libcamera: media_object: Add MediaPad string representations

Facilitate easy representations of a MediaPad object by preparing
it as a string and supporting output streams.

A MediaPad will be report in the following style:

  'imx283 1-001a'[0]

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Stefan Klug <stefan.klug@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

include/libcamera/internal/media_object.h

@@ -71,6 +71,8 @@ public:
 
 	void addLink(MediaLink *link);
 
+	std::string toString() const;
+
 private:
 	LIBCAMERA_DISABLE_COPY_AND_MOVE(MediaPad)
 
@@ -85,6 +87,8 @@ private:
 	std::vector<MediaLink *> links_;
 };
 
+std::ostream &operator<<(std::ostream &out, const MediaPad &pad);
+
 class MediaEntity : public MediaObject
 {
 public:

src/libcamera/media_object.cpp

@@ -235,6 +235,31 @@ void MediaPad::addLink(MediaLink *link)
 	links_.push_back(link);
 }
 
+/**
+ * \brief Generate a string representation of the MediaPad
+ * \return A string representing the MediaPad
+ */
+std::string MediaPad::toString() const
+{
+	std::stringstream ss;
+	ss << *this;
+
+	return ss.str();
+}
+
+/**
+ * \brief Insert a text representation of a MediaPad into an output stream
+ * \param[in] out The output stream
+ * \param[in] pad The MediaPad
+ * \return The output stream \a out
+ */
+std::ostream &operator<<(std::ostream &out, const MediaPad &pad)
+{
+	out << "'" << pad.entity()->name() << "'[" << pad.index() << "]";
+
+	return out;
+}
+
 /**
  * \class MediaEntity
  * \brief The MediaEntity represents an entity in the media graph