[libcamera-devel] [PATCH v2 8/8] cam: Add support for viewfinder through DRM/KMS

[paul.elder at ideasonboard.com]

Hi Laurent,

On Fri, Jul 30, 2021 at 04:03:06AM +0300, Laurent Pinchart wrote:
> Use the KMSSink class to display the viewfinder stream, if any, through
> DRM/KMS. The output connector is selected through the new -D/--display
> argument.
> 
> Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> ---
> Changes since v1:
> 
> - Validate display option in CamApp::init()
> ---
>  src/cam/camera_session.cpp | 28 ++++++++++++++++++++++++++++
>  src/cam/main.cpp           |  6 ++++++
>  src/cam/main.h             |  1 +
>  3 files changed, 35 insertions(+)
> 
> diff --git a/src/cam/camera_session.cpp b/src/cam/camera_session.cpp
> index 4f1f9ec8eb10..8d8c1b8ba469 100644
> --- a/src/cam/camera_session.cpp
> +++ b/src/cam/camera_session.cpp
> @@ -16,6 +16,9 @@
>  #include "camera_session.h"
>  #include "event_loop.h"
>  #include "file_sink.h"
> +#ifdef HAVE_KMS
> +#include "kms_sink.h"
> +#endif
>  #include "main.h"
>  #include "stream_options.h"
>  
> @@ -66,6 +69,26 @@ CameraSession::CameraSession(CameraManager *cm,
>  
>  	bool strictFormats = options_.isSet(OptStrictFormats);
>  
> +	if (options_.isSet(OptDisplay)) {

I was wondering if this needs a guard too, but I guess this will just
never be satisfied, so maybe this is cleaner.

Reviewed-by: Paul Elder <paul.elder at ideasonboard.com>

> +		if (options_.isSet(OptFile)) {
> +			std::cerr << "--display and --file options are mutually exclusive"
> +				  << std::endl;
> +			return;
> +		}
> +
> +		if (roles.size() != 1) {
> +			std::cerr << "Display doesn't support multiple streams"
> +				  << std::endl;
> +			return;
> +		}
> +
> +		if (roles[0] != StreamRole::Viewfinder) {
> +			std::cerr << "Display requires a viewfinder stream"
> +				  << std::endl;
> +			return;
> +		}
> +	}
> +
>  	switch (config->validate()) {
>  	case CameraConfiguration::Valid:
>  		break;
> @@ -161,6 +184,11 @@ int CameraSession::start()
>  
>  	camera_->requestCompleted.connect(this, &CameraSession::requestComplete);
>  
> +#ifdef HAVE_KMS
> +	if (options_.isSet(OptDisplay))
> +		sink_ = std::make_unique<KMSSink>(options_[OptDisplay].toString());
> +#endif
> +
>  	if (options_.isSet(OptFile)) {
>  		if (!options_[OptFile].toString().empty())
>  			sink_ = std::make_unique<FileSink>(options_[OptFile]);
> diff --git a/src/cam/main.cpp b/src/cam/main.cpp
> index 34cbc3229563..c7f664b903e0 100644
> --- a/src/cam/main.cpp
> +++ b/src/cam/main.cpp
> @@ -132,6 +132,12 @@ int CamApp::parseOptions(int argc, char *argv[])
>  			 "Capture until interrupted by user or until <count> frames captured",
>  			 "capture", ArgumentOptional, "count", false,
>  			 OptCamera);
> +#ifdef HAVE_KMS
> +	parser.addOption(OptDisplay, OptionString,
> +			 "Display viewfinder through DRM/KMS on specified connector",
> +			 "display", ArgumentOptional, "connector", false,
> +			 OptCamera);
> +#endif
>  	parser.addOption(OptFile, OptionString,
>  			 "Write captured frames to disk\n"
>  			 "If the file name ends with a '/', it sets the directory in which\n"
> diff --git a/src/cam/main.h b/src/cam/main.h
> index d22451f59817..1c2fab763698 100644
> --- a/src/cam/main.h
> +++ b/src/cam/main.h
> @@ -10,6 +10,7 @@
>  enum {
>  	OptCamera = 'c',
>  	OptCapture = 'C',
> +	OptDisplay = 'D',
>  	OptFile = 'F',
>  	OptHelp = 'h',
>  	OptInfo = 'I',
> -- 
> Regards,
> 
> Laurent Pinchart
>