Add love.audiodisconnected callback.

The callback is fired when the audio has been disconnected.

src/modules/audio/openal/Pool.cpp

@@ -20,6 +20,7 @@
 
 #include "Pool.h"
 
+#include "event/Event.h"
 #include "Source.h"
 
 namespace love
@@ -29,8 +30,10 @@ namespace audio
 namespace openal
 {
 
-Pool::Pool()
-	: sources()
+Pool::Pool(ALCdevice *device)
+	: device(device)
+	, sources()
+	, disconnectNotified(false)
 	, totalSources(0)
 {
 	// Clear errors.
@@ -101,8 +104,34 @@ bool Pool::isPlaying(Source *s)
 
 void Pool::update()
 {
+#ifndef ALC_CONNECTED
+	constexpr ALCenum ALC_CONNECTED = 0x313;
+#endif
+
 	thread::Lock lock(mutex);
 
+	static bool disconnectExtSupported = alcIsExtensionPresent(device, "ALC_EXT_Disconnect") == ALC_TRUE;
+
+	// Device disconnection event
+	if (disconnectExtSupported)
+	{
+		auto eventModule = Module::getInstance<event::Event>(Module::M_EVENT);
+		if (eventModule)
+		{
+			ALCint connected;
+			alcGetIntegerv(device, ALC_CONNECTED, 1, &connected);
+
+			if (connected)
+				disconnectNotified = false;
+			else if (!disconnectNotified)
+			{
+				StrongRef<event::Message> msg(new event::Message("audiodisconnected"), Acquire::NORETAIN);
+				eventModule->push(msg);
+				disconnectNotified = true;
+			}
+		}
+	}
+
 	std::vector<Source *> torelease;
 
 	for (const auto &i : playing)