Refactoring to finally get rid of MessageHandler/Receiver in favor of the new Settings mechanism.

35 files changed, 406 insertions, 937 deletions

diff --git a/drumgizmo/drumgizmoc.cc b/drumgizmo/drumgizmoc.cc
index 357877d..e993dc3 100644
--- a/drumgizmo/drumgizmoc.cc
+++ b/drumgizmo/drumgizmoc.cc
@@ -92,36 +92,7 @@ static const char usage_str[] =
     "  dummy:\n"
     "\n";
 
-CliMain::CliMain()
-	: MessageReceiver(MSGRCV_UI)
-{
-	loading = true; // Block by default
-}
-
-CliMain::~CliMain()
-{
-	hug_close();
-}
-
-void CliMain::handleMessage(Message* msg)
-{
-	switch(msg->type())
-	{
-	case Message::LoadStatus:
-		{
-			auto ls = static_cast<LoadStatusMessage*>(msg);
-			if(ls->numer_of_files_loaded == ls->number_of_files)
-			{
-				loading = false;
-			}
-		}
-		break;
-	default:
-		break;
-	}
-}
-
-int CliMain::run(int argc, char* argv[])
+int main(int argc, char* argv[])
 {
 	int c;
 
@@ -383,21 +354,37 @@ int CliMain::run(int argc, char* argv[])
 		return 1;
 	}
 
-	printf("Loading drumkit, this may take a while...");
-	fflush(stdout);
-	loading = true;
-	while(async == false && loading)
+	printf("Loading drumkit, this may take a while:\n");
+
+	if(!async)
 	{
+		while(settings.drumkit_load_status.load() != LoadStatus::Done)
+		{
 #ifdef WIN32
-		SleepEx(500, FALSE);
+			SleepEx(10, FALSE);
 #else
-		usleep(500000);
+			usleep(10000);
 #endif /*WIN32*/
-		handleMessages();
-		printf(".");
-		fflush(stdout);
+
+			int total = settings.number_of_files.load();
+			int loaded =  settings.number_of_files_loaded.load();
+
+			printf("\r%d of %d     ", loaded, total);
+			fflush(stdout);
+
+			if(settings.drumkit_load_status.load() == LoadStatus::Error)
+			{
+				printf("\nLoad error\n");
+				return 1;
+			}
+
+			if(loaded == total)
+			{
+				//break;
+			}
+		}
+		printf("\ndone\n");
 	}
-	printf("done.\n");
 
 	gizmo.setSamplerate(oe->getSamplerate());
 
@@ -412,14 +399,7 @@ int CliMain::run(int argc, char* argv[])
 	printf("Quit.\n");
 	fflush(stdout);
 
-	return 0;
-}
-
-int main(int argc, char* argv[])
-{
-	CliMain cli;
-
-	cli.run(argc, argv);
+	hug_close();
 
 	return 0;
 }
diff --git a/drumgizmo/drumgizmoc.h b/drumgizmo/drumgizmoc.h
index 231aec6..cc2f96c 100644
--- a/drumgizmo/drumgizmoc.h
+++ b/drumgizmo/drumgizmoc.h
@@ -24,21 +24,4 @@
  *  along with DrumGizmo; if not, write to the Free Software
  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
  */
-
 #pragma once
-
-#include "messagereceiver.h"
-
-class CliMain : public MessageReceiver
-{
-public:
-	CliMain();
-	virtual ~CliMain();
-
-	int run(int argc, char* argv[]);
-	void handleMessage(Message* msg);
-
-private:
-	bool loading;
-};
-
diff --git a/plugin/Makefile.mingw32.in b/plugin/Makefile.mingw32.in
index 779f54b..8b341c7 100644
--- a/plugin/Makefile.mingw32.in
+++ b/plugin/Makefile.mingw32.in
@@ -28,8 +28,6 @@ DG_SRC = \
 	@top_srcdir@/src/instrument.cc \
 	@top_srcdir@/src/instrumentparser.cc \
 	@top_srcdir@/src/memchecker.cc \
-	@top_srcdir@/src/messagehandler.cc \
-	@top_srcdir@/src/messagereceiver.cc \
 	@top_srcdir@/src/midimapparser.cc \
 	@top_srcdir@/src/midimapper.cc \
 	@top_srcdir@/src/mutex.cc \
diff --git a/plugin/drumgizmo_plugin.cc b/plugin/drumgizmo_plugin.cc
index 24cfb9a..06c2799 100644
--- a/plugin/drumgizmo_plugin.cc
+++ b/plugin/drumgizmo_plugin.cc
@@ -143,7 +143,7 @@ bool DrumGizmoPlugin::hasGUI()
 
 void DrumGizmoPlugin::createWindow(void *parent)
 {
-	plugin_gui = std::make_shared<GUI::PluginGUI>(parent);
+	plugin_gui = std::make_shared<GUI::PluginGUI>(settings, parent);
 	resizeWindow(370, 330);
 	onShowWindow();
 }
diff --git a/plugingui/Makefile.am b/plugingui/Makefile.am
index 3dee864..4176c07 100644
--- a/plugingui/Makefile.am
+++ b/plugingui/Makefile.am
@@ -16,9 +16,7 @@ plugingui_SOURCES = \
 	$(top_srcdir)/src/configfile.cc \
 	$(top_srcdir)/src/thread.cc \
 	$(top_srcdir)/src/semaphore.cc \
-	$(top_srcdir)/src/mutex.cc \
-	$(top_srcdir)/src/messagehandler.cc \
-	$(top_srcdir)/src/messagereceiver.cc
+	$(top_srcdir)/src/mutex.cc
 
 rcgen_SOURCES = rcgen.cc
 
@@ -46,7 +44,6 @@ EXTRA_DIST = \
 	nativewindow.h \
 	nativewindow_win32.h \
 	nativewindow_x11.h \
-	notifier.h \
 	painter.h \
 	pixelbuffer.h \
 	pluginconfig.h \
diff --git a/plugingui/button.h b/plugingui/button.h
index 7e3e168..1bfeb2d 100644
--- a/plugingui/button.h
+++ b/plugingui/button.h
@@ -28,9 +28,10 @@
 
 #include <string>
 
+#include <notifier.h>
+
 #include "widget.h"
 #include "painter.h"
-#include "notifier.h"
 #include "font.h"
 
 namespace GUI {
diff --git a/plugingui/checkbox.h b/plugingui/checkbox.h
index 3da5511..5c658a5 100644
--- a/plugingui/checkbox.h
+++ b/plugingui/checkbox.h
@@ -26,9 +26,10 @@
  */
 #pragma once
 
+#include <notifier.h>
+
 #include "widget.h"
 #include "image.h"
-#include "notifier.h"
 
 namespace GUI {
 
diff --git a/plugingui/dgwindow.cc b/plugingui/dgwindow.cc
index 25cbdf0..c325703 100644
--- a/plugingui/dgwindow.cc
+++ b/plugingui/dgwindow.cc
@@ -30,12 +30,12 @@
 #include "verticalline.h"
 #include "../version.h"
 
-#include "messagehandler.h"
 #include "pluginconfig.h"
 
 namespace GUI {
 
-class LabeledControl : public Widget
+class LabeledControl
+	: public Widget
 {
 public:
 	LabeledControl(Widget* parent, const std::string& name)
@@ -60,7 +60,8 @@ public:
 	Label caption{this};
 };
 
-class File : public Widget
+class File
+	: public Widget
 {
 public:
 	File(Widget* parent)
@@ -83,7 +84,8 @@ public:
 	Button browseButton{this};
 };
 
-class HumanizeControls : public Widget
+class HumanizeControls
+	: public Widget
 {
 public:
 	HumanizeControls(Widget* parent)
@@ -119,10 +121,8 @@ public:
 	Knob falloffKnob{&falloff};
 };
 
-DGWindow::DGWindow(void* native_window, MessageHandler& messageHandler,
-                   Config& config, Settings& settings)
+DGWindow::DGWindow(void* native_window, Config& config, Settings& settings)
 	: Window(native_window)
-	, messageHandler(messageHandler)
 	, config(config)
 	, settings(settings)
 {
@@ -180,6 +180,7 @@ DGWindow::DGWindow(void* native_window, MessageHandler& messageHandler,
 
 	midimapFileProgress = new ProgressBar(this);
 	midimapFileProgress->resize(width() - 40, 11);
+	midimapFileProgress->setTotal(2);
 	layout.addItem(midimapFileProgress);
 
 	VerticalLine *l2 = new VerticalLine(this);
@@ -208,7 +209,7 @@ DGWindow::DGWindow(void* native_window, MessageHandler& messageHandler,
 	layout.addItem(l3);
 
