libcamera: framebuffer: Enable attaching additional data to FrameBuffer

We cannot have a subclass of FrameBuffer because it is marked as final.
This adds a FrameBuffer constructor with FrameBuffer::Private. So we
can attach some additional resources with FrameBuffer through a
customized FrameBuffer::Private class.

Signed-off-by: Hirokazu Honda <hiroh@chromium.org>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>

include/libcamera/framebuffer.h

@@ -57,6 +57,8 @@ public:
 	};
 
 	FrameBuffer(const std::vector<Plane> &planes, unsigned int cookie = 0);
+	FrameBuffer(std::unique_ptr<Private> d,
+		    const std::vector<Plane> &planes, unsigned int cookie = 0);
 
 	const std::vector<Plane> &planes() const { return planes_; }
 	Request *request() const;

include/libcamera/internal/framebuffer.h

@@ -19,6 +19,7 @@ class FrameBuffer::Private : public Extensible::Private
 
 public:
 	Private();
+	virtual ~Private();
 
 	void setRequest(Request *request) { request_ = request; }
 	bool isContiguous() const { return isContiguous_; }

src/libcamera/framebuffer.cpp

@@ -119,6 +119,13 @@ FrameBuffer::Private::Private()
 {
 }
 
+/**
+ * \brief FrameBuffer::Private destructor
+ */
+FrameBuffer::Private::~Private()
+{
+}
+
 /**
  * \fn FrameBuffer::Private::setRequest()
  * \brief Set the request this buffer belongs to
@@ -237,8 +244,21 @@ ino_t fileDescriptorInode(const SharedFD &fd)
  * \param[in] cookie Cookie
  */
 FrameBuffer::FrameBuffer(const std::vector<Plane> &planes, unsigned int cookie)
-	: Extensible(std::make_unique<Private>()), planes_(planes),
+	: FrameBuffer(std::make_unique<Private>(), planes, cookie)
-	  cookie_(cookie)
+{
+}
+
+/**
+ * \brief Construct a FrameBuffer with an extensible private class and an array
+ * of planes
+ * \param[in] d The extensible private class
+ * \param[in] planes The frame memory planes
+ * \param[in] cookie Cookie
+ */
+FrameBuffer::FrameBuffer(std::unique_ptr<Private> d,
+			 const std::vector<Plane> &planes,
+			 unsigned int cookie)
+	: Extensible(std::move(d)), planes_(planes), cookie_(cookie)
 {
 	metadata_.planes_.resize(planes_.size());