libcamera: timer: Bind timers to threads

The Timer instances are registered with the event dispatcher instance of
the CameraManager. This makes it impossible to use timers in other
threads.

Fix this by inheriting from Object, which allows binding instances to a
thread, and register them with the event dispatcher for the thread they
are bound to.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>

include/libcamera/timer.h

@@ -9,11 +9,14 @@
 
 #include <cstdint>
 
+#include <libcamera/object.h>
 #include <libcamera/signal.h>
 
 namespace libcamera {
 
-class Timer
+class Message;
+
+class Timer : public Object
 {
 public:
 	Timer();
@@ -28,7 +31,13 @@ public:
 
 	Signal<Timer *> timeout;
 
+protected:
+	void message(Message *msg) override;
+
 private:
+	void registerTimer();
+	void unregisterTimer();
+
 	unsigned int interval_;
 	uint64_t deadline_;
 };