WIP Refactoring of exceptions:

1) All slicer's exceptions are now derived from Slic3r::Exception.
2) New exceptions are defined for slicing errors.
3) Exceptions are propagated to the Plater to show.
It remains to modify the slicing back-end to throw the new SlicingError
exceptions instead of std::runtime_error and to show the other exceptions
by a message dialog instead of a notification.

src/slic3r/GUI/3DScene.cpp

@@ -1926,7 +1926,7 @@ void _3DScene::extrusionentity_to_verts(const ExtrusionEntity *extrusion_entity,
                     if (extrusion_entity_collection != nullptr)
                         extrusionentity_to_verts(*extrusion_entity_collection, print_z, copy, volume);
                     else {
-                        throw std::runtime_error("Unexpected extrusion_entity type in to_verts()");
+                        throw Slic3r::RuntimeError("Unexpected extrusion_entity type in to_verts()");
                     }
                 }
             }

src/slic3r/GUI/BackgroundSlicingProcess.cpp

@@ -41,6 +41,36 @@
 
 namespace Slic3r {
 
+bool SlicingProcessCompletedEvent::critical_error() const
+{
+	try {
+		this->rethrow_exception();
+	} catch (const Slic3r::SlicingError &ex) {
+		// Exception derived from SlicingError is non-critical.
+		return false;
+	} catch (...) {
+		return true;
+	}
+}
+
+std::string SlicingProcessCompletedEvent::format_error_message() const
+{
+	std::string error;
+	try {
+		this->rethrow_exception();
+    } catch (const std::bad_alloc& ex) {
+        wxString errmsg = GUI::from_u8((boost::format(_utf8(L("%s has encountered an error. It was likely caused by running out of memory. "
+                              "If you are sure you have enough RAM on your system, this may also be a bug and we would "
+                              "be glad if you reported it."))) % SLIC3R_APP_NAME).str());
+        error = std::string(errmsg.ToUTF8()) + "\n\n" + std::string(ex.what());
+    } catch (std::exception &ex) {
+		error = ex.what();
+	} catch (...) {
+		error = "Unknown C++ exception.";
+	}
+	return error;
+}
+
 BackgroundSlicingProcess::BackgroundSlicingProcess()
 {
     boost::filesystem::path temp_path(wxStandardPaths::Get().GetTempDir().utf8_str().data());
@@ -109,19 +139,19 @@ void BackgroundSlicingProcess::process_fff()
 			switch (copy_ret_val) {
 			case SUCCESS: break; // no error
 			case FAIL_COPY_FILE:
-				throw std::runtime_error(_utf8(L("Copying of the temporary G-code to the output G-code failed. Maybe the SD card is write locked?")));
+				throw Slic3r::RuntimeError(_utf8(L("Copying of the temporary G-code to the output G-code failed. Maybe the SD card is write locked?")));
 				break;
 			case FAIL_FILES_DIFFERENT: 
-				throw std::runtime_error((boost::format(_utf8(L("Copying of the temporary G-code to the output G-code failed. There might be problem with target device, please try exporting again or using different device. The corrupted output G-code is at %1%.tmp."))) % export_path).str());
+				throw Slic3r::RuntimeError((boost::format(_utf8(L("Copying of the temporary G-code to the output G-code failed. There might be problem with target device, please try exporting again or using different device. The corrupted output G-code is at %1%.tmp."))) % export_path).str());
 				break;
 			case FAIL_RENAMING: 
-				throw std::runtime_error((boost::format(_utf8(L("Renaming of the G-code after copying to the selected destination folder has failed. Current path is %1%.tmp. Please try exporting again."))) % export_path).str()); 
+				throw Slic3r::RuntimeError((boost::format(_utf8(L("Renaming of the G-code after copying to the selected destination folder has failed. Current path is %1%.tmp. Please try exporting again."))) % export_path).str()); 
 				break;
 			case FAIL_CHECK_ORIGIN_NOT_OPENED: 
-				throw std::runtime_error((boost::format(_utf8(L("Copying of the temporary G-code has finished but the original code at %1% couldn't be opened during copy check. The output G-code is at %2%.tmp."))) % m_temp_output_path % export_path).str());
