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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* HSLuv-C: Human-friendly HSL
*
* Authors:
* 2015 Alexei Boronine (original idea, JavaScript implementation)
* 2015 Roger Tallada (Obj-C implementation)
* 2017 Martin Mitas (C implementation, based on Obj-C implementation)
* 2021 Massinissa Derriche (C++ implementation for Inkscape, based on C implementation)
*
* Copyright (C) 2021 Authors
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
* IN THE SOFTWARE.
*/
#ifndef SEEN_HSLUV_H
#define SEEN_HSLUV_H
#include <array>
#include <2geom/line.h>
namespace Hsluv {
// Types
using Triplet = std::array<double, 3>;
/**
* Used to represent the in RGB gamut colors polygon of the HSLuv color wheel.
*/
struct PickerGeometry {
std::vector<Geom::Point> vertices; ///< Vertices, in counter-clockwise order.
double outer_circle_radius; ///< Smallest circle with center at origin such that polygon fits inside.
double inner_circle_radius; ///< Largest circle with center at origin such that it fits inside polygon.
};
// Functions
/** Apply sRGB gamma compression to a linear RGB color component. */
double from_linear(double c);
/** Convert an sRGB color component to linear RGB (de-gamma). */
double to_linear(double c);
/**
* Return the bounds of the Luv colors in RGB gamut.
*
* @param l Lightness. Between 0.0 and 100.0.
* @return Bounds of Luv colors in RGB gamut.
*/
std::array<Geom::Line, 6> get_bounds(double l);
/**
* Convert Luv to RGB.
*
* @param l Luminance. Between 0.0 and 100.0.
* @param u U coordinate.
* @param v V coordinate.
* @return An RGB triplet, with all components between 0.0 and 1.0.
*/
Triplet luv_to_rgb(double l, double u, double v);
/**
* Convert HSLuv to Luv.
*
* @param hsl A pointer to a buffer of length 3 containing an HSLuv color:
* [0]: Hue between 0.0 and 360.0.
* [1]: Saturation between 0.0 and 100.0.
* [2]: Lightness between 0.0 and 100.0.
* @return An LUV triplet, with luminance between 0.0 and 100.0.
*/
Triplet hsluv_to_luv(double *hsl);
/**
* Convert Luv to HSLuv.
*
* @param l Luminance. Between 0.0 and 100.0.
* @param u U coordinate.
* @param v V coordinate.
* @return An HSLuv triplet containing:
* [0]: Hue between 0.0 and 360.0;
* [1]: Saturation between 0.0 and 100.0;
* [2]: Lightness between 0.0 and 100.0.
*/
Triplet luv_to_hsluv(double l, double u, double v);
/**
* Convert RGB to HSLuv.
*
* @param r Red. Between 0.0 and 1.0.
* @param g Green. Between 0.0 and 1.0.
* @param b Blue. Between 0.0 and 1.0.
* @return An HSLuv triplet containing:
* [0]: Hue between 0.0 and 360.0;
* [1]: Saturation between 0.0 and 100.0;
* [2]: Lightness between 0.0 and 100.0.
*/
Triplet rgb_to_hsluv(double r, double g, double b);
/**
* Convert HSLuv to RGB.
*
* @param h Hue. Between 0.0 and 360.0.
* @param s Saturation. Between 0.0 and 100.0.
* @param l Lightness. Between 0.0 and 100.0.
* @return An RGB triplet, with all components between 0.0 and 1.0.
*/
Triplet hsluv_to_rgb(double h, double s, double l);
/**
* Calculate the perceptual lightness of an HSLuv color.
*
* @param l The lightness component in HSLuv coordinates, between 0.0 and 100.0.
* @return The perceptual lightness between 0.0 (black) and 1.0 (white).
*/
double perceptual_lightness(double l);
/**
* Calculate the perceptual lightness of an RGB color.
*
* @param rgb A triplet of RGB components between 0.0 and 1.0.
* @return The perceptual lightness between 0.0 (black) and 1.0 (white).
*/
double rgb_to_perceptual_lightness(Triplet const &rgb);
/**
* Get a contrasting grayscale color suitable for UI elements shown against
* a background color with the specified perceptual lightness.
*
* @param perceptual_lightness The perceptual lightness of the background, between 0.0 and 1.0.
* @return A pair consisting of grayscale and alpha components representing a color which will
* be easy to spot against the background. Both components are between 0.0 and 1.0.
*/
std::pair<double, double> get_contrasting_color(double perceptual_lightness);
} // namespace Hsluv
#endif // SEEN_HSLUV_H
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