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Diffstat (limited to 'hct/HctSolver.java')
| -rw-r--r-- | hct/HctSolver.java | 672 |
1 files changed, 672 insertions, 0 deletions
diff --git a/hct/HctSolver.java b/hct/HctSolver.java new file mode 100644 index 0000000..b64c36e --- /dev/null +++ b/hct/HctSolver.java @@ -0,0 +1,672 @@ +/* + * Copyright 2021 Google LLC + * + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +// This file is automatically generated. Do not modify it. + +package com.google.ux.material.libmonet.hct; + +import com.google.ux.material.libmonet.utils.ColorUtils; +import com.google.ux.material.libmonet.utils.MathUtils; + +/** A class that solves the HCT equation. */ +public class HctSolver { + private HctSolver() {} + + static final double[][] SCALED_DISCOUNT_FROM_LINRGB = + new double[][] { + new double[] { + 0.001200833568784504, 0.002389694492170889, 0.0002795742885861124, + }, + new double[] { + 0.0005891086651375999, 0.0029785502573438758, 0.0003270666104008398, + }, + new double[] { + 0.00010146692491640572, 0.0005364214359186694, 0.0032979401770712076, + }, + }; + + static final double[][] LINRGB_FROM_SCALED_DISCOUNT = + new double[][] { + new double[] { + 1373.2198709594231, -1100.4251190754821, -7.278681089101213, + }, + new double[] { + -271.815969077903, 559.6580465940733, -32.46047482791194, + }, + new double[] { + 1.9622899599665666, -57.173814538844006, 308.7233197812385, + }, + }; + + static final double[] Y_FROM_LINRGB = new double[] {0.2126, 0.7152, 0.0722}; + + static final double[] CRITICAL_PLANES = + new double[] { + 0.015176349177441876, + 0.045529047532325624, + 0.07588174588720938, + 0.10623444424209313, + 0.13658714259697685, + 0.16693984095186062, + 0.19729253930674434, + 0.2276452376616281, + 0.2579979360165119, + 0.28835063437139563, + 0.3188300904430532, + 0.350925934958123, + 0.3848314933096426, + 0.42057480301049466, + 0.458183274052838, + 0.4976837250274023, + 0.5391024159806381, + 0.5824650784040898, + 0.6277969426914107, + 0.6751227633498623, + 0.7244668422128921, + 0.775853049866786, + 0.829304845476233, + 0.8848452951698498, + 0.942497089126609, + 1.0022825574869039, + 1.0642236851973577, + 1.1283421258858297, + 1.1946592148522128, + 1.2631959812511864, + 1.3339731595349034, + 1.407011200216447, + 1.4823302800086415, + 1.5599503113873272, + 1.6398909516233677, + 1.7221716113234105, + 1.8068114625156377, + 1.8938294463134073, + 1.9832442801866852, + 2.075074464868551, + 2.1693382909216234, + 2.2660538449872063, + 2.36523901573795, + 2.4669114995532007, + 2.5710888059345764, + 2.6777882626779785, + 2.7870270208169257, + 2.898822059350997, + 3.0131901897720907, + 3.1301480604002863, + 3.2497121605402226, + 3.3718988244681087, + 3.4967242352587946, + 3.624204428461639, + 3.754355295633311, + 3.887192587735158, + 4.022731918402185, + 4.160988767090289, + 4.301978482107941, + 4.445716283538092, + 4.592217266055746, + 4.741496401646282, + 4.893568542229298, + 5.048448422192488, + 5.20615066083972, + 5.3666897647573375, + 5.5300801301023865, + 5.696336044816294, + 5.865471690767354, + 6.037501145825082, + 6.212438385869475, + 6.390297286737924, + 6.571091626112461, + 6.7548350853498045, + 6.941541251256611, + 7.131223617812143, + 7.323895587840543, + 7.5195704746346665, + 7.7182615035334345, + 7.919981813454504, + 8.124744458384042, + 8.332562408825165, + 8.543448553206703, + 8.757415699253682, + 8.974476575321063, + 9.194643831691977, + 9.417930041841839, + 9.644347703669503, + 9.873909240696694, + 10.106627003236781, + 10.342513269534024, + 10.58158024687427, + 10.8238400726681, + 11.069304815507364, + 11.317986476196008, + 11.569896988756009, + 11.825048221409341, + 12.083451977536606, + 12.345119996613247, + 12.610063955123938, + 12.878295467455942, + 13.149826086772048, + 13.42466730586372, + 