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/bound_method.cpp

@@ -0,0 +1,33 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2019, Google Inc.
+ *
+ * bound_method.cpp - Method bind and invocation
+ */
+
+#include <libcamera/bound_method.h>
+
+#include "message.h"
+#include "thread.h"
+#include "utils.h"
+
+namespace libcamera {
+
+void BoundMethodBase::disconnect(SignalBase *signal)
+{
+	if (object_)
+		object_->disconnect(signal);
+}
+
+void BoundMethodBase::activatePack(void *pack)
+{
+	if (Thread::current() == object_->thread()) {
+		invokePack(pack);
+	} else {
+		std::unique_ptr<Message> msg =
+			utils::make_unique<SignalMessage>(this, pack);
+		object_->postMessage(std::move(msg));
+	}
+}
+
+} /* namespace libcamera */

src/libcamera/include/message.h

@@ -11,8 +11,8 @@
 
 namespace libcamera {
 
+class BoundMethodBase;
 class Object;
-class SlotBase;
 class Thread;
 
 class Message
@@ -44,12 +44,12 @@ private:
 class SignalMessage : public Message
 {
 public:
-	SignalMessage(SlotBase *slot, void *pack)
-		: Message(Message::SignalMessage), slot_(slot), pack_(pack)
+	SignalMessage(BoundMethodBase *method, void *pack)
+		: Message(Message::SignalMessage), method_(method), pack_(pack)
 	{
 	}
 
-	SlotBase *slot_;
+	BoundMethodBase *method_;
 	void *pack_;
 };
 

src/libcamera/meson.build

@@ -1,4 +1,5 @@
 libcamera_sources = files([
+    'bound_method.cpp',
     'buffer.cpp',
     'camera.cpp',
     'camera_manager.cpp',

src/libcamera/message.cpp

@@ -114,12 +114,12 @@ Message::Type Message::registerMessageType()
 /**
  * \fn SignalMessage::SignalMessage()
  * \brief Construct a SignalMessage
- * \param[in] slot The slot that the signal targets
+ * \param[in] method The slot that the signal targets
  * \param[in] pack The signal arguments
  */
 
 /**
- * \var SignalMessage::slot_
+ * \var SignalMessage::method_
  * \brief The slot that the signal targets
  */
 

src/libcamera/object.cpp

@@ -90,7 +90,7 @@ void Object::message(Message *msg)
 	switch (msg->type()) {
 	case Message::SignalMessage: {
 		SignalMessage *smsg = static_cast<SignalMessage *>(msg);
-		smsg->slot_->invokePack(smsg->pack_);
+		smsg->method_->invokePack(smsg->pack_);
 		break;
 	}
 

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