[libcamera-devel] [PATCH 2/5] libcamera: media_device: Add function to get a MediaLink

[Jacopo Mondi]

Add three overloaded functions 'link()' to retrieve a link between two
pads. Each overloaded implementation exposes a different method to
identify the source and sink entities.

Signed-off-by: Jacopo Mondi <jacopo at jmondi.org>
---
 src/libcamera/include/media_device.h |   6 ++
 src/libcamera/media_device.cpp       | 119 +++++++++++++++++++++++++++
 2 files changed, 125 insertions(+)

diff --git a/src/libcamera/include/media_device.h b/src/libcamera/include/media_device.h
index 9f45fc7..3228ad5 100644
--- a/src/libcamera/include/media_device.h
+++ b/src/libcamera/include/media_device.h
@@ -40,6 +40,12 @@ public:
 	const std::vector<MediaEntity *> &entities() const { return entities_; }
 	MediaEntity *getEntityByName(const std::string &name) const;
 
+	MediaLink *link(const std::string sourceName, unsigned int sourceIdx,
+			const std::string sinkName, unsigned int sinkIdx) const;
+	MediaLink *link(const MediaEntity *source, unsigned int sourceIdx,
+			const MediaEntity *sink, unsigned int sinkIdx) const;
+	MediaLink *link(const MediaPad *source, const MediaPad *sink) const;
+
 private:
 	std::string driver_;
 	std::string devnode_;
diff --git a/src/libcamera/media_device.cpp b/src/libcamera/media_device.cpp
index 2f9490c..6892300 100644
--- a/src/libcamera/media_device.cpp
+++ b/src/libcamera/media_device.cpp
@@ -306,6 +306,125 @@ MediaEntity *MediaDevice::getEntityByName(const std::string &name) const
 	return nullptr;
 }
 
+/**
+ * \brief Return the MediaLink that connects two entities identified by name
+ * \param sourceName The source entity name
+ * \param sourceIdx The index of the source pad
+ * \param sinkName The sink entity name
+ * \param sinkIdx The index of the sink pad
+ *
+ * Find link that connects the pads at index \a sourceIdx of the source
+ * entity with name \a sourceName, to the pad at index \a sinkIdx of the
+ * sink entity with name \a sinkName, if any.
+ *
+ * \sa MediaDevice::link(const MediaEntity *source, unsigned int sourceIdx, const MediaEntity *sink, unsigned int sinkIdx) const
+ * \sa MediaDevice::link(const MediaPad *source, const MediaPad *sink) const
+ *
+ * \return The link that connects the two entities, nullptr otherwise
+ */
+MediaLink *MediaDevice::link(const std::string sourceName, unsigned int sourceIdx,
+			     const std::string sinkName, unsigned int sinkIdx) const
+{
+	const MediaEntity *source = getEntityByName(sourceName);
+	if (!source) {
+		LOG(Error) << "Failed to find entity with name: "
+			   << sourceName << "\n";
+		return nullptr;
+	}
+
+	const MediaPad *sourcePad = source->getPadByIndex(sourceIdx);
+	if (!sourcePad) {
+		LOG(Error) << "Entity \"" << sourceName << "\" "
+			   << "has no pad at index " << sourceIdx << "\n";
+		return nullptr;
+	}
+
+	const MediaEntity *sink = getEntityByName(sinkName);
+	if (!sink) {
+		LOG(Error) << "Failed to find entity with name: "
+			   << sinkName << "\n";
+		return nullptr;
+	}
+
+	const MediaPad *sinkPad = sink->getPadByIndex(sinkIdx);
+	if (!sinkPad) {
+		LOG(Error) << "Entity \"" << sinkName << "\" "
+			   << "has no pad at index " << sinkIdx << "\n";
+		return nullptr;
+	}
+
+	return link(sourcePad, sinkPad);
+}
+
+/**
+ * \brief Return the MediaLink that connects two entities
+ * \param source The source entity
+ * \param sourceIdx The index of the source pad
+ * \param sink The sink entity
+ * \param sinkIdx The index of the sink pad
+ *
+ * Find link that connects the pads at index \a sourceIdx of the source
+ * entity \a source, to the pad at index \a sinkIdx of the sink entity \a
+ * sink, if any.
+ *
+ * \sa MediaDevice::link(const std::string sourceName, unsigned int sourceIdx, const std::string sinkName, unsigned int sinkIdx) const
+ * \sa MediaDevice::link(const MediaPad *source, const MediaPad *sink) const
+ *
+ * \return The link that connects the two entities, nullptr otherwise
+ */
+MediaLink *MediaDevice::link(const MediaEntity *source, unsigned int sourceIdx,
+			     const MediaEntity *sink, unsigned int sinkIdx) const
+{
+
+	const MediaPad *sourcePad = source->getPadByIndex(sourceIdx);
+	if (!sourcePad) {
+		LOG(Error) << "Entity \"" << source->name() << "\" "
+			   << "has no pad at index " << sourceIdx << "\n";
+		return nullptr;
+	}
+
+	const MediaPad *sinkPad = sink->getPadByIndex(sinkIdx);
+	if (!sinkPad) {
+		LOG(Error) << "Entity \"" << sink->name() << "\" "
+			   << "has no pad at index " << sinkIdx << "\n";
+		return nullptr;
+	}
+
+	return link(sourcePad, sinkPad);
+}
+
+/**
+ * \brief Return the MediaLink that connects two pads
+ * \param source The source pad
+ * \param sink The sink pad
+ *
+ * \sa MediaDevice::link(const std::string sourceName, unsigned int sourceIdx, const std::string sinkName, unsigned int sinkIdx) const
+ * \sa MediaDevice::link(const MediaEntity *source, unsigned int sourceIdx, const MediaEntity *sink, unsigned int sinkIdx) const
+ *
+ * \return The link that connects the two pads, nullptr otherwise
+ */
+MediaLink *MediaDevice::link(const MediaPad *source, const MediaPad *sink) const
+{
+	if (!source || !sink)
+		return nullptr;
+
+	/*
+	 * Now that we have made sure all instances are valid, compare
+	 * their ids to find a matching link.
+	 */
+	for (MediaLink *link : source->links()) {
+		if (link->sink()->id() != sink->id())
+			continue;
+
+		if (link->sink()->entity()->id() != sink->entity()->id())
+			continue;
+
+		return link;
+	}
+
+	return nullptr;
+}
+
 /**
  * \var MediaDevice::objects_
  * \brief Global map of media objects (entities, pads, links) keyed by their
-- 
2.20.1