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

[Laurent Pinchart]

Hi Paul,

On Wed, Aug 04, 2021 at 04:10:57PM +0900, paul.elder at ideasonboard.com wrote:
> 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.

Good point. A guard would avoid dead code, so I think that's valuable.
I'll add one.

> 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