 	Label *lbl_version = new Label(this);
-	lbl_version->setText(".::. v" VERSION "  .::.  http://www.drumgizmo.org  .::.  LGPLv3 .::.");
+	lbl_version->setText(".::.  v" VERSION "  .::.  http://www.drumgizmo.org  .::.  LGPLv3 .::.");
 	lbl_version->resize(width(), 20);
 	lbl_version->setAlignment(TextAlignment::center);
 	layout.addItem(lbl_version);
@@ -220,6 +221,50 @@ DGWindow::DGWindow(void* native_window, MessageHandler& messageHandler,
 	fileBrowser->hide();
 }
 
+void DGWindow::setDrumKitLoadStatus(LoadStatus load_status)
+{
+	ProgressBarState state = ProgressBarState::Blue;
+	switch(load_status)
+	{
+	case LoadStatus::Idle:
+	case LoadStatus::Loading:
+		state = ProgressBarState::Blue;
+		break;
+	case LoadStatus::Done:
+		state = ProgressBarState::Green;
+		break;
+	case LoadStatus::Error:
+		state = ProgressBarState::Red;
+		break;
+	}
+	drumkitFileProgress->setState(state);
+}
+
+void DGWindow::setMidiMapLoadStatus(LoadStatus load_status)
+{
+	ProgressBarState state = ProgressBarState::Blue;
+	switch(load_status)
+	{
+	case LoadStatus::Idle:
+		midimapFileProgress->setValue(0);
+		break;
+	case LoadStatus::Loading:
+		midimapFileProgress->setValue(1);
+		state = ProgressBarState::Blue;
+		break;
+	case LoadStatus::Done:
+		midimapFileProgress->setValue(2);
+		state = ProgressBarState::Green;
+		break;
+	case LoadStatus::Error:
+		midimapFileProgress->setValue(2);
+		state = ProgressBarState::Red;
+		break;
+	}
+
+	midimapFileProgress->setState(state);
+}
+
 void DGWindow::repaintEvent(RepaintEvent* repaintEvent)
 {
 	if(!visible())
@@ -234,45 +279,41 @@ void DGWindow::repaintEvent(RepaintEvent* repaintEvent)
 
 void DGWindow::attackValueChanged(float value)
 {
-	//ChangeSettingMessage *msg =
-	//	new ChangeSettingMessage(ChangeSettingMessage::velocity_modifier_weight,
-	//													 value);
-	//messageHandler.sendMessage(MSGRCV_ENGINE, msg);
-
 	settings.velocity_modifier_weight.store(value);
 
-#ifdef STANDALONE
+#ifdef STANDALONE // For GUI debugging
 	int i = value * 4;
 	switch(i) {
-	case 0: drumkitFileProgress->setState(ProgressBarState::Off); break;
-	case 1: drumkitFileProgress->setState(ProgressBarState::Blue); break;
-	case 2: drumkitFileProgress->setState(ProgressBarState::Green); break;
-	case 3: drumkitFileProgress->setState(ProgressBarState::Red); break;
-	default: break;
+	case 0:
+		drumkitFileProgress->setState(ProgressBarState::Off);
+		break;
+	case 1:
+		drumkitFileProgress->setState(ProgressBarState::Blue);
+		break;
+	case 2:
+		drumkitFileProgress->setState(ProgressBarState::Green);
+		break;
+	case 3:
+		drumkitFileProgress->setState(ProgressBarState::Red);
+		break;
+	default:
+		break;
 	}
 #endif
 }
 
 void DGWindow::falloffValueChanged(float value)
 {
-	//ChangeSettingMessage *msg =
-	//	new ChangeSettingMessage(ChangeSettingMessage::velocity_modifier_falloff,
-	//	                         value);
-	//messageHandler.sendMessage(MSGRCV_ENGINE, msg);
-
 	settings.velocity_modifier_falloff.store(value);
 
-#ifdef STANDALONE
-	drumkitFileProgress->setProgress(value);
+#ifdef STANDALONE // For GUI debugging
+	drumkitFileProgress->setTotal(100);
+	drumkitFileProgress->setValue(value * 100);
 #endif
 }
 
 void DGWindow::velocityCheckClick(bool checked)
 {
-//	ChangeSettingMessage *msg =
-//		new ChangeSettingMessage(ChangeSettingMessage::enable_velocity_modifier,
-//		                         checked);
-//	messageHandler.sendMessage(MSGRCV_ENGINE, msg);
 	settings.enable_velocity_modifier.store(checked);
 }
 
@@ -323,13 +364,7 @@ void DGWindow::selectKitFile(const std::string& filename)
 	config.lastkit = drumkit;
 	config.save();
 
-	drumkitFileProgress->setProgress(0);
-	drumkitFileProgress->setState(ProgressBarState::Blue);
-
-	LoadDrumKitMessage *msg = new LoadDrumKitMessage();
-	msg->drumkitfile = drumkit;
-
-	messageHandler.sendMessage(MSGRCV_ENGINE, msg);
+	settings.drumkit_file.store(drumkit);
 }
 
 void DGWindow::selectMapFile(const std::string& filename)
@@ -342,9 +377,7 @@ void DGWindow::selectMapFile(const std::string& filename)
 	config.lastmidimap = midimap;
 	config.save();
 
-	LoadMidimapMessage *msg = new LoadMidimapMessage();
-	msg->midimapfile = midimap;
-	messageHandler.sendMessage(MSGRCV_ENGINE, msg);
+	settings.midimap_file.store(midimap);
 }
 
 
diff --git a/plugingui/dgwindow.h b/plugingui/dgwindow.h
index c4fbeab..72e4679 100644
--- a/plugingui/dgwindow.h
+++ b/plugingui/dgwindow.h
@@ -26,8 +26,9 @@
  */
 #pragma once
 
-#include "window.h"
+#include <settings.h>
 
+#include "window.h"
 #include "label.h"
 #include "lineedit.h"
 #include "checkbox.h"
@@ -37,10 +38,6 @@
 #include "filebrowser.h"
 #include "layout.h"
 
-#include <settings.h>
-
-class MessageHandler;
-
 namespace GUI {
 
 class Config;
@@ -49,8 +46,7 @@ class File;
 
 class DGWindow : public Window {
 public:
-	DGWindow(void* native_window, MessageHandler& messageHandler, Config& config,
-	         Settings& settings);
+	DGWindow(void* native_window, Config& config, Settings& settings);
 
 	Header* header;
 
@@ -68,6 +64,9 @@ public:
 	Knob* falloffKnob;
 	FileBrowser* fileBrowser;
 
+	void setDrumKitLoadStatus(LoadStatus load_status);
+	void setMidiMapLoadStatus(LoadStatus load_status);
+
 protected:
 	// From Widget:
 	void repaintEvent(RepaintEvent* repaintEvent) override;
@@ -81,7 +80,6 @@ private:
 	void selectKitFile(const std::string& filename);
 	void selectMapFile(const std::string& filename);
 
-	MessageHandler& messageHandler;
 	Config& config;
 
 	VBoxLayout layout{this};
diff --git a/plugingui/eventhandler.h b/plugingui/eventhandler.h
index 1fdb1e8..490c515 100644
--- a/plugingui/eventhandler.h
+++ b/plugingui/eventhandler.h
@@ -26,9 +26,10 @@
  */
 #pragma once
 
+#include <notifier.h>
+
 #include "guievent.h"
 #include "nativewindow.h"
-#include "notifier.h"
 
 namespace GUI {
 
diff --git a/plugingui/filebrowser.h b/plugingui/filebrowser.h
index 04b34f6..bc2019f 100644
--- a/plugingui/filebrowser.h
+++ b/plugingui/filebrowser.h
@@ -26,15 +26,15 @@
  */
 #pragma once
 
-#include "widget.h"
+#include <notifier.h>
 
+#include "widget.h"
 #include "button.h"
 #include "listbox.h"
 #include "lineedit.h"
 #include "label.h"
 #include "image.h"
 #include "directory.h"
-#include "notifier.h"
 
 namespace GUI {
 
diff --git a/plugingui/knob.h b/plugingui/knob.h
index 10d91d6..d144184 100644
--- a/plugingui/knob.h
+++ b/plugingui/knob.h
@@ -26,10 +26,11 @@
  */
 #pragma once
 
+#include <notifier.h>
+
 #include "widget.h"
 #include "image.h"
 #include "font.h"
-#include "notifier.h"
 
 namespace GUI {
 
diff --git a/plugingui/layout.h b/plugingui/layout.h
index 55cc93f..49bf75c 100644
--- a/plugingui/layout.h
+++ b/plugingui/layout.h
@@ -29,7 +29,7 @@
 #include <list>
 #include <cstdlib>
 