13.702830557985108, + 13.984327217668513, + 14.269168601521828, + 14.55736596900856, + 14.848930523210871, + 15.143873411576273, + 15.44220572664832, + 15.743938506781891, + 16.04908273684337, + 16.35764934889634, + 16.66964922287304, + 16.985093187232053, + 17.30399201960269, + 17.62635644741625, + 17.95219714852476, + 18.281524751807332, + 18.614349837764564, + 18.95068293910138, + 19.290534541298456, + 19.633915083172692, + 19.98083495742689, + 20.331304511189067, + 20.685334046541502, + 21.042933821039977, + 21.404114048223256, + 21.76888489811322, + 22.137256497705877, + 22.50923893145328, + 22.884842241736916, + 23.264076429332462, + 23.6469514538663, + 24.033477234264016, + 24.42366364919083, + 24.817520537484558, + 25.21505769858089, + 25.61628489293138, + 26.021211842414342, + 26.429848230738664, + 26.842203703840827, + 27.258287870275353, + 27.678110301598522, + 28.10168053274597, + 28.529008062403893, + 28.96010235337422, + 29.39497283293396, + 29.83362889318845, + 30.276079891419332, + 30.722335150426627, + 31.172403958865512, + 31.62629557157785, + 32.08401920991837, + 32.54558406207592, + 33.010999283389665, + 33.4802739966603, + 33.953417292456834, + 34.430438229418264, + 34.911345834551085, + 35.39614910352207, + 35.88485700094671, + 36.37747846067349, + 36.87402238606382, + 37.37449765026789, + 37.87891309649659, + 38.38727753828926, + 38.89959975977785, + 39.41588851594697, + 39.93615253289054, + 40.460400508064545, + 40.98864111053629, + 41.520882981230194, + 42.05713473317016, + 42.597404951718396, + 43.141702194811224, + 43.6900349931913, + 44.24241185063697, + 44.798841244188324, + 45.35933162437017, + 45.92389141541209, + 46.49252901546552, + 47.065252796817916, + 47.64207110610409, + 48.22299226451468, + 48.808024568002054, + 49.3971762874833, + 49.9904556690408, + 50.587870934119984, + 51.189430279724725, + 51.79514187861014, + 52.40501387947288, + 53.0190544071392, + 53.637271562750364, + 54.259673423945976, + 54.88626804504493, + 55.517063457223934, + 56.15206766869424, + 56.79128866487574, + 57.43473440856916, + 58.08241284012621, + 58.734331877617365, + 59.39049941699807, + 60.05092333227251, + 60.715611475655585, + 61.38457167773311, + 62.057811747619894, + 62.7353394731159, + 63.417162620860914, + 64.10328893648692, + 64.79372614476921, + 65.48848194977529, + 66.18756403501224, + 66.89098006357258, + 67.59873767827808, + 68.31084450182222, + 69.02730813691093, + 69.74813616640164, + 70.47333615344107, + 71.20291564160104, + 71.93688215501312, + 72.67524319850172, + 73.41800625771542, + 74.16517879925733, + 74.9167682708136, + 75.67278210128072, + 76.43322770089146, + 77.1981124613393, + 77.96744375590167, + 78.74122893956174, + 79.51947534912904, + 80.30219030335869, + 81.08938110306934, + 81.88105503125999, + 82.67721935322541, + 83.4778813166706, + 84.28304815182372, + 85.09272707154808, + 85.90692527145302, + 86.72564993000343, + 87.54890820862819, + 88.3767072518277, + 89.2090541872801, + 90.04595612594655, + 90.88742016217518, + 91.73345337380438, + 92.58406282226491, + 93.43925555268066, + 94.29903859396902, + 95.16341895893969, + 96.03240364439274, + 96.9059996312159, + 97.78421388448044, + 98.6670533535366, + 99.55452497210776, + }; + + /** + * Sanitizes a small enough angle in radians. + * + * @param angle An angle in radians; must not deviate too much from 0. + * @return A coterminal angle between 0 and 2pi. + */ + static double sanitizeRadians(double angle) { + return (angle + Math.PI * 8) % (Math.PI * 2); + } + + /** + * Delinearizes an RGB component, returning a floating-point number. + * + * @param rgbComponent 0.0 <= rgb_component <= 100.0, represents linear R/G/B channel + * @return 0.0 <= output <= 255.0, color channel converted to regular RGB space + */ + static double trueDelinearized(double