libcamera: camera: Handle camera objects through shared pointers

The Camera class is explicitly reference-counted to manage the lifetime
of camera objects. Replace this open-coded implementation with usage of
the std::shared_ptr<> class.

This API change prevents pipeline handlers from subclassing the Camera
class. This isn't deemed to be an issue. Mark the class final to make
this explicit.

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/camera.h

@@ -7,22 +7,25 @@
 #ifndef __LIBCAMERA_CAMERA_H__
 #define __LIBCAMERA_CAMERA_H__
 
+#include <memory>
 #include <string>
 
 namespace libcamera {
 
-class Camera
+class Camera final
 {
 public:
-	Camera(const std::string &name);
+	static std::shared_ptr<Camera> create(const std::string &name);
+
+	Camera(const Camera &) = delete;
+	void operator=(const Camera &) = delete;
 
 	const std::string &name() const;
-	void get();
-	void put();
 
 private:
-	virtual ~Camera() { };
-	int ref_;
+	explicit Camera(const std::string &name);
+	~Camera();
+
 	std::string name_;
 };