Improved performance of ImageData:mapPixel (now up to 2x as fast as in 0.8.0!); love.graphics.newImage, Image:refresh, love.window.setIcon, and ImageRasterizers now prevent other threads from modifying the ImageData used in those functions until they're done accessing it

src/modules/thread/threads.cpp

@@ -42,6 +42,37 @@ Lock::~Lock()
 	mutex->unlock();
 }
 
+EmptyLock::EmptyLock()
+	: mutex(0)
+{
+}
+
+EmptyLock::~EmptyLock()
+{
+	if (mutex)
+		mutex->unlock();
+}
+
+void EmptyLock::setLock(Mutex *m)
+{
+	if (mutex)
+		mutex->unlock();
+
+	mutex = m;
+
+	if (mutex)
+		mutex->lock();
+}
+
+void EmptyLock::setLock(Mutex &m)
+{
+	if (mutex)
+		mutex->unlock();
+
+	mutex = &m;
+	mutex->lock();
+}
+
 Threadable::Threadable()
 {
 	owner = newThread(this);

src/modules/thread/threads.h

@@ -59,6 +59,19 @@ private:
 	Mutex *mutex;
 };
 
+class EmptyLock
+{
+public:
+	EmptyLock();
+	~EmptyLock();
+
+	void setLock(Mutex *m);
+	void setLock(Mutex &m);
+
+private:
+	Mutex *mutex;
+};
+
 class Threadable
 {
 public: