[libcamera-devel] [PATCH 2/4] libcamera: camera_manager: Introduce signals when a camera is added/removed

[Umang Jain]

Emit 'cameraAdded' and 'cameraRemoved' from CameraManager to enable
hotplug and hot-unplug support in appplications like QCam.

Signed-off-by: Umang Jain <email at uajain.com>
---
 include/libcamera/camera_manager.h |  4 ++++
 src/libcamera/camera_manager.cpp   | 20 ++++++++++++++++++++
 2 files changed, 24 insertions(+)

diff --git a/include/libcamera/camera_manager.h b/include/libcamera/camera_manager.h
index 079f848..558bb96 100644
--- a/include/libcamera/camera_manager.h
+++ b/include/libcamera/camera_manager.h
@@ -13,6 +13,7 @@
 #include <vector>
 
 #include <libcamera/object.h>
+#include <libcamera/signal.h>
 
 namespace libcamera {
 
@@ -42,6 +43,9 @@ public:
 	void setEventDispatcher(std::unique_ptr<EventDispatcher> dispatcher);
 	EventDispatcher *eventDispatcher();
 
+	Signal<Camera *> cameraAdded;
+	Signal<Camera *> cameraRemoved;
+
 private:
 	static const std::string version_;
 	static CameraManager *self_;
diff --git a/src/libcamera/camera_manager.cpp b/src/libcamera/camera_manager.cpp
index c75979a..6438f87 100644
--- a/src/libcamera/camera_manager.cpp
+++ b/src/libcamera/camera_manager.cpp
@@ -391,6 +391,23 @@ std::shared_ptr<Camera> CameraManager::get(dev_t devnum)
 	return iter->second.lock();
 }
 
+/**
+ * \var CameraManager::cameraAdded
+ * \brief Signal emitted when a new camera is added in CameraManager
+ *
+ * This signal is emitted when a new camera is added by the CameraManager
+ * in the list of cameras it manages. A pointer to the newly-added camera
+ * is passed as a parameter.
+ */
+
+/**
+ * \var CameraManager::cameraRemoved
+ * \brief Signal emitted when a camera is removed in CameraManager
+ *
+ * This signal is emitted when a camera is removed from the CameraManager.
+ * A pointer to the removed camera is passed as a parameter.
+ */
+
 /**
  * \brief Add a camera to the camera manager
  * \param[in] camera The camera to be added
@@ -409,7 +426,9 @@ void CameraManager::addCamera(std::shared_ptr<Camera> camera, dev_t devnum)
 {
 	ASSERT(Thread::current() == p_.get());
 
+	Camera *cam = camera.get();
 	p_->addCamera(camera, devnum);
+	cameraAdded.emit(cam);
 }
 
 /**
@@ -427,6 +446,7 @@ void CameraManager::removeCamera(Camera *camera)
 	ASSERT(Thread::current() == p_.get());
 
 	p_->removeCamera(camera);
+	cameraRemoved.emit(camera);
 }
 
 /**
-- 
2.26.2