libcamera: signal: Split Slot implementation to reusable classes

Move the Slot* classes to bound_method.{h,cpp} and rename them to
Bound*Method*. They will be reused to implement asynchronous method
invocation similar to cross-thread signal delivery.

This is only a move and rename, no functional changes are included.

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

src/libcamera/signal.cpp

@@ -7,10 +7,6 @@
 
 #include <libcamera/signal.h>
 
-#include "message.h"
-#include "thread.h"
-#include "utils.h"
-
 /**
  * \file signal.h
  * \brief Signal & slot implementation
@@ -57,25 +53,6 @@ namespace libcamera {
  * passed through the signal will remain valid after the signal is emitted.
  */
 
-void SlotBase::disconnect(SignalBase *signal)
-{
-	if (object_)
-		object_->disconnect(signal);
-}
-
-void SlotBase::activatePack(void *pack)
-{
-	Object *obj = static_cast<Object *>(object_);
-
-	if (Thread::current() == obj->thread()) {
-		invokePack(pack);
-	} else {
-		std::unique_ptr<Message> msg =
-			utils::make_unique<SignalMessage>(this, pack);
-		obj->postMessage(std::move(msg));
-	}
-}
-
 /**
  * \fn Signal::connect(T *object, void(T::*func)(Args...))
  * \brief Connect the signal to a member function slot