Use a mutex when painting or changing gfx surface.

libgag/include/EventListener.h

@@ -40,6 +40,7 @@ class EventListener {
 	static std::condition_variable startedCond;
 	static std::mutex doneMutex;
 	static std::condition_variable doneCond;
+	static std::mutex renderMutex;
 	void setPainter(std::function<void()> f);
 	void paint();
 private:

libgag/src/EventListener.cpp

@@ -25,6 +25,7 @@ std::mutex EventListener::startMutex;
 std::condition_variable EventListener::startedCond;
 std::mutex EventListener::doneMutex;
 std::condition_variable EventListener::doneCond;
+std::mutex EventListener::renderMutex;
 
 #define SIZE_MOVE_TIMER_ID 1
 #if defined(_WIN32) || defined(__MINGW32__) || defined(__MINGW64__)
@@ -52,12 +53,15 @@ EventListener::~EventListener()
 }
 void EventListener::setPainter(std::function<void()> f)
 {
+	std::unique_lock<std::mutex> lock(renderMutex);
 	painter = f;
 }
 void EventListener::paint()
 {
 	if (painter)
 	{
+		std::unique_lock<std::mutex> lock(renderMutex);
+		gfx->createGLContext();
 		painter();
 		gfx->nextFrame();
 	}

libgag/src/GraphicContext.cpp

@@ -21,6 +21,7 @@
 #include <Toolkit.h>
 #include <FileManager.h>
 #include <SupportFunctions.h>
+#include "EventListener.h"
 #include <assert.h>
 #include <string>
 #include <sstream>
@@ -2060,6 +2061,7 @@ namespace GAGCore
 	}
 
 	SDL_Surface* GraphicContext::getOrCreateSurface(int w, int h, Uint32 flags) {
+		std::unique_lock<std::mutex> lock(EventListener::instance()->renderMutex);
 		if (flags & USEGPU)
 		{
 			if (sdlsurface)

src/Engine.cpp

@@ -508,6 +508,14 @@ int Engine::run(void)
 				if (nextGuiStep == 0)
 				{
 					// we draw
+					static bool isPainterSet = false;
+					if (!isPainterSet)
+					{
+						EventListener::instance()->setPainter(std::bind(GameGUI::drawAll, &gui, gui.localTeamNo));
+						isPainterSet = true;
+					}
+					std::unique_lock<std::mutex> lock(EventListener::instance()->renderMutex);
+					globalContainer->gfx->createGLContext();
 					gui.drawAll(gui.localTeamNo);
 					globalContainer->gfx->nextFrame();
 				}

src/GameGUI.cpp

@@ -4380,7 +4380,6 @@ void GameGUI::drawInGameScrollableText(void)
 
 void GameGUI::drawAll(int team)
 {
-	EventListener::instance()->setPainter(std::bind(&GameGUI::drawAll, this, team));
 	// draw the map
 	Uint32 drawOptions =	(drawHealthFoodBar ? Game::DRAW_HEALTH_FOOD_BAR : 0) |
 								(drawPathLines ?  Game::DRAW_PATH_LINE : 0) |