rgbComponent) { + double normalized = rgbComponent / 100.0; + double delinearized = 0.0; + if (normalized <= 0.0031308) { + delinearized = normalized * 12.92; + } else { + delinearized = 1.055 * Math.pow(normalized, 1.0 / 2.4) - 0.055; + } + return delinearized * 255.0; + } + + static double chromaticAdaptation(double component) { + double af = Math.pow(Math.abs(component), 0.42); + return MathUtils.signum(component) * 400.0 * af / (af + 27.13); + } + + /** + * Returns the hue of a linear RGB color in CAM16. + * + * @param linrgb The linear RGB coordinates of a color. + * @return The hue of the color in CAM16, in radians. + */ + static double hueOf(double[] linrgb) { + double[] scaledDiscount = MathUtils.matrixMultiply(linrgb, SCALED_DISCOUNT_FROM_LINRGB); + double rA = chromaticAdaptation(scaledDiscount[0]); + double gA = chromaticAdaptation(scaledDiscount[1]); + double bA = chromaticAdaptation(scaledDiscount[2]); + // redness-greenness + double a = (11.0 * rA + -12.0 * gA + bA) / 11.0; + // yellowness-blueness + double b = (rA + gA - 2.0 * bA) / 9.0; + return Math.atan2(b, a); + } + + static boolean areInCyclicOrder(double a, double b, double c) { + double deltaAB = sanitizeRadians(b - a); + double deltaAC = sanitizeRadians(c - a); + return deltaAB < deltaAC; + } + + /** + * Solves the lerp equation. + * + * @param source The starting number. + * @param mid The number in the middle. + * @param target The ending number. + * @return A number t such that lerp(source, target, t) = mid. + */ + static double intercept(double source, double mid, double target) { + return (mid - source) / (target - source); + } + + static double[] lerpPoint(double[] source, double t, double[] target) { + return new double[] { + source[0] + (target[0] - source[0]) * t, + source[1] + (target[1] - source[1]) * t, + source[2] + (target[2] - source[2]) * t, + }; + } + + /** + * Intersects a segment with a plane. + * + * @param source The coordinates of point A. + * @param coordinate The R-, G-, or B-coordinate of the plane. + * @param target The coordinates of point B. + * @param axis The axis the plane is perpendicular with. (0: R, 1: G, 2: B) + * @return The intersection point of the segment AB with the plane R=coordinate, G=coordinate, or + * B=coordinate + */ + static double[] setCoordinate(double[] source, double coordinate, double[] target, int axis) { + double t = intercept(source[axis], coordinate, target[axis]); + return lerpPoint(source, t, target); + } + + static boolean isBounded(double x) { + return 0.0 <= x && x <= 100.0; + } + + /** + * Returns the nth possible vertex of the polygonal intersection. + * + * @param y The Y value of the plane. + * @param n The zero-based index of the point. 0 <= n <= 11. + * @return The nth possible vertex of the polygonal intersection of the y plane and the RGB cube, + * in linear RGB coordinates, if it exists. If this possible vertex lies outside of the cube, + * [-1.0, -1.0, -1.0] is returned. + */ + static double[] nthVertex(double y, int n) { + double kR = Y_FROM_LINRGB[0]; + double kG = Y_FROM_LINRGB[1]; + double kB = Y_FROM_LINRGB[2]; + double coordA = n % 4 <= 1 ? 0.0 : 100.0; + double coordB = n % 2 == 0 ? 0.0 : 100.0; + if (n < 4) { + double g = coordA; + double b = coordB; + double r = (y - g * kG - b * kB) / kR; + if (isBounded(r)) { + return new double[] {r, g, b}; + } else { + return new double[] {-1.0, -1.0, -1.0}; + } + } else if (n < 8) { + double b = coordA; + double r = coordB; + double g = (y - r * kR - b * kB) / kG; + if (isBounded(g)) { + return new double[] {r, g, b}; + } else { + return new double[] {-1.0, -1.0, -1.0}; + } + } else { + double r = coordA; + double g = coordB; + double b = (y - r * kR - g * kG) / kB; + if (isBounded(b)) { + return new double[] {r, g, b}; + } else { + return new