[libcamera-devel] [PATCH v12 7/8] libcamera: Add validateColorSpaces to CameraConfiguration class

[Jacopo Mondi]

Hi David,

On Fri, Dec 10, 2021 at 02:44:23PM +0000, David Plowman wrote:
> This function forces raw streams to have the "raw" color space, and
> also optionally makes all non-raw output streams to share the same
> color space as some platforms may require this.
>
> When sharing color spaces we take the shared value to be the one from
> the largest of these streams. This choice is ultimately arbitrary, but
> can be appropriate if smaller output streams are used for image
> analysis rather than human consumption, when the precise colours may
> be less important.
>
> Signed-off-by: David Plowman <david.plowman at raspberrypi.com>
> Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>

Reviewed-by: Jacopo Mondi <jacopo at jmondi.org>

I would have said usage of Flag<> is really an overkill, but I see
you've been suggested so, so no big deal

Thanks
   j

> ---
>  include/libcamera/camera.h | 10 +++++
>  src/libcamera/camera.cpp   | 83 ++++++++++++++++++++++++++++++++++++++
>  2 files changed, 93 insertions(+)
>
> diff --git a/include/libcamera/camera.h b/include/libcamera/camera.h
> index a7759ccb..5bb06584 100644
> --- a/include/libcamera/camera.h
> +++ b/include/libcamera/camera.h
> @@ -13,6 +13,7 @@
>  #include <string>
>
>  #include <libcamera/base/class.h>
> +#include <libcamera/base/flags.h>
>  #include <libcamera/base/object.h>
>  #include <libcamera/base/signal.h>
>
> @@ -69,6 +70,15 @@ public:
>  protected:
>  	CameraConfiguration();
>
> +	enum class ColorSpaceFlag {
> +		None,
> +		StreamsShareColorSpace,
> +	};
> +
> +	using ColorSpaceFlags = Flags<ColorSpaceFlag>;
> +
> +	Status validateColorSpaces(ColorSpaceFlags flags = ColorSpaceFlag::None);
> +
>  	std::vector<StreamConfiguration> config_;
>  };
>
> diff --git a/src/libcamera/camera.cpp b/src/libcamera/camera.cpp
> index 400a7cf0..86d84ac0 100644
> --- a/src/libcamera/camera.cpp
> +++ b/src/libcamera/camera.cpp
> @@ -14,12 +14,14 @@
>  #include <libcamera/base/log.h>
>  #include <libcamera/base/thread.h>
>
> +#include <libcamera/color_space.h>
>  #include <libcamera/framebuffer_allocator.h>
>  #include <libcamera/request.h>
>  #include <libcamera/stream.h>
>
>  #include "libcamera/internal/camera.h"
>  #include "libcamera/internal/camera_controls.h"
> +#include "libcamera/internal/formats.h"
>  #include "libcamera/internal/pipeline_handler.h"
>
>  /**
> @@ -314,6 +316,87 @@ std::size_t CameraConfiguration::size() const
>  	return config_.size();
>  }
>
> +namespace {
> +
> +bool isRaw(const PixelFormat &pixFmt)
> +{
> +	const PixelFormatInfo &info = PixelFormatInfo::info(pixFmt);
> +	return info.isValid() &&
> +	       info.colourEncoding == PixelFormatInfo::ColourEncodingRAW;
> +}
> +
> +} /* namespace */
> +
> +/**
> + * \enum CameraConfiguration::ColorSpaceFlag
> + * \brief Specify the behaviour of validateColorSpaces
> + * \var CameraConfiguration::ColorSpaceFlag::None
> + * \brief No extra validation of color spaces is required
> + * \var CameraConfiguration::ColorSpaceFlag::StreamsShareColorSpace
> + * \brief Non-raw output streams must share the same color space
> + */
> +
> +/**
> + * \typedef CameraConfiguration::ColorSpaceFlags
> + * \brief A bitwise combination of ColorSpaceFlag values
> + */
> +
> +/**
> + * \brief Check the color spaces requested for each stream
> + * \param[in] flags Flags to control the behaviour of this function
> + *
> + * This function performs certain consistency checks on the color spaces of
> + * the streams and may adjust them so that:
> + *
> + * - Any raw streams have the Raw color space
> + * - If the StreamsShareColorSpace flag is set, all output streams are forced
> + * to share the same color space (this may be a constraint on some platforms).
> + *
> + * It is optional for a pipeline handler to use this function.
> + *
> + * \return A CameraConfiguration::Status value that describes the validation
> + * status.
> + * \retval CameraConfigutation::Adjusted The configuration has been adjusted
> + * and is now valid. The color space of some or all of the streams may bave
> + * benn changed. The caller shall check the color spaces carefully.
> + * \retval CameraConfiguration::Valid The configuration was already valid and
> + * hasn't been adjusted.
> + */
> +CameraConfiguration::Status CameraConfiguration::validateColorSpaces(ColorSpaceFlags flags)
> +{
> +	Status status = Valid;
> +
> +	/*
> +	 * Set all raw streams to the Raw color space, and make a note of the largest
> +	 * non-raw stream with a defined color space (if there is one).
> +	 */
> +	int index = -1;
> +	for (auto [i, cfg] : utils::enumerate(config_)) {
> +		if (isRaw(cfg.pixelFormat)) {
> +			if (cfg.colorSpace != ColorSpace::Raw) {
> +				cfg.colorSpace = ColorSpace::Raw;
> +				status = Adjusted;
> +			}
> +		} else if (cfg.colorSpace && (index == -1 || cfg.size > config_[i].size)) {
> +			index = i;
> +		}
> +	}
> +
> +	if (index < 0 || !(flags & ColorSpaceFlag::StreamsShareColorSpace))
> +		return status;
> +
> +	/* Make all output color spaces the same, if requested. */
> +	for (auto &cfg : config_) {
> +		if (!isRaw(cfg.pixelFormat) &&
> +		    cfg.colorSpace != config_[index].colorSpace) {
> +			cfg.colorSpace = config_[index].colorSpace;
> +			status = Adjusted;
> +		}
> +	}
> +
> +	return status;
> +}
> +
>  /**
>   * \var CameraConfiguration::transform
>   * \brief User-specified transform to be applied to the image
> --
> 2.30.2
>