libcamera: pipeline_handler: Optimise factory implementation

The REGISTER_PIPELINE_HANDLER() macro defines and instantiates a
subclass of the PipelineHandlerFactory class that specialises the
virtual create() method. Now that create() does more than just creating
an instance, boilerplate code gets duplicated between different
factories.

Factor out the instance creation code to a new virtual createInstance()
method, and turn create() into a non-virtual method of the base class
that can then be defined in the .cpp file.

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

src/libcamera/include/pipeline_handler.h

@@ -107,17 +107,16 @@ public:
 	PipelineHandlerFactory(const char *name);
 	virtual ~PipelineHandlerFactory() { };
 
-	virtual std::shared_ptr<PipelineHandler> create(CameraManager *manager) = 0;
+	std::shared_ptr<PipelineHandler> create(CameraManager *manager);
 
 	const std::string &name() const { return name_; }
 
 	static void registerType(PipelineHandlerFactory *factory);
 	static std::vector<PipelineHandlerFactory *> &factories();
 
-protected:
-	void setInfo(PipelineHandler *handler, const char *name);
-
 private:
+	virtual PipelineHandler *createInstance(CameraManager *manager) = 0;
+
 	std::string name_;
 };
 
@@ -126,12 +125,11 @@ class handler##Factory final : public PipelineHandlerFactory		\
 {									\
 public:									\
 	handler##Factory() : PipelineHandlerFactory(#handler) {}	\
-	std::shared_ptr<PipelineHandler> create(CameraManager *manager)	\
+									\
+private:								\
+	PipelineHandler *createInstance(CameraManager *manager)		\
 	{								\
-		std::shared_ptr<handler> h =				\
-			std::make_shared<handler>(manager);		\
-		setInfo(h.get(), #handler);				\
-		return h;						\
+		return new handler(manager);				\
 	}								\
 };									\
 static handler##Factory global_##handler##Factory;

src/libcamera/pipeline_handler.cpp

@@ -539,17 +539,18 @@ PipelineHandlerFactory::PipelineHandlerFactory(const char *name)
 }
 
 /**
- * \fn PipelineHandlerFactory::create()
  * \brief Create an instance of the PipelineHandler corresponding to the factory
  * \param[in] manager The camera manager
  *
- * This virtual function is implemented by the REGISTER_PIPELINE_HANDLER()
- * macro. It creates a pipeline handler instance associated with the camera
- * \a manager.
- *
- * \return a pointer to a newly constructed instance of the PipelineHandler
- * subclass corresponding to the factory
+ * \return A shared pointer to a new instance of the PipelineHandler subclass
+ * corresponding to the factory
  */
+std::shared_ptr<PipelineHandler> PipelineHandlerFactory::create(CameraManager *manager)
+{
+	PipelineHandler *handler = createInstance(manager);
+	handler->name_ = name_.c_str();
+	return std::shared_ptr<PipelineHandler>(handler);
+}
 
 /**
  * \fn PipelineHandlerFactory::name()
@@ -589,15 +590,17 @@ std::vector<PipelineHandlerFactory *> &PipelineHandlerFactory::factories()
 }
 
 /**
- * \brief Set the information of a given pipeline handler
- * \param[in] handler The handler whose info is to be set
- * \param[in] name The name of the pipeline handler
+ * \fn PipelineHandlerFactory::createInstance()
+ * \brief Create an instance of the PipelineHandler corresponding to the factory
+ * \param[in] manager The camera manager
+ *
+ * This virtual function is implemented by the REGISTER_PIPELINE_HANDLER()
+ * macro. It creates a pipeline handler instance associated with the camera
+ * \a manager.
+ *
+ * \return a pointer to a newly constructed instance of the PipelineHandler
+ * subclass corresponding to the factory
  */
-void PipelineHandlerFactory::setInfo(PipelineHandler *handler,
-				     const char *name)
-{
-	handler->name_ = name;
-}
 
 /**
  * \def REGISTER_PIPELINE_HANDLER