-#include "notifier.h"
+#include <notifier.h>
 
 namespace GUI {
 
diff --git a/plugingui/listboxbasic.h b/plugingui/listboxbasic.h
index 7953dc3..2ebe845 100644
--- a/plugingui/listboxbasic.h
+++ b/plugingui/listboxbasic.h
@@ -29,11 +29,12 @@
 #include <string.h>
 #include <vector>
 
+#include <notifier.h>
+
 #include "widget.h"
 #include "font.h"
 #include "painter.h"
 #include "scrollbar.h"
-#include "notifier.h"
 
 namespace GUI {
 
diff --git a/plugingui/listboxthin.h b/plugingui/listboxthin.h
index 3139ecc..1617234 100644
--- a/plugingui/listboxthin.h
+++ b/plugingui/listboxthin.h
@@ -29,10 +29,11 @@
 #include <string.h>
 #include <vector>
 
+#include <notifier.h>
+
 #include "widget.h"
 #include "painter.h"
 #include "listboxbasic.h"
-#include "notifier.h"
 
 namespace GUI {
 
diff --git a/plugingui/plugingui.cc b/plugingui/plugingui.cc
index 9bac007..2802c44 100644
--- a/plugingui/plugingui.cc
+++ b/plugingui/plugingui.cc
@@ -26,18 +26,17 @@
  */
 #include "plugingui.h"
 
+#include <iostream>
+
 #include <hugin.hpp>
 
 #include "pluginconfig.h"
-#include "messagehandler.h"
-
-#include <iostream>
 
 namespace GUI {
 
-PluginGUI::PluginGUI(void* native_window)
-	: MessageReceiver(MSGRCV_UI)
-	, native_window(native_window)
+PluginGUI::PluginGUI(Settings& settings, void* native_window)
+	: native_window(native_window)
+	, settings(settings)
 {
 	init();
 }
@@ -46,70 +45,6 @@ PluginGUI::~PluginGUI()
 {
 }
 
-void PluginGUI::handleMessage(Message *msg)
-{
-	Painter p(*window);// Make sure we only redraw buffer once (set refcount to 1)
-
-	switch(msg->type()) {
-	case Message::LoadStatus:
-		{
-			LoadStatusMessage *ls = (LoadStatusMessage*)msg;
-			window->drumkitFileProgress->setProgress((float)ls->numer_of_files_loaded /
-			                              (float)ls->number_of_files);
-			if(ls->numer_of_files_loaded == ls->number_of_files)
-			{
-				window->drumkitFileProgress->setState(ProgressBarState::Green);
-			}
-		}
-		break;
-	case Message::LoadStatusMidimap:
-		{
-			LoadStatusMessageMidimap *ls = (LoadStatusMessageMidimap*)msg;
-			window->midimapFileProgress->setProgress(1);
-			if(ls->success)
-			{
-				window->midimapFileProgress->setState(ProgressBarState::Green);
-			}
-			else
-			{
-				window->midimapFileProgress->setState(ProgressBarState::Red);
-			}
-		}
-		break;
-	case Message::EngineSettingsMessage:
-		{
-			EngineSettingsMessage *settings = (EngineSettingsMessage *)msg;
-			window->lineedit->setText(settings->drumkitfile);
-			if(settings->drumkit_loaded)
-			{
-				window->drumkitFileProgress->setProgress(1);
-				window->drumkitFileProgress->setState(ProgressBarState::Green);
-			}
-			else
-			{
-				window->drumkitFileProgress->setProgress(0);
-				window->drumkitFileProgress->setState(ProgressBarState::Blue);
-			}
-			window->lineedit2->setText(settings->midimapfile);
-			if(settings->midimap_loaded)
-			{
-				window->midimapFileProgress->setProgress(1);
-				window->midimapFileProgress->setState(ProgressBarState::Green);
-			}
-			else
-			{
-				window->midimapFileProgress->setProgress(0);
-				window->midimapFileProgress->setState(ProgressBarState::Blue);
-			}
-			window->velocityCheck->setChecked(settings->enable_velocity_modifier);
-			window->attackKnob->setValue(settings->velocity_modifier_weight);
-			window->falloffKnob->setValue(settings->velocity_modifier_falloff);
-		}
-	default:
-		break;
-	}
-}
-
 bool PluginGUI::processEvents()
 {
 	if(!initialised)
@@ -118,69 +53,13 @@ bool PluginGUI::processEvents()
 	}
 
 	window->eventHandler()->processEvents();
-	//handleMessages();
-
-	static bool foo = false;
-	static int t = 0;
-	if(t != time(nullptr))
-	{
-		t = time(nullptr);
-		foo = !foo;
-		float v = settings.velocity_modifier_falloff.load();
-		v += 0.1f;
-		settings.velocity_modifier_falloff.store(v);
-	}
-
-	Painter p(*window);
-
-	// Run through all settings one at a time propagate changes to the UI.
-	if(getter.enable_velocity_modifier.hasChanged())
-	{
-		enable_velocity_modifier_notifier(getter.enable_velocity_modifier.getValue());
-	}
 
-	if(getter.velocity_modifier_falloff.hasChanged())
 	{
-		velocity_modifier_falloff_notifier(getter.velocity_modifier_falloff.getValue());
-	}
+		Painter p(*window);
 
-	if(getter.velocity_modifier_weight.hasChanged())
-	{
-		velocity_modifier_weight_notifier(getter.velocity_modifier_weight.getValue());
-	}
-
-	if(getter.enable_velocity_randomiser.hasChanged())
-	{
-		enable_velocity_randomiser_notifier(getter.enable_velocity_randomiser.getValue());
+		settings_notifier.evaluate();
 	}
 
-	if(getter.velocity_randomiser_weight.hasChanged())
-	{
-		velocity_randomiser_weight_notifier(getter.velocity_randomiser_weight.getValue());
-	}
-
-	if(getter.samplerate.hasChanged())
-	{
-		samplerate_notifier(getter.samplerate.getValue());
-	}
-
-	if(getter.enable_resampling.hasChanged())
-	{
-		enable_resampling_notifier(getter.enable_resampling.getValue());
-	}
-
-	if(getter.number_of_files.hasChanged() ||
-	   getter.number_of_files_loaded.hasChanged())
-	{
-		drumkit_file_progress_notifier((float)getter.number_of_files_loaded.getValue() /
-		                               (float)getter.number_of_files.getValue());
-	}
-
-	//if(getter.current_file.hasChanged())
-	//{
-	//	current_file_notifier(getter.current_file.getValue());
-	//}
-
 	if(closing)
 	{
 		closeNotifier();
@@ -198,41 +77,51 @@ void PluginGUI::init()
 	config = new Config();
 	config->load();
 
-	window = new DGWindow(native_window, msghandler, *config, settings);
+	window = new DGWindow(native_window, *config, settings);
+
+
+	CONNECT(this, settings_notifier.drumkit_file,
+	        window->lineedit, &LineEdit::setText);
+	CONNECT(this, settings_notifier.drumkit_load_status,
+	        window, &DGWindow::setDrumKitLoadStatus);
 
-	CONNECT(this, enable_velocity_modifier_notifier,
+	CONNECT(this, settings_notifier.midimap_file,
+	        window->lineedit2, &LineEdit::setText);
+	CONNECT(this, settings_notifier.midimap_load_status,
+	        window, &DGWindow::setMidiMapLoadStatus);
+
+	CONNECT(this, settings_notifier.enable_velocity_modifier,
 	        window->velocityCheck, &CheckBox::setChecked);
 
-	CONNECT(this, velocity_modifier_falloff_notifier,
+	CONNECT(this, settings_notifier.velocity_modifier_falloff,
 	        window->falloffKnob, &Knob::setValue);
-	CONNECT(this, velocity_modifier_weight_notifier,
+	CONNECT(this, settings_notifier.velocity_modifier_weight,
 	        window->attackKnob, &Knob::setValue);
 
 
-	//CONNECT(this, enable_velocity_randomiser_notifier,
-	//        window->velocityCheck, &CheckBox::setChecked);
-	//CONNECT(this, velocity_randomiser_weight_notifier,
-	//        window->velocityCheck, &CheckBox::setChecked);
+	// TODO:
+	//CONNECT(this, settings_notifier.enable_velocity_randomiser,
+	//        window->, &CheckBox::setChecked);
+	//CONNECT(this, settings_notifier.velocity_randomiser_weight,
+	//        window->, &Knob::setValue);
+
+	//CONNECT(this, settings_notifier.samplerate,
+	//        window->, &Knob::setValue);
 
