[libcamera-devel] [PATCH v3 6/6] libcamera: camera: extend camera object to support configuration of streams

[Laurent Pinchart]

Hi Niklas,

Thank you for the patch.

On Sun, Jan 27, 2019 at 01:22:08AM +0100, Niklas Söderlund wrote:
> Extend the camera to support reading and configuring of formats for

s/of formats/formats/

> groups of streams. The implementation in the Camera are minimalistic as
> the heavy lifting are done by the pipeline handler implementations.
> 
> The most important functionality the camera provides in this context is
> validation of data structures passed to it from the application and
> access control to the pipeline handler.
> 
> Signed-off-by: Niklas Söderlund <niklas.soderlund at ragnatech.se>
> ---
>  include/libcamera/camera.h |  4 +++
>  src/libcamera/camera.cpp   | 68 ++++++++++++++++++++++++++++++++++++++
>  2 files changed, 72 insertions(+)
> 
> diff --git a/include/libcamera/camera.h b/include/libcamera/camera.h
> index 786d4d7d66bed5b2..798fee2487940208 100644
> --- a/include/libcamera/camera.h
> +++ b/include/libcamera/camera.h
> @@ -7,6 +7,7 @@
>  #ifndef __LIBCAMERA_CAMERA_H__
>  #define __LIBCAMERA_CAMERA_H__
>  
> +#include <map>
>  #include <memory>
>  #include <string>
>  
> @@ -16,6 +17,7 @@ namespace libcamera {
>  
>  class PipelineHandler;
>  class Stream;
> +class StreamConfiguration;
>  
>  class Camera final
>  {
> @@ -35,6 +37,8 @@ public:
>  	void release();
>  
>  	std::vector<Stream> streams() const;
> +	std::map<unsigned int, StreamConfiguration> streamConfiguration(const std::vector<Stream> &streams) const;
> +	int configureStreams(std::map<unsigned int, StreamConfiguration> &config);
>  
>  private:
>  	Camera(PipelineHandler *pipe, const std::string &name);
> diff --git a/src/libcamera/camera.cpp b/src/libcamera/camera.cpp
> index 3b2c00d0a4bb45d1..e41143972b0b537a 100644
> --- a/src/libcamera/camera.cpp
> +++ b/src/libcamera/camera.cpp
> @@ -211,4 +211,72 @@ std::vector<Stream> Camera::streams() const
>  	return streams_;
>  }
>  
> +/**
> + * \brief Retrieve a group of stream configurations
> + * \param[in] streams A map of stream IDs and configurations to setup
> + *
> + * Retrieve the camera's configuration for a specified group of streams. The
> + * caller can specify which of the camera's streams to retrieve configuration
> + * from by populating \a streams.
> + *
> + * The easiest way to populate the array of streams to fetch configuration from
> + * is to first retrieve the camera's full array of stream by with streams() and
> + * then potentially trim it down to only contain the streams the caller
> + * are interested in.
> + *
> + * \return A map of successfully retrieved stream IDs and configurations or an
> + * empty list on error.
> + */
> +std::map<unsigned int, StreamConfiguration>
> +Camera::streamConfiguration(const std::vector<Stream> &streams) const
> +{
> +	std::map<unsigned int, StreamConfiguration> config;
> +
> +	if (disconnected_ || !streams.size())
> +		return config;
> +
> +	for (const Stream &stream : streams)
> +		if (!haveStreamID(stream.id()))
> +			return config;
> +
> +	return pipe_->streamConfiguration(this, streams);
> +}
> +
> +/**
> + * \brief Configure the camera's streams prior to capture
> + * \param[in] config A map of stream IDs and configurations to setup
> + *
> + * Prior to starting capture, the camera must be configured to select a
> + * group of streams to be involved in the capture and their configuration.
> + * The caller specify which streams are to be involved and their configuration

s/specify/specifies/

> + * by populating \a config.
> + *
> + * The easiest way to populate the array of config is to fetch an initial
> + * configuration from the camera with streamConfiguration() and then change the
> + * parameters to fit the callers need and once all the streams parameters are

s/callers need/caller's needs/

> + * configured hand that over to configureStreams() to actually setup the camera.
> + *
> + * Exclusive access to the camera shall be ensured by a call to acquire() prior
> + * to calling this function, otherwise an -EACCES error is be returned.

You should document that -ENODEV will be returned in case the camera is
disconnected, and -EINVAL if the configuration isn't valid.

> + *
> + * \return 0 on success or a negative error code on error.
> + */
> +int Camera::configureStreams(std::map<unsigned int, StreamConfiguration> &config)
> +{
> +	if (disconnected_)
> +		return -ENODEV;
> +
> +	if (!acquired_)
> +		return -EACCES;
> +
> +	if (!config.size())
> +		return -EINVAL;
> +
> +	for (const auto &pair : config)
> +		if (!haveStreamID(pair.first))
> +			return -EINVAL;

Could we make this error impossible by indexing the map on a Stream
pointer ?

> +	return pipe_->configureStreams(this, config);
> +}
> +
>  } /* namespace libcamera */

-- 
Regards,

Laurent Pinchart