+				throw Slic3r::RuntimeError((boost::format(_utf8(L("Copying of the temporary G-code has finished but the original code at %1% couldn't be opened during copy check. The output G-code is at %2%.tmp."))) % m_temp_output_path % export_path).str());
 				break;
 			case FAIL_CHECK_TARGET_NOT_OPENED: 
-				throw std::runtime_error((boost::format(_utf8(L("Copying of the temporary G-code has finished but the exported code couldn't be opened during copy check. The output G-code is at %1%.tmp."))) % export_path).str()); 
+				throw Slic3r::RuntimeError((boost::format(_utf8(L("Copying of the temporary G-code has finished but the exported code couldn't be opened during copy check. The output G-code is at %1%.tmp."))) % export_path).str()); 
 				break;
 			default:
 				BOOST_LOG_TRIVIAL(warning) << "Unexpected fail code(" << (int)copy_ret_val << ") durring copy_file() to " << export_path << ".";
@@ -210,7 +240,7 @@ void BackgroundSlicingProcess::thread_proc()
 		// Process the background slicing task.
 		m_state = STATE_RUNNING;
 		lck.unlock();
-		std::string error;
+		std::exception_ptr exception;
 		try {
 			assert(m_print != nullptr);
 			switch(m_print->technology()) {
@@ -221,15 +251,8 @@ void BackgroundSlicingProcess::thread_proc()
 		} catch (CanceledException & /* ex */) {
 			// Canceled, this is all right.
 			assert(m_print->canceled());
-        } catch (const std::bad_alloc& ex) {
-            wxString errmsg = GUI::from_u8((boost::format(_utf8(L("%s has encountered an error. It was likely caused by running out of memory. "
-                                  "If you are sure you have enough RAM on your system, this may also be a bug and we would "
-                                  "be glad if you reported it."))) % SLIC3R_APP_NAME).str());
-            error = std::string(errmsg.ToUTF8()) + "\n\n" + std::string(ex.what());
-        } catch (std::exception &ex) {
-			error = ex.what();
 		} catch (...) {
-			error = "Unknown C++ exception.";
+			exception = std::current_exception();
 		}
 		m_print->finalize();
 		lck.lock();
@@ -237,9 +260,9 @@ void BackgroundSlicingProcess::thread_proc()
 		if (m_print->cancel_status() != Print::CANCELED_INTERNAL) {
 			// Only post the canceled event, if canceled by user.
 			// Don't post the canceled event, if canceled from Print::apply().
-			wxCommandEvent evt(m_event_finished_id);
-            evt.SetString(GUI::from_u8(error));
-			evt.SetInt(m_print->canceled() ? -1 : (error.empty() ? 1 : 0));
+			SlicingProcessCompletedEvent evt(m_event_finished_id, 0, 
+				(m_state == STATE_CANCELED) ? SlicingProcessCompletedEvent::Cancelled :
+				exception ? SlicingProcessCompletedEvent::Error : SlicingProcessCompletedEvent::Finished, exception);
         	wxQueueEvent(GUI::wxGetApp().mainframe->m_plater, evt.Clone());
         }
 	    m_print->restart();
@@ -299,7 +322,7 @@ bool BackgroundSlicingProcess::start()
 		// The background processing thread is already running.
 		return false;
 	if (! this->idle())
-		throw std::runtime_error("Cannot start a background task, the worker thread is not idle.");
+		throw Slic3r::RuntimeError("Cannot start a background task, the worker thread is not idle.");
 	m_state = STATE_STARTED;
 	m_print->set_cancel_callback([this](){ this->stop_internal(); });
 	lck.unlock();
@@ -494,7 +517,7 @@ void BackgroundSlicingProcess::prepare_upload()
 	if (m_print == m_fff_print) {
 		m_print->set_status(95, _utf8(L("Running post-processing scripts")));
 		if (copy_file(m_temp_output_path, source_path.string()) != SUCCESS) {
-			throw std::runtime_error(_utf8(L("Copying of the temporary G-code to the output G-code failed")));
+			throw Slic3r::RuntimeError(_utf8(L("Copying of the temporary G-code to the output G-code failed")));
 		}
 		run_post_process_scripts(source_path.string(), m_fff_print->config());
         m_upload_job.upload_data.upload_path = m_fff_print->print_statistics().finalize_output_path(m_upload_job.upload_data.upload_path.string());

src/slic3r/GUI/BackgroundSlicingProcess.hpp

@@ -37,6 +37,36 @@ public:
 	PrintBase::SlicingStatus status;
 };
 
