Deactivate the CameraServer by default.

Add `monitoring_feeds` property to `CameraServer`.
This saves resources for games that don't use a physical camera.

modules/camera/camera_linux.cpp

@@ -162,11 +162,25 @@ bool CameraLinux::_can_query_format(int p_file_descriptor, int p_type) {
 	return ioctl(p_file_descriptor, VIDIOC_G_FMT, &format) != -1;
 }
 
-CameraLinux::CameraLinux() {
-	camera_thread.start(CameraLinux::camera_thread_func, this);
+inline void CameraLinux::set_monitoring_feeds(bool p_monitoring_feeds) {
+	if (p_monitoring_feeds == monitoring_feeds) {
+		return;
+	}
+
+	CameraServer::set_monitoring_feeds(p_monitoring_feeds);
+	if (p_monitoring_feeds) {
+		camera_thread.start(CameraLinux::camera_thread_func, this);
+	} else {
+		exit_flag.set();
+		if (camera_thread.is_started()) {
+			camera_thread.wait_to_finish();
+		}
+	}
 }
 
 CameraLinux::~CameraLinux() {
 	exit_flag.set();
-	camera_thread.wait_to_finish();
+	if (camera_thread.is_started()) {
+		camera_thread.wait_to_finish();
+	}
 }

modules/camera/camera_linux.h

@@ -52,6 +52,8 @@ private:
 	bool _can_query_format(int p_file_descriptor, int p_type);
 
 public:
-	CameraLinux();
+	CameraLinux() = default;
 	~CameraLinux();
+
+	void set_monitoring_feeds(bool p_monitoring_feeds) override;
 };

modules/camera/camera_macos.h

@@ -37,7 +37,8 @@
 
 class CameraMacOS : public CameraServer {
 public:
-	CameraMacOS();
+	CameraMacOS() = default;
 
 	void update_feeds();
+	void set_monitoring_feeds(bool p_monitoring_feeds) override;
 };

modules/camera/camera_macos.mm

@@ -359,10 +359,20 @@ void CameraMacOS::update_feeds() {
 	};
 }
 
-CameraMacOS::CameraMacOS() {
-	// Find available cameras we have at this time
-	update_feeds();
+void CameraMacOS::set_monitoring_feeds(bool p_monitoring_feeds) {
+	if (p_monitoring_feeds == monitoring_feeds) {
+		return;
+	}
 
-	// should only have one of these....
-	device_notifications = [[MyDeviceNotifications alloc] initForServer:this];
+	CameraServer::set_monitoring_feeds(p_monitoring_feeds);
+	if (p_monitoring_feeds) {
+		// Find available cameras we have at this time.
+		update_feeds();
+
+		// Get notified on feed changes.
+		device_notifications = [[MyDeviceNotifications alloc] initForServer:this];
+	} else {
+		// Stop monitoring feed changes.
+		device_notifications = nil;
+	}
 }