[libcamera-devel] [PATCH] cam: Add --monitor option

[Kieran Bingham]

Hi Umang,

On 13/07/2020 13:11, Umang Jain wrote:
> Add --monitor to monitor new hotplug and unplug camera events from
> the CameraManager.
> 
> Signed-off-by: Umang Jain <email at uajain.com>
> ---
>  src/cam/main.cpp | 24 ++++++++++++++++++++++++
>  src/cam/main.h   |  1 +
>  2 files changed, 25 insertions(+)
> 
> diff --git a/src/cam/main.cpp b/src/cam/main.cpp
> index 2512fe9..3488315 100644
> --- a/src/cam/main.cpp
> +++ b/src/cam/main.cpp
> @@ -36,6 +36,8 @@ public:
>  	void quit();
>  
>  private:
> +	void cameraAdded(std::shared_ptr<Camera> cam);
> +	void cameraRemoved(std::shared_ptr<Camera> cam);
>  	int parseOptions(int argc, char *argv[]);
>  	int prepareConfig();
>  	int listControls();
> @@ -115,6 +117,10 @@ int CamApp::init(int argc, char **argv)
>  		ret = prepareConfig();
>  		if (ret)
>  			return ret;
> +	} else if (options_.isSet(OptMonitor)) {
> +		cm_->cameraAdded.connect(this, &CamApp::cameraAdded);
> +		cm_->cameraRemoved.connect(this, &CamApp::cameraRemoved);

Should we add these event notifiers unconditionally?

I think if we are running any kind of event loop, or capture - if
something gets unplugged it would be nice to know about it.

What happens if we pull out a UVC camera while streaming with cam?

Still, I think any graceful handling of hotplug in cam is separate to
adding a monitor, which is useful on it's own, so:

Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>


> +		std::cout << "Monitoring new hotplug and unplug events..." << std::endl;
>  	}
>  
>  	loop_ = new EventLoop(cm_->eventDispatcher());
> @@ -179,6 +185,8 @@ int CamApp::parseOptions(int argc, char *argv[])
>  			 "list-controls");
>  	parser.addOption(OptListProperties, OptionNone, "List cameras properties",
>  			 "list-properties");
> +	parser.addOption(OptMonitor, OptionNone, "Monitor for hotplug and unplug camera events",
> +			 "monitor");
>  
>  	options_ = parser.parse(argc, argv);
>  	if (!options_.valid())
> @@ -293,6 +301,16 @@ int CamApp::infoConfiguration()
>  	return 0;
>  }
>  
> +void CamApp::cameraAdded(std::shared_ptr<Camera> cam)
> +{
> +	std::cout << "Camera Added: " << cam->name() << std::endl;
> +}
> +
> +void CamApp::cameraRemoved(std::shared_ptr<Camera> cam)
> +{
> +	std::cout << "Camera Removed: " << cam->name() << std::endl;
> +}
> +
>  int CamApp::run()
>  {
>  	int ret;
> @@ -330,6 +348,12 @@ int CamApp::run()
>  		return capture.run(loop_, options_);
>  	}
>  
> +	if (options_.isSet(OptMonitor)) {
> +		ret = loop_->exec();
> +		if (ret)
> +			std::cout << "Failed to run monitor loop" << std::endl;
> +	}
> +
>  	return 0;
>  }
>  
> diff --git a/src/cam/main.h b/src/cam/main.h
> index 4a130d8..f61d288 100644
> --- a/src/cam/main.h
> +++ b/src/cam/main.h
> @@ -15,6 +15,7 @@ enum {
>  	OptInfo = 'I',
>  	OptList = 'l',
>  	OptListProperties = 'p',
> +	OptMonitor = 'm',
>  	OptStream = 's',
>  	OptListControls = 256,
>  };
> 

-- 
Regards
--
Kieran