Updated the command line single-instance processing and help text.

Updated escaping of the command line arguments when passed to the other
instance.

src/libslic3r/PrintConfig.cpp

@@ -39,11 +39,6 @@ void PrintConfigDef::init_common_params()
 {
     ConfigOptionDef* def;
 
-	def = this->add("single_instance", coBool);
-	def->label = L("Single Instance");
-	def->mode = comAdvanced;
-	def->set_default_value(new ConfigOptionBool(false));
-
     def = this->add("printer_technology", coEnum);
     def->label = L("Printer technology");
     def->tooltip = L("Printer technology");
@@ -3698,6 +3693,12 @@ CLIMiscConfigDef::CLIMiscConfigDef()
     def->tooltip = L("The file where the output will be written (if not specified, it will be based on the input file).");
     def->cli = "output|o";
 
+    def = this->add("single_instance", coBool);
+    def->label = L("Single Instance");
+    def->tooltip = L("If enabled, the command line arguments are sent to an existing instance of GUI PrusaSlicer, "
+                     "or an existing PrusaSlicer window is activated. "
+                     "Overrides the \"single_instance\" configuration value from application preferences.");
+
 /*
     def = this->add("autosave", coString);
     def->label = L("Autosave");

src/slic3r/GUI/InstanceCheck.cpp

@@ -15,6 +15,7 @@
 #include <unordered_map>
 #include <fcntl.h>
 #include <errno.h>
+#include <optional>
 
 #ifdef _WIN32
 #include <strsafe.h>
@@ -29,25 +30,29 @@ namespace instance_check_internal
 {
 	struct CommandLineAnalysis
 	{
-		bool           should_send;
+		std::optional<bool>	should_send;
-		std::string    cl_string;
+		std::string    		cl_string;
 	};
 	static CommandLineAnalysis process_command_line(int argc, char** argv)
 	{
 		CommandLineAnalysis ret { false };
 		if (argc < 2)
 			return ret;
-		ret.cl_string = escape_string_cstyle(argv[0]);
+		std::vector<std::string> arguments { argv[0] };
 		for (size_t i = 1; i < argc; ++i) {
 			const std::string token = argv[i];
-			if (token == "--single-instance" || token == "--single-instance=1") {
+			// Processing of boolean command line arguments shall match DynamicConfig::read_cli().
+			if (token == "--single-instance")
 				ret.should_send = true;
-			} else {
+			else if (token == "--no-single-instance")
-				ret.cl_string += " : ";
+				ret.should_send = false;
-				ret.cl_string += escape_string_cstyle(token);
+			else
-			}
+				arguments.emplace_back(token);
 		} 
-		BOOST_LOG_TRIVIAL(debug) << "single instance: "<< ret.should_send << ". other params: " << ret.cl_string;
+		ret.cl_string = escape_strings_cstyle(arguments);
+		BOOST_LOG_TRIVIAL(debug) << "single instance: " << 
+			(ret.should_send.has_value() ? (ret.should_send.value() ? "true" : "false") : "undefined") << 
+			". other params: " << ret.cl_string;
 		return ret;
 	}
 
@@ -243,11 +248,13 @@ bool instance_check(int argc, char** argv, bool app_config_single_instance)
 	GUI::wxGetApp().set_instance_hash(hashed_path);
 	BOOST_LOG_TRIVIAL(debug) <<"full path: "<< lock_name;
 	instance_check_internal::CommandLineAnalysis cla = instance_check_internal::process_command_line(argc, argv);
+	if (! cla.should_send.has_value())
+		cla.should_send = app_config_single_instance;
 #ifdef _WIN32
 	GUI::wxGetApp().init_single_instance_checker(lock_name + ".lock", data_dir() + "/cache/");
-	if ((cla.should_send || app_config_single_instance) && GUI::wxGetApp().single_instance_checker()->IsAnotherRunning()) {
+	if (cla.should_send.value() && GUI::wxGetApp().single_instance_checker()->IsAnotherRunning()) {
 #else // mac & linx
-	if ((cla.should_send || app_config_single_instance) && instance_check_internal::get_lock(lock_name + ".lock", data_dir() + "/cache/")) {
+	if (cla.should_send.value() && instance_check_internal::get_lock(lock_name + ".lock", data_dir() + "/cache/")) {
 #endif
 		instance_check_internal::send_message(cla.cl_string, lock_name);
 		BOOST_LOG_TRIVIAL(info) << "instance check: Another instance found. This instance will terminate.";
@@ -372,32 +379,27 @@ namespace MessageHandlerInternal
 	}
 } //namespace MessageHandlerInternal
 
-void OtherInstanceMessageHandler::handle_message(const std::string& message) {
+void OtherInstanceMessageHandler::handle_message(const std::string& message) 
-	std::vector<boost::filesystem::path> paths;
+{
-	auto                                 next_space = message.find(" : ");
-	size_t                               last_space = 0;
-	int                                  counter    = 0;
-
 	BOOST_LOG_TRIVIAL(info) << "message from other instance: " << message;
 
-	while (next_space != std::string::npos)
+	std::vector<std::string> args;
-	{	
+	bool parsed = unescape_strings_cstyle(message, args);
-		if (counter != 0) {
+	assert(parsed);
-			std::string possible_path = message.substr(last_space, next_space - last_space);
+	if (! parsed) {
-			boost::filesystem::path p = MessageHandlerInternal::get_path(std::move(possible_path));
+		BOOST_LOG_TRIVIAL(error) << "message from other instance is incorrectly formatted: " << message;
-			if(!p.string().empty())
+		return;
-				paths.emplace_back(p);
-		}
-		last_space = next_space + 3;
-		next_space = message.find(" : ", last_space);
-		counter++;
 	}
-	if (counter != 0 ) {
+
-		boost::filesystem::path p = MessageHandlerInternal::get_path(message.substr(last_space));
+	std::vector<boost::filesystem::path> paths;
-		if (!p.string().empty())
+	// Skip the first argument, it is the path to the slicer executable.
+	auto it = args.begin();
+	for (++ it; it != args.end(); ++ it) {
+		boost::filesystem::path p = MessageHandlerInternal::get_path(*it);
+		if (! p.string().empty())
 			paths.emplace_back(p);
 	}
-	if (!paths.empty()) {
+	if (! paths.empty()) {
 		//wxEvtHandler* evt_handler = wxGetApp().plater(); //assert here?
 		//if (evt_handler) {
 			wxPostEvent(m_callback_evt_handler, LoadFromOtherInstanceEvent(GUI::EVT_LOAD_MODEL_OTHER_INSTANCE, std::vector<boost::filesystem::path>(std::move(paths))));