[libcamera-devel,v1.1,3/6] libcamera: color_space: Add fromString() function

17201 diff mbox series

Add a ColorSpace:fromString() function to parse a string into a color
space. The string can either contain the name of a well-known color
space, or four color space components separate by a '/' character.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Umang Jain <umang.jain@ideasonboard.com>
---
Changes since v1:

- Document the format of the color space string
---
 include/libcamera/color_space.h |   2 +
 src/libcamera/color_space.cpp   | 153 +++++++++++++++++++++++++-------
 2 files changed, 125 insertions(+), 30 deletions(-)

On Thu, Aug 25, 2022 at 12:34:14AM +0300, Laurent Pinchart via libcamera-devel wrote:
> Add a ColorSpace:fromString() function to parse a string into a color
> space. The string can either contain the name of a well-known color
> space, or four color space components separate by a '/' character.
> 
> Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> Reviewed-by: Umang Jain <umang.jain@ideasonboard.com>

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

> ---
> Changes since v1:
> 
> - Document the format of the color space string
> ---
>  include/libcamera/color_space.h |   2 +
>  src/libcamera/color_space.cpp   | 153 +++++++++++++++++++++++++-------
>  2 files changed, 125 insertions(+), 30 deletions(-)
> 
> diff --git a/include/libcamera/color_space.h b/include/libcamera/color_space.h
> index 8030a264c66f..f493f72d2db8 100644
> --- a/include/libcamera/color_space.h
> +++ b/include/libcamera/color_space.h
> @@ -59,6 +59,8 @@ public:
>  
>  	std::string toString() const;
>  	static std::string toString(const std::optional<ColorSpace> &colorSpace);
> +
> +	static std::optional<ColorSpace> fromString(const std::string &str);
>  };
>  
>  bool operator==(const ColorSpace &lhs, const ColorSpace &rhs);
> diff --git a/src/libcamera/color_space.cpp b/src/libcamera/color_space.cpp
> index 1b2dd2404452..944d0e98099b 100644
> --- a/src/libcamera/color_space.cpp
> +++ b/src/libcamera/color_space.cpp
> @@ -12,6 +12,9 @@
>  #include <map>
>  #include <sstream>
>  #include <utility>
> +#include <vector>
> +
> +#include <libcamera/base/utils.h>
>  
>  /**
>   * \file color_space.h
> @@ -208,6 +211,44 @@ const ColorSpace ColorSpace::Rec2020 = {
>   * \brief The pixel range used with by color space
>   */
>  
> +namespace {
> +
> +const std::array<std::pair<ColorSpace, const char *>, 6> colorSpaceNames = { {
> +	{ ColorSpace::Raw, "RAW" },
> +	{ ColorSpace::Srgb, "sRGB" },
> +	{ ColorSpace::Sycc, "sYCC" },
> +	{ ColorSpace::Smpte170m, "SMPTE170M" },
> +	{ ColorSpace::Rec709, "Rec709" },
> +	{ ColorSpace::Rec2020, "Rec2020" },
> +} };
> +
> +const std::map<ColorSpace::Primaries, std::string> primariesNames = {
> +	{ ColorSpace::Primaries::Raw, "RAW" },
> +	{ ColorSpace::Primaries::Smpte170m, "SMPTE170M" },
> +	{ ColorSpace::Primaries::Rec709, "Rec709" },
> +	{ ColorSpace::Primaries::Rec2020, "Rec2020" },
> +};
> +
> +const std::map<ColorSpace::TransferFunction, std::string> transferNames = {
> +	{ ColorSpace::TransferFunction::Linear, "Linear" },
> +	{ ColorSpace::TransferFunction::Srgb, "sRGB" },
> +	{ ColorSpace::TransferFunction::Rec709, "Rec709" },
> +};
> +
> +const std::map<ColorSpace::YcbcrEncoding, std::string> encodingNames = {
> +	{ ColorSpace::YcbcrEncoding::None, "None" },
> +	{ ColorSpace::YcbcrEncoding::Rec601, "Rec601" },
> +	{ ColorSpace::YcbcrEncoding::Rec709, "Rec709" },
> +	{ ColorSpace::YcbcrEncoding::Rec2020, "Rec2020" },
> +};
> +
> +const std::map<ColorSpace::Range, std::string> rangeNames = {
> +	{ ColorSpace::Range::Full, "Full" },
> +	{ ColorSpace::Range::Limited, "Limited" },
> +};
> +
> +} /* namespace */
> +
>  /**
>   * \brief Assemble and return a readable string representation of the
>   * ColorSpace
> @@ -223,14 +264,6 @@ std::string ColorSpace::toString() const
>  {
>  	/* Print out a brief name only for standard color spaces. */
>  
> -	static const std::array<std::pair<ColorSpace, const char *>, 6> colorSpaceNames = { {
> -		{ ColorSpace::Raw, "RAW" },
> -		{ ColorSpace::Srgb, "sRGB" },
> -		{ ColorSpace::Sycc, "sYCC" },
> -		{ ColorSpace::Smpte170m, "SMPTE170M" },
> -		{ ColorSpace::Rec709, "Rec709" },
> -		{ ColorSpace::Rec2020, "Rec2020" },
> -	} };
>  	auto it = std::find_if(colorSpaceNames.begin(), colorSpaceNames.end(),