-	//CONNECT(this, samplerate_notifier,
-	//        window->velocityCheck, &CheckBox::setChecked);
+	//CONNECT(this, settings_notifier.enable_resampling,
+	//        window->, &CheckBox::setChecked);
 
-	//CONNECT(this, enable_resampling_notifier,
-	//        window->velocityCheck, &CheckBox::setChecked);
+	CONNECT(this, settings_notifier.number_of_files,
+	        window->drumkitFileProgress, &ProgressBar::setTotal);
 
-	CONNECT(this, drumkit_file_progress_notifier,
-	        window->drumkitFileProgress, &ProgressBar::setProgress);
+	CONNECT(this, settings_notifier.number_of_files_loaded,
+	        window->drumkitFileProgress, &ProgressBar::setValue);
 
 	auto eventHandler = window->eventHandler();
 	CONNECT(eventHandler, closeNotifier, this, &PluginGUI::closeEventHandler);
 
 	window->show();
 
-	{ // Request all engine settings
-		EngineSettingsMessage *msg = new EngineSettingsMessage();
-		msghandler.sendMessage(MSGRCV_ENGINE, msg);
-	}
-
 	initialised = true;
 }
 
diff --git a/plugingui/plugingui.h b/plugingui/plugingui.h
index ca31c41..04b0a29 100644
--- a/plugingui/plugingui.h
+++ b/plugingui/plugingui.h
@@ -26,24 +26,20 @@
  */
 #pragma once
 
+#include <settings.h>
+#include <notifier.h>
+
 #include "dgwindow.h"
 #include "eventhandler.h"
-
 #include "pluginconfig.h"
 
-#include <settings.h>
-
-#include "messagereceiver.h"
-#include "notifier.h"
-
 namespace GUI {
 
 class PluginGUI
-	: public MessageReceiver
-	, public Listener
+	: public Listener
 {
 public:
-	PluginGUI(void* native_window = nullptr);
+	PluginGUI(Settings& settings, void* native_window = nullptr);
 	virtual ~PluginGUI();
 
 	//! Process all events and messages in queue
@@ -56,9 +52,6 @@ public:
 	void show();
 	void hide();
 
-
-	void handleMessage(Message* msg);
-
 	DGWindow* window{nullptr};
 	EventHandler* eventhandler{nullptr};
 
@@ -66,21 +59,6 @@ public:
 
 	Notifier<> closeNotifier;
 
-	// Setting notifiers:
-	Notifier<bool> enable_velocity_modifier_notifier;
-	Notifier<float> velocity_modifier_falloff_notifier;
-	Notifier<float> velocity_modifier_weight_notifier;
-
-	Notifier<bool> enable_velocity_randomiser_notifier;
-	Notifier<float> velocity_randomiser_weight_notifier;
-
-	Notifier<double> samplerate_notifier;
-
-	Notifier<bool> enable_resampling_notifier;
-
-	Notifier<float> drumkit_file_progress_notifier;
-	//Notifier<std::string> current_file_notifier;
-
 	// Support old interface a little while longer..
 	void setWindowClosedCallback(void (*handler)(void*), void* ptr);
 
@@ -97,8 +75,8 @@ private:
 	void (*windowClosedHandler)(void *){nullptr};
 	void *windowClosedPtr{nullptr};
 
-	Settings settings;
-	SettingsGetter getter{settings};
+	Settings& settings;
+	SettingsNotifier settings_notifier{settings};
 };
 
 } // GUI::
diff --git a/plugingui/progressbar.cc b/plugingui/progressbar.cc
index 932f17c..f934664 100644
--- a/plugingui/progressbar.cc
+++ b/plugingui/progressbar.cc
@@ -26,6 +26,8 @@
  */
 #include "progressbar.h"
 
+#include <iostream>
+
 namespace GUI {
 
 ProgressBar::ProgressBar(Widget *parent)
@@ -46,9 +48,6 @@ ProgressBar::ProgressBar(Widget *parent)
 	bar_green.left    = new Image(":progress_front_green_l.png");
 	bar_green.right   = new Image(":progress_front_green_r.png");
 	bar_green.center  = new Image(":progress_front_green_c.png");
-
-	state = ProgressBarState::Blue;
-	_progress = .5;
 }
 
 ProgressBar::~ProgressBar()
@@ -79,22 +78,31 @@ void ProgressBar::setState(ProgressBarState state)
 	}
 }
 
-float ProgressBar::progress()
+void ProgressBar::setTotal(int total)
 {
-	return _progress;
+	if(this->total != total)
+	{
+		this->total = total;
+		repaintEvent(nullptr);
+	}
 }
 
-void ProgressBar::setProgress(float progress)
+void ProgressBar::setValue(int value)
 {
-	_progress = progress;
-	repaintEvent(nullptr);
+	if(this->value != value)
+	{
+		this->value = value;
+		repaintEvent(nullptr);
+	}
 }
 
 void ProgressBar::repaintEvent(RepaintEvent* repaintEvent)
 {
 	Painter p(*this);
 
-	int max = width() * _progress;
+	float progress = (float)value / (float)total;
+
+	int max = width() * progress;
 
 	p.clear();
 
diff --git a/plugingui/progressbar.h b/plugingui/progressbar.h
index d5f6c61..d48a8b5 100644
--- a/plugingui/progressbar.h
+++ b/plugingui/progressbar.h
@@ -46,8 +46,8 @@ public:
 	ProgressBar(Widget *parent);
 	~ProgressBar();
 
-	float progress();
-	void setProgress(float progress);
+	void setTotal(int total);
+	void setValue(int value);
 
 	void setState(ProgressBarState state);
 
@@ -56,7 +56,7 @@ protected:
 	virtual void repaintEvent(RepaintEvent* repaintEvent) override;
 
 private:
-	ProgressBarState state;
+	ProgressBarState state{ProgressBarState::Blue};
 
 	Painter::Bar bar_bg;
 
@@ -64,7 +64,8 @@ private:
 	Painter::Bar bar_blue;
 	Painter::Bar bar_red;
 
-	float _progress;
+	int total{0};
+	int value{0};
 };
 
 } // GUI::
diff --git a/plugingui/testmain.cc b/plugingui/testmain.cc
index b3a0d8d..84d813d 100644
--- a/plugingui/testmain.cc
+++ b/plugingui/testmain.cc
@@ -33,13 +33,10 @@
 
 #include <hugin.hpp>
 
-// Dummy Engine class.
-class Engine : public MessageHandler {
-public:
-	void handleMessage(Message *msg) {}
-};
+#include <notifier.h>
+#include <settings.h>
 
-class TestMain : public GUI::Listener {
+class TestMain : public Listener {
 public:
 	TestMain()
 	{
@@ -67,7 +64,8 @@ public:
 
 	bool running = true;
 
-	GUI::PluginGUI gui;
+	Settings settings;
+	GUI::PluginGUI gui{settings};
 };
 
 int main()
diff --git a/src/Makefile.am b/src/Makefile.am
index 9dd6c29..4d167af 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -23,13 +23,11 @@ EXTRA_DIST = \
 	instrument.h \
 	instrumentparser.h \
 	memchecker.h \
-	message.h \
-	messagehandler.h \
-	messagereceiver.h \
 	midimapparser.h \
 	midimapper.h \
 	mutex.h \
 	nolocale.h \
+	notifier.h \
 	path.h \
 	powerlist.h \
 	rangemap.h \
@@ -62,8 +60,6 @@ EXTRA_DIST = \
 	instrument.cc \
 	instrumentparser.cc \
 	memchecker.cc \
-	messagehandler.cc \
-	messagereceiver.cc \
 	midimapparser.cc \
 	midimapper.cc \
 	mutex.cc \
diff --git a/src/Makefile.am.drumgizmo b/src/Makefile.am.drumgizmo
index e707fe2..6fddded 100644
--- a/src/Makefile.am.drumgizmo
+++ b/src/Makefile.am.drumgizmo
@@ -20,8 +20,6 @@ DRUMGIZMO_SOURCES = \
 	$(top_srcdir)/src/instrument.cc \
 	$(top_srcdir)/src/instrumentparser.cc \
 	$(top_srcdir)/src/memchecker.cc \
-	$(top_srcdir)/src/messagehandler.cc \
-	$(top_srcdir)/src/messagereceiver.cc \
 	$(top_srcdir)/src/midimapparser.cc \
 	$(top_srcdir)/src/midimapper.cc \
 	$(top_srcdir)/src/mutex.cc \
diff --git a/src/atomic.h b/src/atomic.h
index e0b80b1..95a5e9d 100644
--- a/src/atomic.h
+++ b/src/atomic.h
@@ -116,7 +116,67 @@ public:
 		return data;
 	}
 
