[libcamera-devel] [PATCH v2 05/16] libcamera: formats: Add ImageFormats

[Jacopo Mondi]

Hi Niklas,

On Wed, Jun 12, 2019 at 02:43:48AM +0200, Niklas Söderlund wrote:
> Add a new class to hold format information for v4l2 devices and
> subdevices. The object describes the relationship between either pixel
> formats (v4l2 devices) or media bus codes (v4l2 subdevice) and a list of
> image sizes which can be produced with that format.
>
> Signed-off-by: Niklas Söderlund <niklas.soderlund at ragnatech.se>
> ---
>  src/libcamera/formats.cpp       | 83 +++++++++++++++++++++++++++++++++
>  src/libcamera/include/formats.h | 17 +++++++
>  2 files changed, 100 insertions(+)
>
> diff --git a/src/libcamera/formats.cpp b/src/libcamera/formats.cpp
> index 56f4ddb51ffad4d3..ab4bae0a5928d9ba 100644
> --- a/src/libcamera/formats.cpp
> +++ b/src/libcamera/formats.cpp
> @@ -24,4 +24,87 @@ namespace libcamera {
>   * resolutions represented by SizeRange items.
>   */
>
> +/**
> + * \class ImageFormats

I'm a bit undecided here... This represents a V4L2 device or subdevice
format, and I would keep the "ImageFormats" name for the application
facing image format, which might end up being different than the V4L2
defined one.

Now that we have a V4L2Device I think V4L2Format might be considered
as an alternative name..

> + * \brief Describe V4L2Device and V4L2SubDevice image formats
> + *
> + * The class describes information about image formats and supported sizes. If
> + * the ImageFormat describe a V4L2Device the formats described are pixel formats
> + * while if it describes a V4L2SubDevice the formats are media bus codes.

I would:
 The class describes information about image formats and supported sizes. If
 the ImageFormat describe a V4L2Device the image formats are described
 with a fourcc pixel format code, while if it describes a V4L2SubDevice
 the formats are described with media bus codes, both defined by the
 V4L2 specification.

Is fine if you keep yours...

> + */
> +
> +ImageFormats::ImageFormats()
> +{
> +}

Do you need this? The compiler generates a default contructor for
you..

> +
> +/**
> + * \brief Add a format and sizes to the description
> + * \param[in] format Pixel format or media bus code to describe
> + * \param[in] sizes List of supported sizes for the format
> + *
> + * \return 0 on success or a negative error code otherwise
> + * \retval -EBUSY The format is already described
> + */
> +int ImageFormats::addFormat(unsigned int format, const std::vector<SizeRange> &sizes)
> +{
> +	if (data_.find(format) != data_.end())
> +		return -EBUSY;
> +
> +	data_[format] = sizes;
> +
> +	return 0;
> +}
> +
> +/**
> + * \brief Retrieve a list of all supported image formats
> + * \return List of pixel formats or media bus codes
> + */
> +std::vector<unsigned int> ImageFormats::formats() const
> +{
> +	std::vector<unsigned int> formats;
> +	formats.reserve(data_.size());
> +
> +	for (auto const &it : data_)
> +		formats.push_back(it.first);
> +
> +	return formats;
> +}
> +
> +/**
> + * \brief Retrieve all sizes for a specific format
> + * \param[in] format A pixelformat or mbus code
> + *
> + * Retrieve all SizeRanges for a specific format. For V4L2Device \a format is a
> + * pixel format while for a V4L2Subdevice \a format is a media bus code.
> + *
> + * \return he list of image sizes produced using \a format, or an empty list if
> + * format is not supported
> + */
> +std::vector<SizeRange> ImageFormats::sizes(unsigned int format) const
> +{
> +	auto const &it = data_.find(format);
> +	if (it == data_.end())
> +		return {};
> +
> +	return it->second;
> +}
> +
> +/**
> + * \brief Check if the list of devices supported formats is empty
> + * \return True if the list of supported formats is empty
> + */
> +bool ImageFormats::isEmpty() const
> +{
> +	return data_.empty();
> +}
> +
> +/**
> + * \brief Retrieve the map that associates formats to image sizes
> + * \return Map that associates formats to image sizes
> + */
> +const std::map<unsigned int, std::vector<SizeRange>> &ImageFormats::data() const
> +{
> +	return data_;
> +}
> +
>  } /* namespace libcamera */
> diff --git a/src/libcamera/include/formats.h b/src/libcamera/include/formats.h
> index a73772b1eda068b4..a31aa42bcb4742ac 100644
> --- a/src/libcamera/include/formats.h
> +++ b/src/libcamera/include/formats.h
> @@ -17,6 +17,23 @@ namespace libcamera {
>
>  typedef std::map<unsigned int, std::vector<SizeRange>> FormatEnum;

Do we want to use this in this class?

>
> +class ImageFormats
> +{
> +public:
> +	ImageFormats();
> +
> +	int addFormat(unsigned int format, const std::vector<SizeRange> &sizes);
> +
> +	std::vector<unsigned int> formats() const;
> +	std::vector<SizeRange> sizes(unsigned int format) const;

I would return a const & here

> +
> +	bool isEmpty() const;
> +	const std::map<unsigned int, std::vector<SizeRange>> &data() const;

and group the three data accessors together. Maybe you can move
isEmpty() up as the first method?

Thanks
   j

> +
> +private:
> +	std::map<unsigned int, std::vector<SizeRange>> data_;
> +};
> +
>  } /* namespace libcamera */
>
>  #endif /* __LIBCAMERA_FORMATS_H__ */
> --
> 2.21.0
>
> _______________________________________________
> libcamera-devel mailing list
> libcamera-devel at lists.libcamera.org
> https://lists.libcamera.org/listinfo/libcamera-devel
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