+class SlicingProcessCompletedEvent : public wxEvent
+{
+public:
+	enum StatusType {
+		Finished,
+		Cancelled,
+		Error
+	};
+
+	SlicingProcessCompletedEvent(wxEventType eventType, int winid, StatusType status, std::exception_ptr exception) :
+		wxEvent(winid, eventType), m_status(status), m_exception(exception) {}
+	virtual wxEvent* Clone() const { return new SlicingProcessCompletedEvent(*this); }
+
+	StatusType 	status()    const { return m_status; }
+	bool 		finished()  const { return m_status == Finished; }
+	bool 		success()   const { return m_status == Finished; }
+	bool 		cancelled() const { return m_status == Cancelled; }
+	bool		error() 	const { return m_status == Error; }
+	// Unhandled error produced by stdlib or a Win32 structured exception, or unhandled Slic3r's own critical exception.
+	bool 		critical_error() const;
+	// Only valid if error()
+	void 		rethrow_exception() const { assert(this->error()); assert(m_exception); std::rethrow_exception(m_exception); }
+	// Produce a human readable message to be displayed by a notification or a message box.
+	std::string format_error_message() const;
+
+private:
+	StatusType 			m_status;
+	std::exception_ptr 	m_exception;
+};
+
 wxDEFINE_EVENT(EVT_SLICING_UPDATE, SlicingStatusEvent);
 
 // Print step IDs for keeping track of the print state.

src/slic3r/GUI/ConfigExceptions.hpp

@@ -1,15 +1,15 @@
 #include <exception> 
 namespace Slic3r {
 
-class ConfigError : public std::runtime_error { 
-using std::runtime_error::runtime_error;
+class ConfigError : public Slic3r::RuntimeError { 
+	using Slic3r::RuntimeError::RuntimeError;
 };
 
 namespace GUI {
 
 class ConfigGUITypeError : public ConfigError { 
-using ConfigError::ConfigError;
+	using ConfigError::ConfigError;
 };
-}
 
-}
+} // namespace GUI
+} // namespace Slic3r

src/slic3r/GUI/ConfigWizard.cpp

@@ -123,7 +123,7 @@ Bundle& BundleMap::prusa_bundle()
 {
     auto it = find(PresetBundle::PRUSA_BUNDLE);
     if (it == end()) {
-        throw std::runtime_error("ConfigWizard: Internal error in BundleMap: PRUSA_BUNDLE not loaded");
+        throw Slic3r::RuntimeError("ConfigWizard: Internal error in BundleMap: PRUSA_BUNDLE not loaded");
     }
 
     return it->second;

src/slic3r/GUI/FirmwareDialog.cpp

@@ -766,7 +766,7 @@ const char* FirmwareDialog::priv::avr109_dev_name(Avr109Pid usb_pid) {
 			return "Original Prusa CW1";
 		break;
 
-		default: throw std::runtime_error((boost::format("Invalid avr109 device USB PID: %1%") % usb_pid.boot).str());
+		default: throw Slic3r::RuntimeError((boost::format("Invalid avr109 device USB PID: %1%") % usb_pid.boot).str());
 	}
 }
 

src/slic3r/GUI/GUI_App.cpp

@@ -571,7 +571,7 @@ void GUI_App::init_app_config()
         std::string error = app_config->load();
         if (!error.empty())
             // Error while parsing config file. We'll customize the error message and rethrow to be displayed.
-            throw std::runtime_error(
+            throw Slic3r::RuntimeError(
                 _u8L("Error parsing PrusaSlicer config file, it is probably corrupted. "
                     "Try to manually delete the file to recover from the error. Your user profiles will not be affected.") +
                 "\n\n" + AppConfig::config_path() + "\n\n" + error);

src/slic3r/GUI/ImGuiWrapper.cpp

@@ -927,7 +927,7 @@ void ImGuiWrapper::init_font(bool compress)
     if (font == nullptr) {
         font = io.Fonts->AddFontDefault();
         if (font == nullptr) {
-            throw std::runtime_error("ImGui: Could not load deafult font");
+            throw Slic3r::RuntimeError("ImGui: Could not load deafult font");
         }
     }
 

src/slic3r/GUI/OptionsGroup.cpp

@@ -7,6 +7,7 @@
 #include <wx/numformatter.h>
 #include <boost/algorithm/string/split.hpp>
 #include <boost/algorithm/string/classification.hpp>
+#include "libslic3r/Exception.hpp"
 #include "libslic3r/Utils.hpp"
 #include "I18N.hpp"
 