double[] {-1.0, -1.0, -1.0}; + } + } + } + + /** + * Finds the segment containing the desired color. + * + * @param y The Y value of the color. + * @param targetHue The hue of the color. + * @return A list of two sets of linear RGB coordinates, each corresponding to an endpoint of the + * segment containing the desired color. + */ + static double[][] bisectToSegment(double y, double targetHue) { + double[] left = new double[] {-1.0, -1.0, -1.0}; + double[] right = left; + double leftHue = 0.0; + double rightHue = 0.0; + boolean initialized = false; + boolean uncut = true; + for (int n = 0; n < 12; n++) { + double[] mid = nthVertex(y, n); + if (mid[0] < 0) { + continue; + } + double midHue = hueOf(mid); + if (!initialized) { + left = mid; + right = mid; + leftHue = midHue; + rightHue = midHue; + initialized = true; + continue; + } + if (uncut || areInCyclicOrder(leftHue, midHue, rightHue)) { + uncut = false; + if (areInCyclicOrder(leftHue, targetHue, midHue)) { + right = mid; + rightHue = midHue; + } else { + left = mid; + leftHue = midHue; + } + } + } + return new double[][] {left, right}; + } + + static double[] midpoint(double[] a, double[] b) { + return new double[] { + (a[0] + b[0]) / 2, (a[1] + b[1]) / 2, (a[2] + b[2]) / 2, + }; + } + + static int criticalPlaneBelow(double x) { + return (int) Math.floor(x - 0.5); + } + + static int criticalPlaneAbove(double x) { + return (int) Math.ceil(x - 0.5); + } + + /** + * Finds a color with the given Y and hue on the boundary of the cube. + * + * @param y The Y value of the color. + * @param targetHue The hue of the color. + * @return The desired color, in linear RGB coordinates. + */ + static double[] bisectToLimit(double y, double targetHue) { + double[][] segment = bisectToSegment(y, targetHue); + double[] left = segment[0]; + double leftHue = hueOf(left); + double[] right = segment[1]; + for (int axis = 0; axis < 3; axis++) { + if (left[axis] != right[axis]) { + int lPlane = -1; + int rPlane = 255; + if (left[axis] < right[axis]) { + lPlane = criticalPlaneBelow(trueDelinearized(left[axis])); + rPlane = criticalPlaneAbove(trueDelinearized(right[axis])); + } else { + lPlane = criticalPlaneAbove(trueDelinearized(left[axis])); + rPlane = criticalPlaneBelow(trueDelinearized(right[axis])); + } + for (int i = 0; i < 8; i++) { + if (Math.abs(rPlane - lPlane) <= 1) { + break; + } else { + int mPlane = (int) Math.floor((lPlane + rPlane) / 2.0); + double midPlaneCoordinate = CRITICAL_PLANES[mPlane]; + double[] mid = setCoordinate(left, midPlaneCoordinate, right, axis); + double midHue = hueOf(mid); + if (areInCyclicOrder(leftHue, targetHue, midHue)) { + right = mid; + rPlane = mPlane; + } else { + left = mid; + leftHue = midHue; + lPlane = mPlane; + } + } + } + } + } + return midpoint(left, right); + } + + static double inverseChromaticAdaptation(double adapted) { + double adaptedAbs = Math.abs(adapted); + double base = Math.max(0, 27.13 * adaptedAbs / (400.0 - adaptedAbs)); + return MathUtils.signum(adapted) * Math.pow(base, 1.0 / 0.42); + } + + /** + * Finds a color with the given hue, chroma, and Y. + * + * @param hueRadians The desired hue in radians. + * @param chroma The desired chroma. + * @param y The desired Y. + * @return The desired color as a hexadecimal integer, if found; 0 otherwise. + */ + static int findResultByJ(double hueRadians, double chroma, double y) { + // Initial estimate of j. + double j = Math.sqrt(y) * 11.0; + // =========================================================== + // Operations inlined from Cam16 to avoid repeated calculation + // =========================================================== + ViewingConditions viewingConditions = ViewingConditions.DEFAULT; + double tInnerCoeff = 1 / Math.pow(1.64 - Math.pow(0.29, viewingConditions.getN()), 0.73); + double eHue = 0.25 * (Math.cos(hueRadians + 2.0) + 3.8); + double p1 = eHue * (50000.0 / 13.0) * viewingConditions.getNc() * viewingConditions.getNcb(); + double hSin = Math.sin(hueRadians); + double hCos = Math.cos(hueRadians); + for (int iterationRound = 0; iterationRound < 5; iterationRound++) { + // =========================================================== + // Operations inlined from Cam16 to avoid repeated calculation + // =========================================================== + double jNormalized = j / 100.0; + double alpha = chroma == 0.0 || j == 0.0 ? 