>  			       [this](const auto &item) {
>  				       return *this == item.first;
> @@ -240,28 +273,6 @@ std::string ColorSpace::toString() const
>  
>  	/* Assemble a name made of the constituent fields. */
>  
> -	static const std::map<Primaries, std::string> primariesNames = {
> -		{ Primaries::Raw, "RAW" },
> -		{ Primaries::Smpte170m, "SMPTE170M" },
> -		{ Primaries::Rec709, "Rec709" },
> -		{ Primaries::Rec2020, "Rec2020" },
> -	};
> -	static const std::map<TransferFunction, std::string> transferNames = {
> -		{ TransferFunction::Linear, "Linear" },
> -		{ TransferFunction::Srgb, "sRGB" },
> -		{ TransferFunction::Rec709, "Rec709" },
> -	};
> -	static const std::map<YcbcrEncoding, std::string> encodingNames = {
> -		{ YcbcrEncoding::None, "None" },
> -		{ YcbcrEncoding::Rec601, "Rec601" },
> -		{ YcbcrEncoding::Rec709, "Rec709" },
> -		{ YcbcrEncoding::Rec2020, "Rec2020" },
> -	};
> -	static const std::map<Range, std::string> rangeNames = {
> -		{ Range::Full, "Full" },
> -		{ Range::Limited, "Limited" },
> -	};
> -
>  	auto itPrimaries = primariesNames.find(primaries);
>  	std::string primariesName =
>  		itPrimaries == primariesNames.end() ? "Invalid" : itPrimaries->second;
> @@ -303,6 +314,88 @@ std::string ColorSpace::toString(const std::optional<ColorSpace> &colorSpace)
>  	return colorSpace->toString();
>  }
>  
> +/**
> + * \brief Construct a color space from a string
> + * \param[in] str The string
> + *
> + * The string \a str can contain the name of a well-known color space, or be
> + * made of the four color space components separated by a '/' character, ordered
> + * as
> + *
> + * \verbatim primaries '/' transferFunction '/' ycbcrEncoding '/' range \endverbatim
> + *
> + * Any failure to parse the string, either because it doesn't match the expected
> + * format, or because the one of the names isn't recognized, will cause this
> + * function to return std::nullopt.
> + *
> + * \return The ColorSpace corresponding to the string, or std::nullopt if the
> + * string doesn't describe a known color space
> + */
> +std::optional<ColorSpace> ColorSpace::fromString(const std::string &str)
> +{
> +	/* First search for a standard color space name match. */
> +	auto itColorSpace = std::find_if(colorSpaceNames.begin(), colorSpaceNames.end(),
> +					 [&str](const auto &item) {
> +						 return str == item.second;
> +					 });
> +	if (itColorSpace != colorSpaceNames.end())
> +		return itColorSpace->first;
> +
> +	/*
> +	 * If not found, the string must contain the four color space
> +	 * components separated by a '/' character.
> +	 */
> +	const auto &split = utils::split(str, "/");
> +	std::vector<std::string> components{ split.begin(), split.end() };
> +
> +	if (components.size() != 4)
> +		return std::nullopt;
> +
> +	ColorSpace colorSpace = ColorSpace::Raw;
> +
> +	/* Color primaries */
> +	auto itPrimaries = std::find_if(primariesNames.begin(), primariesNames.end(),
> +					[&components](const auto &item) {
> +						return components[0] == item.second;
> +					});
> +	if (itPrimaries == primariesNames.end())
> +		return std::nullopt;
> +
> +	colorSpace.primaries = itPrimaries->first;
> +
> +	/* Transfer function */
> +	auto itTransfer = std::find_if(transferNames.begin(), transferNames.end(),
> +				       [&components](const auto &item) {
> +					       return components[1] == item.second;
> +				       });
> +	if (itTransfer == transferNames.end())
> +		return std::nullopt;
> +
> +	colorSpace.transferFunction = itTransfer->first;
> +
> +	/* YCbCr encoding */
> +	auto itEncoding = std::find_if(encodingNames.begin(), encodingNames.end(),
> +				       [&components](const auto &item) {
> +					       return components[2] == item.second;
> +				       });
> +	if (itEncoding == encodingNames.end())
> +		return std::nullopt;
> +
> +	colorSpace.ycbcrEncoding = itEncoding->first;
> +
> +	/* Quantization range */
> +	auto itRange = std::find_if(rangeNames.begin(), rangeNames.end(),
> +				    [&components](const auto &item) {
> +					    return components[3] == item.second;
> +				    });
> +	if (itRange == rangeNames.end())
> +		return std::nullopt;
> +
> +	colorSpace.range = itRange->first;
> +
> +	return colorSpace;
> +}
> +
>  /**
>   * \brief Compare color spaces for equality
>   * \return True if the two color spaces are identical, false otherwise