@@ -64,7 +65,7 @@ const t_field& OptionsGroup::build_field(const t_config_option_key& id, const Co
 				break;
             case coNone:   break;
             default:
-				throw /*//!ConfigGUITypeError("")*/std::logic_error("This control doesn't exist till now"); break;
+				throw Slic3r::LogicError("This control doesn't exist till now"); break;
         }
     }
     // Grab a reference to fields for convenience
@@ -620,7 +621,7 @@ boost::any ConfigOptionsGroup::config_value(const std::string& opt_key, int opt_
 		// Aggregate the strings the old way.
 		// Currently used for the post_process config value only.
 		if (opt_index != -1)
-			throw std::out_of_range("Can't deserialize option indexed value");
+			throw Slic3r::OutOfRange("Can't deserialize option indexed value");
 // 		return join(';', m_config->get(opt_key)});
 		return get_config_value(*m_config, opt_key);
 	}

src/slic3r/GUI/Plater.cpp

@@ -107,7 +107,7 @@ namespace GUI {
 wxDEFINE_EVENT(EVT_SCHEDULE_BACKGROUND_PROCESS,     SimpleEvent);
 wxDEFINE_EVENT(EVT_SLICING_UPDATE,                  SlicingStatusEvent);
 wxDEFINE_EVENT(EVT_SLICING_COMPLETED,               wxCommandEvent);
-wxDEFINE_EVENT(EVT_PROCESS_COMPLETED,               wxCommandEvent);
+wxDEFINE_EVENT(EVT_PROCESS_COMPLETED,               SlicingProcessCompletedEvent);
 wxDEFINE_EVENT(EVT_EXPORT_BEGAN,                    wxCommandEvent);
 
 // Sidebar widgets
@@ -1682,7 +1682,7 @@ struct Plater::priv
     void on_select_preset(wxCommandEvent&);
     void on_slicing_update(SlicingStatusEvent&);
     void on_slicing_completed(wxCommandEvent&);
-    void on_process_completed(wxCommandEvent&);
+    void on_process_completed(SlicingProcessCompletedEvent&);
 	void on_export_began(wxCommandEvent&);
     void on_layer_editing_toggled(bool enable);
 	void on_slicing_began();
@@ -3510,7 +3510,7 @@ bool Plater::priv::warnings_dialog()
 	return res == wxID_OK;
 
 }
-void Plater::priv::on_process_completed(wxCommandEvent &evt)
+void Plater::priv::on_process_completed(SlicingProcessCompletedEvent &evt)
 {
     // Stop the background task, wait until the thread goes into the "Idle" state.
     // At this point of time the thread should be either finished or canceled,
@@ -3519,27 +3519,23 @@ void Plater::priv::on_process_completed(wxCommandEvent &evt)
     this->statusbar()->reset_cancel_callback();
     this->statusbar()->stop_busy();
 
-    const bool canceled = evt.GetInt() < 0;
-    const bool error = evt.GetInt() == 0;
-    const bool success  = evt.GetInt() > 0;
     // Reset the "export G-code path" name, so that the automatic background processing will be enabled again.
     this->background_process.reset_export();
 
-    if (error) {
-        wxString message = evt.GetString();
-        if (message.IsEmpty())
-            message = _L("Export failed.");
-		notification_manager->push_slicing_error_notification(boost::nowide::narrow(message), *q->get_current_canvas3D());
-        this->statusbar()->set_status_text(message);
+    if (evt.error()) {
+        std::string message = evt.format_error_message();
+        //FIXME show a messagebox if evt.critical_error().
+		notification_manager->push_slicing_error_notification(message, *q->get_current_canvas3D());
+        this->statusbar()->set_status_text(from_u8(message));
 		const wxString invalid_str = _L("Invalid data");
 		for (auto btn : { ActionButtonType::abReslice, ActionButtonType::abSendGCode, ActionButtonType::abExport })
 			sidebar->set_btn_label(btn, invalid_str);
 		process_completed_with_error = true;
     }
-    if (canceled)
+    if (evt.cancelled())
         this->statusbar()->set_status_text(_L("Cancelled"));
 
-    this->sidebar->show_sliced_info_sizer(success);
+    this->sidebar->show_sliced_info_sizer(evt.success());
 
     // This updates the "Slice now", "Export G-code", "Arrange" buttons status.
     // Namely, it refreshes the "Out of print bed" property of all the ModelObjects, and it enables
@@ -3560,7 +3556,7 @@ void Plater::priv::on_process_completed(wxCommandEvent &evt)
     default: break;
     }
 	
-    if (canceled) {
+    if (evt.cancelled()) {
         if (wxGetApp().get_mode() == comSimple)
             sidebar->set_btn_label(ActionButtonType::abReslice, "Slice now");
         show_action_buttons(true);

src/slic3r/GUI/wxExtensions.cpp

@@ -436,7 +436,7 @@ wxBitmap create_scaled_bitmap(  const std::string& bmp_name_in,
 
     if (bmp == nullptr) {
         // Neither SVG nor PNG has been found, raise error
-        throw std::runtime_error("Could not load bitmap: " + bmp_name);
+        throw Slic3r::RuntimeError("Could not load bitmap: " + bmp_name);
     }
 
     return *bmp;