0.0 : chroma / Math.sqrt(jNormalized); + double t = Math.pow(alpha * tInnerCoeff, 1.0 / 0.9); + double ac = + viewingConditions.getAw() + * Math.pow(jNormalized, 1.0 / viewingConditions.getC() / viewingConditions.getZ()); + double p2 = ac / viewingConditions.getNbb(); + double gamma = 23.0 * (p2 + 0.305) * t / (23.0 * p1 + 11 * t * hCos + 108.0 * t * hSin); + double a = gamma * hCos; + double b = gamma * hSin; + double rA = (460.0 * p2 + 451.0 * a + 288.0 * b) / 1403.0; + double gA = (460.0 * p2 - 891.0 * a - 261.0 * b) / 1403.0; + double bA = (460.0 * p2 - 220.0 * a - 6300.0 * b) / 1403.0; + double rCScaled = inverseChromaticAdaptation(rA); + double gCScaled = inverseChromaticAdaptation(gA); + double bCScaled = inverseChromaticAdaptation(bA); + double[] linrgb = + MathUtils.matrixMultiply( + new double[] {rCScaled, gCScaled, bCScaled}, LINRGB_FROM_SCALED_DISCOUNT); + // =========================================================== + // Operations inlined from Cam16 to avoid repeated calculation + // =========================================================== + if (linrgb[0] < 0 || linrgb[1] < 0 || linrgb[2] < 0) { + return 0; + } + double kR = Y_FROM_LINRGB[0]; + double kG = Y_FROM_LINRGB[1]; + double kB = Y_FROM_LINRGB[2]; + double fnj = kR * linrgb[0] + kG * linrgb[1] + kB * linrgb[2]; + if (fnj <= 0) { + return 0; + } + if (iterationRound == 4 || Math.abs(fnj - y) < 0.002) { + if (linrgb[0] > 100.01 || linrgb[1] > 100.01 || linrgb[2] > 100.01) { + return 0; + } + return ColorUtils.argbFromLinrgb(linrgb); + } + // Iterates with Newton method, + // Using 2 * fn(j) / j as the approximation of fn'(j) + j = j - (fnj - y) * j / (2 * fnj); + } + return 0; + } + + /** + * Finds an sRGB color with the given hue, chroma, and L*, if possible. + * + * @param hueDegrees The desired hue, in degrees. + * @param chroma The desired chroma. + * @param lstar The desired L*. + * @return A hexadecimal representing the sRGB color. The color has sufficiently close hue, + * chroma, and L* to the desired values, if possible; otherwise, the hue and L* will be + * sufficiently close, and chroma will be maximized. + */ + public static int solveToInt(double hueDegrees, double chroma, double lstar) { + if (chroma < 0.0001 || lstar < 0.0001 || lstar > 99.9999) { + return ColorUtils.argbFromLstar(lstar); + } + hueDegrees = MathUtils.sanitizeDegreesDouble(hueDegrees); + double hueRadians = hueDegrees / 180 * Math.PI; + double y = ColorUtils.yFromLstar(lstar); + int exactAnswer = findResultByJ(hueRadians, chroma, y); + if (exactAnswer != 0) { + return exactAnswer; + } + double[] linrgb = bisectToLimit(y, hueRadians); + return ColorUtils.argbFromLinrgb(linrgb); + } + + /** + * Finds an sRGB color with the given hue, chroma, and L*, if possible. + * + * @param hueDegrees The desired hue, in degrees. + * @param chroma The desired chroma. + * @param lstar The desired L*. + * @return A CAM16 object representing the sRGB color. The color has sufficiently close hue, + * chroma, and L* to the desired values, if possible; otherwise, the hue and L* will be + * sufficiently close, and chroma will be maximized. + */ + public static Cam16 solveToCam(double hueDegrees, double chroma, double lstar) { + return Cam16.fromInt(solveToInt(hueDegrees, chroma, lstar)); + } +} + |