+	bool operator==(const T& other) const
+	{
+		std::lock_guard<std::mutex> lock{mutex};
+		return other == data;
+	}
+
+	bool operator!=(const T& other) const
+	{
+		std::lock_guard<std::mutex> lock{mutex};
+		return !(other == data);
+	}
+
+	bool operator==(const Atomic<T>& other) const
+	{
+		std::lock_guard<std::mutex> lock{mutex};
+		return other.load() == data;
+	}
+
+	bool operator!=(const Atomic<T>& other) const
+	{
+		std::lock_guard<std::mutex> lock{mutex};
+		return !(other.load() == data);
+	}
+
 private:
 	T data;
 	mutable std::mutex mutex;
 };
+
+//! Getter utility class.
+template <typename T> class SettingRef
+{
+public:
+	SettingRef(Atomic<T>& value)
+		: value(value)
+	{
+		// string isn't lock free either
+		assert((std::is_same<T, std::string>::value || value.is_lock_free()));
+	}
+
+	bool hasChanged()
+	{
+		T tmp = cache;
+		cache.exchange(value);
+
+		if(firstAccess)
+		{
+			firstAccess = false;
+			return true;
+		}
+
+		return cache != tmp;
+	}
+
+	T getValue() const
+	{
+		return cache;
+	}
+
+private:
+	bool firstAccess{true};
+	Atomic<T>& value;
+	Atomic<T> cache;
+};
diff --git a/src/drumgizmo.cc b/src/drumgizmo.cc
index f769f4e..aa6be23 100644
--- a/src/drumgizmo.cc
+++ b/src/drumgizmo.cc
@@ -38,6 +38,7 @@
 #include <hugin.hpp>
 
 #include <config.h>
+#include <memory>
 
 #include "drumkitparser.h"
 #include "audioinputenginemidi.h"
@@ -47,8 +48,7 @@
 
 DrumGizmo::DrumGizmo(Settings& settings,
                      AudioOutputEngine *o, AudioInputEngine *i)
-	: MessageReceiver(MSGRCV_ENGINE)
-	, loader(settings)
+	: loader(settings)
 	, oe(o)
 	, ie(i)
 	, framesize(0)
@@ -69,9 +69,12 @@ DrumGizmo::~DrumGizmo()
 
 bool DrumGizmo::loadkit(std::string file)
 {
+	settings.drumkit_load_status.store(LoadStatus::Idle);
+
 	if(file == "")
 	{
-		return 1;
+		settings.drumkit_load_status.store(LoadStatus::Error);
+		return false;
 	}
 
 	DEBUG(drumgizmo, "loadkit(%s)\n", file.c_str());
@@ -82,20 +85,24 @@ bool DrumGizmo::loadkit(std::string file)
 	// Delete all Channels, Instruments, Samples and AudioFiles.
 	kit.clear();
 
+	settings.drumkit_load_status.store(LoadStatus::Loading);
+
 	DrumKitParser parser(settings, kit);
 	if(parser.parseFile(file))
 	{
 		ERR(drumgizmo, "Drumkit parser failed: %s\n", file.c_str());
+		settings.drumkit_load_status.store(LoadStatus::Error);
 		return false;
 	}
 
-	// Check if there is enough free RAM to load the drumkit.
-	if(!memchecker.enoughFreeMemory(kit))
-	{
-		printf("WARNING: "
-		       "There doesn't seem to be enough RAM available to load the kit.\n"
-		       "Trying to load it anyway...\n");
-	}
+	// TODO: Re-introduce when the code has been moved to the loader thread.
+	//// Check if there is enough free RAM to load the drumkit.
+	//if(!memchecker.enoughFreeMemory(kit))
+	//{
+	//	printf("WARNING: "
+	//	       "There doesn't seem to be enough RAM available to load the kit.\n"
+	//	       "Trying to load it anyway...\n");
+	//}
 
 	loader.loadKit(&kit);
 
@@ -126,79 +133,6 @@ bool DrumGizmo::init()
 	return true;
 }
 
-void DrumGizmo::handleMessage(Message *msg)
-{
-	DEBUG(msg, "got message.");
-	switch(msg->type()) {
-	case Message::LoadDrumKit:
-		{
-			DEBUG(msg, "got LoadDrumKitMessage message.");
-			LoadDrumKitMessage *m = (LoadDrumKitMessage*)msg;
-			loadkit(m->drumkitfile);
-			//init(true);
-		}
-		break;
-	case Message::LoadMidimap:
-		DEBUG(msg, "got LoadMidimapMessage message.");
-		if(!ie->isMidiEngine())
-		{
-			break;
-		}
-		{
-			AudioInputEngineMidi *aim = (AudioInputEngineMidi*)ie;
-			LoadMidimapMessage *m = (LoadMidimapMessage*)msg;
-			bool ret = aim->loadMidiMap(m->midimapfile, kit.instruments);
-
-			LoadStatusMessageMidimap *ls = new LoadStatusMessageMidimap();
-			ls->success = ret;
-			msghandler.sendMessage(MSGRCV_UI, ls);
-		}
-		break;
-	case Message::EngineSettingsMessage:
-		{
-			bool mmap_loaded = false;
-			std::string mmapfile;
-			if(ie->isMidiEngine())
-			{
-				AudioInputEngineMidi *aim = (AudioInputEngineMidi*)ie;
-				mmapfile = aim->getMidimapFile();
-				mmap_loaded = aim->isValid();
-			}
-
-			EngineSettingsMessage *msg = new EngineSettingsMessage();
-			msg->midimapfile = mmapfile;
-			msg->midimap_loaded = mmap_loaded;
-			msg->drumkitfile = kit.getFile();
-			msg->drumkit_loaded = loader.isDone();
-			msg->enable_velocity_modifier = settings.enable_velocity_modifier.load();
-			msg->velocity_modifier_falloff = settings.velocity_modifier_falloff.load();
-			msg->velocity_modifier_weight = settings.velocity_modifier_weight.load();
-			msg->enable_velocity_randomiser = settings.enable_velocity_randomiser.load();
-			msg->velocity_randomiser_weight = settings.velocity_randomiser_weight.load();
-			msghandler.sendMessage(MSGRCV_UI, msg);
-		}
-		break;
-	case Message::ChangeSettingMessage:
-		{
-			ChangeSettingMessage *ch = (ChangeSettingMessage*)msg;
-			switch(ch->name) {
-			case ChangeSettingMessage::enable_velocity_modifier:
-				settings.enable_velocity_modifier.store(ch->value);
-				break;
-			case ChangeSettingMessage::velocity_modifier_weight:
-				settings.velocity_modifier_weight.store(ch->value);
-				break;
-			case ChangeSettingMessage::velocity_modifier_falloff:
-				settings.velocity_modifier_falloff.store(ch->value);
-				break;
-			}
-		}
-		break;
-	default:
-		break;
-	}
-}
-
 void DrumGizmo::setFrameSize(size_t framesize)
 {
 	// If we are resampling override the frame size.
@@ -260,8 +194,31 @@ bool DrumGizmo::run(size_t pos, sample_t *samples, size_t nsamples)
 {
 	setFrameSize(nsamples);
 
-	// Handle engine messages, at most one in each iteration:
-	handleMessages(1);
+	// TODO: Move this to DrumKitLoader thread.
+	if(getter.drumkit_file.hasChanged())
+	{
+		loadkit(getter.drumkit_file.getValue());
+	}
+
+	// TODO: Move this to DrumKitLoader thread.
+	if(getter.midimap_file.hasChanged())
+	{
+		auto ie_midi = dynamic_cast<AudioInputEngineMidi*>(ie);
+		if(ie_midi)
+		{
+			settings.midimap_load_status.store(LoadStatus::Loading);
+			bool ret = ie_midi->loadMidiMap(getter.midimap_file.getValue(),
+			                                kit.instruments);
+			if(ret)
+			{
+				settings.midimap_load_status.store(LoadStatus::Done);
+			}
+			else
+			{
+				settings.midimap_load_status.store(LoadStatus::Error);
+			}
+		}
+	}
 
 	ie->pre();
 	oe->pre(nsamples);
@@ -712,8 +669,8 @@ bool DrumGizmo::setConfigString(std::string cfg)
 	ConfigParser p;
 	if(p.parseString(cfg))
 	{
-	 ERR(drumgizmo, "Config parse error.\n");
-	 return false;
+		ERR(drumgizmo, "Config parse error.\n");
+		return false;
 	}
 
 	if(p.value("enable_velocity_modifier") != "")
@@ -747,27 +704,15 @@ bool DrumGizmo::setConfigString(std::string cfg)
 	}
 
 	std::string newkit = p.value("drumkitfile");
-	if(newkit != "" && kit.getFile() != newkit)
+	if(newkit != "")
 	{
-		/*
-		  if(!loadkit(p.values["drumkitfile"]))
-		  {
-		  return false;
-		  }
-		  init(true);
-		*/
-		LoadDrumKitMessage *msg = new LoadDrumKitMessage();
-		msg->drumkitfile = newkit;
-		msghandler.sendMessage(MSGRCV_ENGINE, msg);
+		settings.drumkit_file.store(newkit);
 	}
 
 	std::string newmidimap = p.value("midimapfile");
 	if(newmidimap != "")
 	{
-		//midimapfile = newmidimap;
-		LoadMidimapMessage *msg = new LoadMidimapMessage();
-		msg->midimapfile = newmidimap;
-		msghandler.sendMessage(MSGRCV_ENGINE, msg);
+		settings.midimap_file.store(newmidimap);
 	}
 
 	return true;
diff --git a/src/drumgizmo.h b/src/drumgizmo.h
index 63348da..7af5dbb 100644
--- a/src/drumgizmo.h
+++ b/src/drumgizmo.h
@@ -31,25 +31,15 @@
 
