setCurrentIndex(uiStyleCO->findText(
+		frontend::GuiApplication::style()->objectName().toLower()));
 	useSystemThemeIconsCB->setChecked(rc.use_system_theme_icons);
 	uiFileED->setText(toqstr(external_path(rc.ui_file)));
 	lastfilesSB->setValue(rc.num_lastfiles);

src/frontends/qt/ui/PrefUi.ui

@@ -7,7 +7,7 @@
     <x>0</x>
     <y>0</y>
     <width>556</width>
-    <height>476</height>
+    <height>502</height>
    </rect>
   </property>
   <property name="sizePolicy">
@@ -42,18 +42,8 @@
       </item>
       <item row="0" column="0">
        <layout class="QGridLayout" name="gridLayout" columnstretch="0,1,0">
-        <item row="0" column="0">
+        <item row="1" column="2">
-         <widget class="QLabel" name="uiFileLA">
+         <layout class="QHBoxLayout" name="horizontalLayout"/>
-          <property name="text">
-           <string>&amp;User interface file:</string>
-          </property>
-          <property name="buddy">
-           <cstring>uiFileED</cstring>
-          </property>
-         </widget>
-        </item>
-        <item row="0" column="1">
-         <widget class="QLineEdit" name="uiFileED"/>
         </item>
         <item row="0" column="2">
          <widget class="QPushButton" name="uiFilePB">
@@ -62,6 +52,13 @@
           </property>
          </widget>
         </item>
+        <item row="1" column="1">
+         <widget class="QComboBox" name="iconSetCO">
+          <property name="toolTip">
+           <string>The icon set to use. Warning: normal size of icons may be wrong until you save the preferences and restart LyX.</string>
+          </property>
+         </widget>
+        </item>
         <item row="1" column="0">
          <widget class="QLabel" name="iconSetLA">
           <property name="text">
@@ -72,15 +69,38 @@
           </property>
          </widget>
         </item>
-        <item row="1" column="1">
+        <item row="0" column="0">
-         <widget class="QComboBox" name="iconSetCO">
+         <widget class="QLabel" name="uiFileLA">
-          <property name="toolTip">
+          <property name="text">
-           <string>The icon set to use. Warning: normal size of icons may be wrong until you save the preferences and restart LyX.</string>
+           <string>&amp;User interface file:</string>
+          </property>
+          <property name="buddy">
+           <cstring>uiFileED</cstring>
           </property>
          </widget>
         </item>
-        <item row="1" column="2">
+        <item row="0" column="1">
-         <layout class="QHBoxLayout" name="horizontalLayout"/>
+         <widget class="QLineEdit" name="uiFileED"/>
+        </item>
+        <item row="2" column="0">
+         <widget class="QLabel" name="uiStyleLA">
+          <property name="text">
+           <string>User interface &amp;style:</string>
+          </property>
+          <property name="buddy">
+           <cstring>uiStyleCO</cstring>
+          </property>
+         </widget>
+        </item>
+        <item row="2" column="1">
+         <widget class="QComboBox" name="uiStyleCO">
+          <property name="toolTip">
+           <string>Only certain styles may support dark mode, e.g. fusion on Windows</string>
+          </property>
+         </widget>
+        </item>
+        <item row="2" column="2">
+         <layout class="QHBoxLayout" name="horizontalLayout_2"/>
         </item>
        </layout>
       </item>