Improve CJK fonts rendering under Windows.

Author: gonwan

src/main.cpp

@@ -33,6 +33,10 @@
 	typedef QApplication  UchmviewerApp;
 #endif
 
+#ifdef _WIN32
+	#include <windows.h>
+#endif
+
 #if defined USE_DBUS
 	#include <QDBusConnection>
 	#include "dbus_interface.h"
@@ -45,6 +49,51 @@
 MainWindow* mainWindow;
 
 
+void fallbackFonts()
+{
+#ifdef _WIN32
+	// Obtain default GUI font (typically "Segoe UI, 9pt", see QTBUG-58610)
+	QFont systemFont = QApplication::font("QMessageBox");
+	LANGID lid = GetUserDefaultLangID();
+	QStringList result;
+	switch ( lid & 0xff )
+	{
+	case LANG_CHINESE:
+		if ( lid == 0x0804 || lid == 0x1004 )  // China mainland and Singapore
+			result << "Microsoft YaHei UI" << "Microsoft YaHei" << "Arial"
+				<< "Microsoft JhengHei UI" << "Microsoft JhengHei" << "Malgun Gothic" << "Yu Gothic UI" << "Meiryo UI"
+				<< "Yu Gothic" << "Meiryo";
+		else
+			result << "Microsoft JhengHei UI" << "Microsoft JhengHei" << "Arial"
+				<< "Microsoft YaHei UI" << "Microsoft YaHei" << "Malgun Gothic" << "Yu Gothic UI" << "Meiryo UI"
+				<< "Yu Gothic" << "Meiryo";
+		break;
+	case LANG_JAPANESE:
+		result << "Yu Gothic UI" << "Meiryo UI" << "Yu Gothic" << "Meiryo" << "Arial"
+			<< "Malgun Gothic" << "Microsoft YaHei UI" << "Microsoft YaHei" << "Microsoft JhengHei UI" << "Microsoft JhengHei";
+		break;
+	case LANG_KOREAN:
+		result << "Malgun Gothic" << "Arial"
+			<< "Microsoft JhengHei UI" << "Microsoft JhengHei" << "Microsoft YaHei UI" << "Microsoft YaHei"
+			<< "Yu Gothic UI" << "Meiryo UI" << "Yu Gothic" << "Meiryo";
+		break;
+	default:
+		result << "Arial" << "Yu Gothic UI" << "Meiryo UI" << "Yu Gothic" << "Meiryo" << "Malgun Gothic"
+			<< "Microsoft JhengHei UI" << "Microsoft JhengHei" << "Microsoft YaHei UI" << "Microsoft YaHei";
+		break;
+	}
+	result << "Nirmala UI"
+		<< "Iskoola Pota"
+		<< "Ebrima"
+		<< "Arial Unicode MS"
+		<< "Segoe UI Emoji"
+		<< "Segoe UI Symbol";
+	systemFont.insertSubstitutions(systemFont.family(), result);
+	systemFont.setHintingPreference(QFont::PreferNoHinting);
+	QApplication::setFont(systemFont);
+#endif
+}
+
 int main( int argc, char** argv )
 {
 #if QT_VERSION >= 0x050600
@@ -72,6 +121,8 @@ int main( int argc, char** argv )
 	app.addLibraryPath( "qt-plugins" );
 #endif
 
+	fallbackFonts();
+
 	app_i18n::init();
 
 	// Set data for QSettings