 #include "audiooutputengine.h"
 #include "audioinputengine.h"
-
 #include "events.h"
 #include "audiofile.h"
 #include "drumkit.h"
 #include "memchecker.h"
-
 #include "drumkitloader.h"
 #include "audiocache.h"
-
 #include "mutex.h"
-
-#include "message.h"
-
-#include "messagereceiver.h"
-
 #include "chresampler.h"
-
 #include "configfile.h"
-
 #include "settings.h"
 
 #define MAX_NUM_CHANNELS 64
@@ -57,7 +47,6 @@
 #define RESAMPLER_INPUT_BUFFER 64
 
 class DrumGizmo
-	: public MessageReceiver
 {
 public:
 	DrumGizmo(Settings& settings,
@@ -77,8 +66,6 @@ public:
 	std::string configString();
 	bool setConfigString(std::string cfg);
 
-	void handleMessage(Message *msg);
-
 	int samplerate();
 	void setSamplerate(int samplerate);
 
@@ -112,4 +99,5 @@ protected:
 
 	std::vector<event_t> events;
 	Settings& settings;
+	SettingsGetter getter{settings};
 };
diff --git a/src/drumkitloader.cc b/src/drumkitloader.cc
index 3cb4b68..f9e45db 100644
--- a/src/drumkitloader.cc
+++ b/src/drumkitloader.cc
@@ -184,18 +184,14 @@ void DrumKitLoader::thread_main()
 			audiofile->load(preload_size);
 		}
 
-		loaded++;
+		++loaded;
 
-		if(loaded % fraction == 0 || loaded == total_num_audiofiles)
+		settings.number_of_files.store(total_num_audiofiles);
+		settings.number_of_files_loaded.store(loaded);
+
+		if(total_num_audiofiles == loaded)
 		{
-			//LoadStatusMessage *ls = new LoadStatusMessage();
-			//ls->number_of_files = total_num_audiofiles;
-			//ls->numer_of_files_loaded = loaded;
-			//ls->current_file = filename;
-			//msghandler.sendMessage(MSGRCV_UI, ls);
-			settings.number_of_files.store(total_num_audiofiles);
-			settings.number_of_files_loaded.store(loaded);
-			//settings.current_file.store(filename);
+			settings.drumkit_load_status.store(LoadStatus::Done);
 		}
 	}
 
diff --git a/src/drumkitparser.cc b/src/drumkitparser.cc
index 221e921..048a05b 100644
--- a/src/drumkitparser.cc
+++ b/src/drumkitparser.cc
@@ -34,7 +34,7 @@
 #include "path.h"
 #include "drumgizmo.h"
 
-DrumKitParser::DrumKitParser(Settings& setting, DrumKit& k)
+DrumKitParser::DrumKitParser(Settings& settings, DrumKit& k)
 	: kit(k)
 	, refs(REFSFILE)
 	, settings(settings)
diff --git a/src/instrument.cc b/src/instrument.cc
index f187de0..cc052e9 100644
--- a/src/instrument.cc
+++ b/src/instrument.cc
@@ -42,7 +42,7 @@ Instrument::Instrument(Settings& settings)
 
 Instrument::~Instrument()
 {
-	magic = NULL;
+	magic = nullptr;
 
 	DEBUG(instrument, "delete %p\n", this);
 	std::vector<AudioFile*>::iterator i = audiofiles.begin();
@@ -60,8 +60,6 @@ bool Instrument::isValid() const
 
 Sample* Instrument::sample(level_t level, size_t pos)
 {
-	Sample *sample = NULL;
-
 	// Read out all values from settings.
 	auto enable_velocity_randomiser = settings.enable_velocity_randomiser.load();
 	auto velocity_randomiser_weight = settings.velocity_randomiser_weight.load();
@@ -70,6 +68,8 @@ Sample* Instrument::sample(level_t level, size_t pos)
 	auto enable_velocity_modifier = settings.enable_velocity_modifier.load();
 	auto velocity_modifier_weight = settings.velocity_modifier_weight.load();
 
+	Sample *sample = nullptr;
+
 	if(enable_velocity_modifier == false)
 	{
 		mod = 1.0;
@@ -78,14 +78,13 @@ Sample* Instrument::sample(level_t level, size_t pos)
 
 	if(enable_velocity_randomiser)
 	{
-		float r = rand.floatInRange(-0.5f, 0.5f);
-		r *= velocity_randomiser_weight * 2; // ex. random number [-0.1;0.1]
+		float r = rand.floatInRange(-1.0 * velocity_randomiser_weight,
+		                            velocity_randomiser_weight);
 		level += r;
 		if(level > 1.0)
 		{
 			level = 1.0;
 		}
-
 		if(level < 0.0)
 		{
 			level = 0.0;
@@ -94,8 +93,7 @@ Sample* Instrument::sample(level_t level, size_t pos)
 
 	if(enable_velocity_modifier)
 	{
-		mod += (pos - lastpos) /
-			(samplerate * velocity_modifier_falloff);
+		mod += (pos - lastpos) / (samplerate * velocity_modifier_falloff);
 		if(mod > 1.0)
 		{
 			mod = 1.0;
@@ -113,11 +111,10 @@ Sample* Instrument::sample(level_t level, size_t pos)
 		std::vector<Sample*> s = samples.get(level * mod);
 		if(s.size() == 0)
 		{
-			return NULL;
+			return nullptr;
 		}
 
-		//size_t idx = ::rand()%(s.size());
-		sample = rand.choose<Sample*>(s);
+		sample = rand.choose(s);
 	}
 
 	if(enable_velocity_modifier)
diff --git a/src/message.h b/src/message.h
deleted file mode 100644
index 71d0da6..0000000
--- a/src/message.h
+++ /dev/null
@@ -1,121 +0,0 @@
-/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
-/***************************************************************************
- *            message.h
- *
- *  Wed Mar 20 15:50:57 CET 2013
- *  Copyright 2013 Bent Bisballe Nyeng
- *  deva@aasimon.org
- ****************************************************************************/
-
-/*
- *  This file is part of DrumGizmo.
- *
- *  DrumGizmo is free software; you can redistribute it and/or modify
- *  it under the terms of the GNU Lesser General Public License as published by
- *  the Free Software Foundation; either version 3 of the License, or
- *  (at your option) any later version.
- *
- *  DrumGizmo is distributed in the hope that it will be useful,
- *  but WITHOUT ANY WARRANTY; without even the implied warranty of
- *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- *  GNU Lesser General Public License for more details.
- *
- *  You should have received a copy of the GNU Lesser General Public License
- *  along with DrumGizmo; if not, write to the Free Software
- *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
- */
-#ifndef __DRUMGIZMO_MESSAGE_H__
-#define __DRUMGIZMO_MESSAGE_H__
-
-#include <string>
-
-class MessageHandler;
-
-class Message {
-public:
-  typedef enum {
-    // Engine -> GUI Messages:
-    LoadStatus, // Signal GUI the current load status.
-    LoadStatusMidimap, // Signal GUI the current load status of the midimap.
-
-    // GUI -> Engine, Engine -> Engine Messages:
-    LoadDrumKit, // Signal engine to load drumkit.
-    LoadMidimap, // Signal engine to load midimap.
-    EngineSettingsMessage, // Request or receive engine settings.
-    ChangeSettingMessage, // Update named setting in engine.
-  } type_t;
-
-  typedef enum {
-    NormalProcessing, // Just add to the queue
-    FilterMultiple, // Ignore top message if it has the same type.
-    // SyncWait, // Block the send call until the message has been handled by the receiver.
-  } processing_mode_t;
-
-  virtual ~Message() {}
-  virtual type_t type() = 0;
-  virtual processing_mode_t processing_mode() { return NormalProcessing; }
-};
-
-class LoadStatusMessage : public Message {
-public:
-  type_t type() { return Message::LoadStatus; }
-  processing_mode_t processing_mode() { return FilterMultiple; }
-  unsigned int number_of_files;
-  unsigned int numer_of_files_loaded;
-  std::string current_file;
-};
-
-class LoadStatusMessageMidimap : public Message {
-public:
-  type_t type() { return Message::LoadStatusMidimap; }
-  bool success;
-};
-
-class LoadDrumKitMessage : public Message {
-public:
-  type_t type() { return Message::LoadDrumKit; }
-  std::string drumkitfile;
-};
-
-class LoadMidimapMessage : public Message {
-public:
-  type_t type() { return Message::LoadMidimap; }
-  std::string midimapfile;
-};
-
-class EngineSettingsMessage : public Message {
-public:
-  type_t type() { return Message::EngineSettingsMessage; }
-  std::string midimapfile;
-  bool midimap_loaded;
-
-  std::string drumkitfile;
-  bool drumkit_loaded;
-
-  float enable_velocity_modifier;
-  float velocity_modifier_falloff;
-  float velocity_modifier_weight;
-  float enable_velocity_randomiser;
-  float velocity_randomiser_weight;
-};
-
-class ChangeSettingMessage : public Message {
-public:
-  typedef enum {
-    enable_velocity_modifier,
-    velocity_modifier_weight,
-    velocity_modifier_falloff,
-  } setting_name_t;
-
-  ChangeSettingMessage(setting_name_t n, float v) {
-    name = n;
-    value = v;
-  }
-
-  type_t type() { return Message::ChangeSettingMessage; }
-
-  setting_name_t name;
-  float value;
-};
-
-#endif/*__DRUMGIZMO_MESSAGE_H__*/
diff --git a/src/messagehandler.cc b/src/messagehandler.cc
deleted file mode 100644
index 7a0c7ea..0000000
--- a/src/messagehandler.cc
+++ /dev/null
@@ -1,89 +0,0 @@
-/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
-/***************************************************************************
- *            messagehandler.cc
- *
- *  Fri Jun 14 20:30:43 CEST 2013
- *  Copyright 2013 Bent Bisballe Nyeng
- *  deva@aasimon.org
- ****************************************************************************/
-
-/*
- *  This file is part of DrumGizmo.
- *
- *  DrumGizmo is free software; you can redistribute it and/or modify
- *  it under the terms of the GNU Lesser General Public License as published by
- *  the Free Software Foundation; either version 3 of the License, or
- *  (at your option) any later version.
- *
- *  DrumGizmo is distributed in the hope that it will be useful,
- *  but WITHOUT ANY WARRANTY; without even the implied warranty of
- *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- *  GNU Lesser General Public License for more details.
- *
- *  You should have received a copy of the GNU Lesser General Public License
- *  along with DrumGizmo; if not, write to the Free Software
- *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
- */
-#include "messagehandler.h"
-
-#include <hugin.hpp>
-
-#include "messagereceiver.h"
-
-// Global messagehandler:
-MessageHandler msghandler;
-
-MessageHandler::MessageHandler()
-{
-}
-
-void MessageHandler::addReceiver(message_receiver_id_t id,
-                                 MessageReceiver *receiver)
-{
-  MutexAutolock l(mutex);
-
-  receivers[id] = receiver;
-}
-
-void MessageHandler::removeReceiver(MessageReceiver *receiver)
-{
-  MutexAutolock l(mutex);
-
-  std::map<message_receiver_id_t, MessageReceiver *>::iterator i =
-    receivers.begin();
-  while(i != receivers.end()) {
-    if(i->second == receiver) {
-      receivers.erase(i);
-      break;
-    }
-    i++;
-  }
-}
-
-bool MessageHandler::sendMessage(message_receiver_id_t id, Message* msg)
-{
-  MutexAutolock l(mutex);
-
-  if(receivers.find(id) == receivers.end()) {
-    //WARN(msghandler, "Could not find id %d\n", id);
-    delete msg;
-    return false;
-  }
-
-  //DEBUG(msghandler, "Sending message to id %d\n", id);
-
-  MessageReceiver *receiver = receivers[id];
-  /* // This code causes sporadic segfaults on windows.
-  if(msg->processing_mode() == Message::FilterMultiple) {
-    Message *pmsg;
-    MutexAutolock lock(receiver->message_mutex); // Make peek/receive atomic.
-    while( (pmsg = receiver->peekMessage()) != NULL) {
-      if(pmsg->type() != msg->type()) break;
-      // Remove all old messages with same type.
-      delete receiver->receiveMessage();
-    }
-  }
-  */
-  receiver->sendMessage(msg);
-  return true;
-}
diff --git a/src/messagehandler.h b/src/messagehandler.h
deleted file mode 100644
index 2b6c40e..0000000
--- a/src/messagehandler.h
+++ /dev/null
@@ -1,66 +0,0 @@
-/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
-/***************************************************************************
- *            messagehandler.h
- *
- *  Fri Jun 14 20:30:43 CEST 2013
- *  Copyright 2013 Bent Bisballe Nyeng
- *  deva@aasimon.org
- ****************************************************************************/
-
-/*
- *  This file is part of DrumGizmo.
- *
- *  DrumGizmo is free software; you can redistribute it and/or modify
- *  it under the terms of the GNU Lesser General Public License as published by
- *  the Free Software Foundation; either version 3 of the License, or
- *  (at your option) any later version.
- *
- *  DrumGizmo is distributed in the hope that it will be useful,
- *  but WITHOUT ANY WARRANTY; without even the implied warranty of
- *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- *  GNU Lesser General Public License for more details.
- *
- *  You should have received a copy of the GNU Lesser General Public License
- *  along with DrumGizmo; if not, write to the Free Software
- *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
- */
-#ifndef __DRUMGIZMO_MESSAGEHANDLER_H__
-#define __DRUMGIZMO_MESSAGEHANDLER_H__
-
-#include <map>
-
-#include "message.h"
-#include "mutex.h"
-
-typedef enum {
-  MSGRCV_ENGINE = 1,
-  MSGRCV_UI = 2,
-  MSGRCV_LOADER = 3,
-} message_receiver_id_t;
-
-class MessageReceiver;
-
-class MessageHandler {
-public:
-  MessageHandler();
-
-  void addReceiver(message_receiver_id_t id, MessageReceiver *receiver);
-  void removeReceiver(MessageReceiver *receiver);
-
-  /**
-   * Send Message to receiver with specified id.
-   * @return Return true if id is registered. Return false if id is not
-   * currently registered.
-   */
-  bool sendMessage(message_receiver_id_t id, Message* msg);
-
-private:
-  std::map<message_receiver_id_t, MessageReceiver *> receivers;
-
-  Mutex mutex;
-};
-
-// Global MessageHandler;
-extern MessageHandler msghandler;
-
-#endif/*__DRUMGIZMO_MESSAGEHANDLER_H__*/
diff --git a/src/messagereceiver.cc b/src/messagereceiver.cc
deleted file mode 100644
index 590c98a..0000000
--- a/src/messagereceiver.cc
+++ /dev/null
@@ -1,78 +0,0 @@
-/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
-/***************************************************************************
- *            messagereceiver.cc
- *
- *  Sun Jun 16 12:09:06 CEST 2013
- *  Copyright 2013 Bent Bisballe Nyeng
- *  deva@aasimon.org
- ****************************************************************************/
-
-/*
- *  This file is part of DrumGizmo.
- *
- *  DrumGizmo is free software; you can redistribute it and/or modify
- *  it under the terms of the GNU Lesser General Public License as published by
- *  the Free Software Foundation; either version 3 of the License, or
- *  (at your option) any later version.
- *
- *  DrumGizmo is distributed in the hope that it will be useful,
- *  but WITHOUT ANY WARRANTY; without even the implied warranty of
- *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- *  GNU Lesser General Public License for more details.
- *
- *  You should have received a copy of the GNU Lesser General Public License
- *  along with DrumGizmo; if not, write to the Free Software
- *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
- */
-#include "messagereceiver.h"
-
-#include <hugin.hpp>
-
-MessageReceiver::MessageReceiver(message_receiver_id_t id)
-{
-  msghandler.addReceiver(id, this);
-}
-
-MessageReceiver::~MessageReceiver()
-{
-  msghandler.removeReceiver(this);
-}
-
-void MessageReceiver::sendMessage(Message *msg)
-{
-  MutexAutolock l(message_mutex);
-
-  message_queue.push_back(msg);
-}
-
-Message *MessageReceiver::receiveMessage()
-{
-  Message *msg = NULL;
-  if(message_queue.size()) {
-    msg = message_queue.front();
-    message_queue.pop_front();
-  }
-  return msg;
-}
-
-Message *MessageReceiver::peekMessage()
-{
-  Message *msg = NULL;
-  if(message_queue.size()) {
-    msg = message_queue.front();
-  }
-  return msg;
-}
-
-void MessageReceiver::handleMessages(size_t max)
-{
-  MutexAutolock l(message_mutex);
-  bool process_all = false;
-  if(max == 0) process_all = true;
-
-  while((process_all || max--) && peekMessage()) {
-    Message *msg = receiveMessage();
-    handleMessage(msg);
-    delete msg;
-  }
-}
diff --git a/src/messagereceiver.h b/src/messagereceiver.h
deleted file mode 100644
index c1a8e60..0000000
--- a/src/messagereceiver.h
+++ /dev/null
@@ -1,75 +0,0 @@
-/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
-/***************************************************************************
- *            messagereceiver.h
- *
- *  Sun Jun 16 12:09:06 CEST 2013
- *  Copyright 2013 Bent Bisballe Nyeng
- *  deva@aasimon.org
- ****************************************************************************/
-
-/*
- *  This file is part of DrumGizmo.
- *
- *  DrumGizmo is free software; you can redistribute it and/or modify
- *  it under the terms of the GNU Lesser General Public License as published by
- *  the Free Software Foundation; either version 3 of the License, or
- *  (at your option) any later version.
- *
- *  DrumGizmo is distributed in the hope that it will be useful,
- *  but WITHOUT ANY WARRANTY; without even the implied warranty of
- *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- *  GNU Lesser General Public License for more details.
- *
- *  You should have received a copy of the GNU Lesser General Public License
- *  along with DrumGizmo; if not, write to the Free Software
- *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
- */
-#ifndef __DRUMGIZMO_MESSAGERECEIVER_H__
-#define __DRUMGIZMO_MESSAGERECEIVER_H__
-
-#include <list>
-
-#include "mutex.h"
-#include "message.h"
-#include "messagehandler.h"
-
-class MessageReceiver {
-  friend class MessageHandler;
-public:
-  MessageReceiver(message_receiver_id_t id);
-  ~MessageReceiver();
-
-  /**
-   * Receive message from the message queue.
-   */
-  Message *receiveMessage();
-
-  /**
-   * Receive message from the message queue without removing it.
-   */
-  Message *peekMessage();
-
-  /**
-   * Add a message to the message queue.
-   */
-  void sendMessage(Message *msg);
-
-  /**
-   * Handle messages from the event queue.
-   * @param max_number_of_events the maximum number of events to be handled in
-   * this call. 0 means all.
-   */
-  void handleMessages(size_t max_number_of_events = 0);
-
-  /**
-   * Handler to be implemented in child classes.
-   * Handles a single event.
-   */
-  virtual void handleMessage(Message *msg) = 0;
-
-private:
-  Mutex message_mutex;
-  std::list<Message *> message_queue;
-};
-
-#endif/*__DRUMGIZMO_MESSAGERECEIVER_H__*/
diff --git a/plugingui/notifier.h b/src/notifier.h
index 9e9f6eb..ff59741 100644
--- a/plugingui/notifier.h
+++ b/src/notifier.h
@@ -72,7 +72,7 @@ namespace aux
 };
 
 
-namespace GUI {
+//namespace GUI {
 
 class Listener;
 class NotifierBase {
@@ -158,6 +158,6 @@ private:
 
 };
 
-} // GUI::
+//} // GUI::
 
 #define CONNECT(SRC, SIG, TAR, SLO) (SRC)->SIG.connect(TAR, SLO)
diff --git a/src/settings.h b/src/settings.h
index b132c1b..c79e4e5 100644
--- a/src/settings.h
+++ b/src/settings.h
@@ -31,10 +31,25 @@
 #include <cassert>
 
 #include "atomic.h"
+#include "notifier.h"
+
+enum class LoadStatus : unsigned int
+{
+	Idle,
+	Loading,
+	Done,
+	Error
+};
 
 //! Engine settings
 struct Settings
 {
+	Atomic<std::string> drumkit_file;
+	Atomic<LoadStatus> drumkit_load_status{LoadStatus::Idle};
+
+	Atomic<std::string> midimap_file;
+	Atomic<LoadStatus> midimap_load_status{LoadStatus::Idle};
+
 	Atomic<bool> enable_velocity_modifier{true};
 	Atomic<float> velocity_modifier_falloff{0.5f};
 	Atomic<float> velocity_modifier_weight{0.25f};
@@ -51,45 +66,15 @@ struct Settings
 	Atomic<std::string> current_file;
 };
 
-//! Getter utility class.
-template <typename T> class SettingRef
+//! Settings getter class.
+struct SettingsGetter
 {
-public:
-	SettingRef(Atomic<T>& value)
-		: value(value)
-	{
-		// string isn't lock free either
-		assert((std::is_same<T, std::string>::value || value.is_lock_free()));
-	}
-
-	bool hasChanged()
-	{
-		T tmp = cache;
-		cache.exchange(value);
-
-		if(firstAccess)
-		{
-			firstAccess = false;
-			return true;
-		}
-
-		return tmp != cache;
-	}
-
-	T getValue() const
-	{
-		return cache;
-	}
+	SettingRef<std::string> drumkit_file;
+	SettingRef<LoadStatus> drumkit_load_status;
 
-private:
-	bool firstAccess{true};
-	Atomic<T>& value;
-	Atomic<T> cache;
-};
+	SettingRef<std::string> midimap_file;
+	SettingRef<LoadStatus> midimap_load_status;
 
-//! Combined getter class.
-struct SettingsGetter
-{
 	SettingRef<bool> enable_velocity_modifier;
 	SettingRef<float> velocity_modifier_falloff;
 	SettingRef<float> velocity_modifier_weight;
@@ -106,7 +91,11 @@ struct SettingsGetter
 	SettingRef<std::string> current_file;
 
 	SettingsGetter(Settings& settings)
-		: enable_velocity_modifier{settings.enable_velocity_modifier}
+		: drumkit_file(settings.drumkit_file)
+		, drumkit_load_status(settings.drumkit_load_status)
+		, midimap_file(settings.midimap_file)
+		, midimap_load_status(settings.midimap_load_status)
+		, enable_velocity_modifier{settings.enable_velocity_modifier}
 		, velocity_modifier_falloff{settings.velocity_modifier_falloff}
 		, velocity_modifier_weight{settings.velocity_modifier_weight}
 		, enable_velocity_randomiser{settings.enable_velocity_randomiser}
@@ -120,6 +109,66 @@ struct SettingsGetter
 	}
 };
 
+//! Settings change notifier class.
+class SettingsNotifier
+{
+public:
+	Notifier<std::string> drumkit_file;
+	Notifier<LoadStatus> drumkit_load_status;
+
+	Notifier<std::string> midimap_file;
+	Notifier<LoadStatus> midimap_load_status;
+
+	Notifier<bool> enable_velocity_modifier;
+	Notifier<float> velocity_modifier_falloff;
+	Notifier<float> velocity_modifier_weight;
+
+	Notifier<bool> enable_velocity_randomiser;
+	Notifier<float> velocity_randomiser_weight;
+
+	Notifier<double> samplerate;
+
+	Notifier<bool> enable_resampling;
+
+	Notifier<int> number_of_files;
+	Notifier<int> number_of_files_loaded;
+	Notifier<std::string> current_file;
+
+	void evaluate()
+	{
+#define EVAL(x) if(settings.x.hasChanged()) { x(settings.x.getValue()); }
+
+		EVAL(drumkit_file);
+		EVAL(drumkit_load_status);
+
+		EVAL(midimap_file);
+		EVAL(midimap_load_status);
+
+		EVAL(enable_velocity_modifier);
+		EVAL(velocity_modifier_falloff);
+		EVAL(velocity_modifier_weight);
+
+		EVAL(enable_velocity_randomiser);
+		EVAL(velocity_randomiser_weight);
+
+		EVAL(samplerate);
+
+		EVAL(enable_resampling);
+
+		EVAL(number_of_files);
+		EVAL(number_of_files_loaded);
+		EVAL(current_file);
+	}
+
+	SettingsNotifier(Settings& settings)
+		: settings(settings)
+	{
+	}
+
+private:
+	SettingsGetter settings;
+};
+
 // lovely reminder: NO, GLOCKE. NOOOO!!
 /*
 enum class IntParams {