Improved code for constant arrays and matrices.

PiperOrigin-RevId: 435282593

Author: Material Eng

dart/lib/utils/color_utils.dart

@@ -22,6 +22,20 @@ import 'package:material_color_utilities/utils/math_utils.dart';
 /// Utility methods for color science constants and color space
 /// conversions that aren't HCT or CAM16.
 class ColorUtils {
+  static final _SRGB_TO_XYZ = [
+    [0.41233895, 0.35762064, 0.18051042],
+    [0.2126, 0.7152, 0.0722],
+    [0.01932141, 0.11916382, 0.95034478],
+  ];
+
+  static final _XYZ_TO_SRGB = [
+    [3.2406, -1.5372, -0.4986],
+    [-0.9689, 1.8758, 0.0415],
+    [0.0557, -0.204, 1.057],
+  ];
+
+  static final _WHITE_POINT_D65 = [95.047, 100.0, 108.883];
+
   /// Converts a color from RGB components to ARGB format.
   static int argbFromRgb(int red, int green, int blue) {
     return 255 << 24 | (red & 255) << 16 | (green & 255) << 8 | blue & 255;
@@ -52,27 +66,9 @@ class ColorUtils {
     return alphaFromArgb(argb) >= 255;
   }
 
-  /// Returns the sRGB to XYZ transformation matrix.
-  static List<List<double>> srgbToXyz() {
-    return [
-      [0.41233895, 0.35762064, 0.18051042],
-      [0.2126, 0.7152, 0.0722],
-      [0.01932141, 0.11916382, 0.95034478],
-    ];
-  }
-
-  /// Returns the XYZ to sRGB transformation matrix.
-  static List<List<double>> xyzToSrgb() {
-    return [
-      [3.2406, -1.5372, -0.4986],
-      [-0.9689, 1.8758, 0.0415],
-      [0.0557, -0.204, 1.057],
-    ];
-  }
-
   /// Converts a color from ARGB to XYZ.
   static int argbFromXyz(double x, double y, double z) {
-    final linearRgb = MathUtils.matrixMultiply([x, y, z], xyzToSrgb());
+    final linearRgb = MathUtils.matrixMultiply([x, y, z], _XYZ_TO_SRGB);
     final r = delinearized(linearRgb[0]);
     final g = delinearized(linearRgb[1]);
     final b = delinearized(linearRgb[2]);
@@ -84,13 +80,13 @@ class ColorUtils {
     final r = linearized(redFromArgb(argb));
     final g = linearized(greenFromArgb(argb));
     final b = linearized(blueFromArgb(argb));
-    return MathUtils.matrixMultiply([r, g, b], srgbToXyz());
+    return MathUtils.matrixMultiply([r, g, b], _SRGB_TO_XYZ);
   }
 
   /// Converts a color represented in Lab color space into an ARGB
   /// integer.
   static int argbFromLab(double l, double a, double b) {
-    final whitePoint = whitePointD65();
+    final whitePoint = _WHITE_POINT_D65;
     final fy = (l + 16.0) / 116.0;
     final fx = a / 500.0 + fy;
     final fz = fy - b / 200.0;
@@ -110,7 +106,7 @@ class ColorUtils {
   /// [argb] the ARGB representation of a color
   /// Returns a Lab object representing the color
   static List<double> labFromArgb(int argb) {
-    final whitePoint = whitePointD65();
+    final whitePoint = _WHITE_POINT_D65;
     final xyz = xyzFromArgb(argb);
     final xNormalized = xyz[0] / whitePoint[0];
     final yNormalized = xyz[1] / whitePoint[1];
@@ -141,7 +137,7 @@ class ColorUtils {
     final cubeExceedEpsilon = fy * fy * fy > epsilon;
     final x = cubeExceedEpsilon ? fx * fx * fx : lstar / kappa;
     final z = cubeExceedEpsilon ? fz * fz * fz : lstar / kappa;
-    final whitePoint = whitePointD65();
+    final whitePoint = _WHITE_POINT_D65;
     return argbFromXyz(
       x * whitePoint[0],
       y * whitePoint[1],
@@ -223,7 +219,7 @@ class ColorUtils {
   ///
   /// Returns The white point
   static List<double> whitePointD65() {
-    return [95.047, 100.0, 108.883];
+    return _WHITE_POINT_D65;
   }
 
   static double _labF(double t) {

java/utils/ColorUtils.java

@@ -27,6 +27,22 @@
 public class ColorUtils {
   private ColorUtils() {}
 
+  static final double[][] SRGB_TO_XYZ =
+      new double[][] {
+        new double[] {0.41233895, 0.35762064, 0.18051042},
+        new double[] {0.2126, 0.7152, 0.0722},
+        new double[] {0.01932141, 0.11916382, 0.95034478},
+      };
+
+  static final double[][] XYZ_TO_SRGB =
+      new double[][] {
+        new double[] {3.2406, -1.5372, -0.4986},
+        new double[] {-0.9689, 1.8758, 0.0415},
+        new double[] {0.0557, -0.204, 1.057},
+      };
+
+  static final double[] WHITE_POINT_D65 = new double[] {95.047, 100.0, 108.883};
+
   /** Converts a color from RGB components to ARGB format. */
   public static int argbFromRgb(int red, int green, int blue) {
     return (255 << 24) | ((red & 255) << 16) | ((green & 255) << 8) | (blue & 255);
@@ -57,27 +73,9 @@ public static boolean isOpaque(int argb) {
     return alphaFromArgb(argb) >= 255;
   }
 
-  /** Returns the sRGB to XYZ transformation matrix. */
-  public static double[][] srgbToXyz() {
-    return new double[][] {
-      new double[] {0.41233895, 0.35762064, 0.18051042},
-      new double[] {0.2126, 0.7152, 0.0722},
-      new double[] {0.01932141, 0.11916382, 0.95034478},
-    };
-  }
-
-  /** Returns the XYZ to sRGB transformation matrix. */
-  public static double[][] xyzToSrgb() {
-    return new double[][] {
-      new double[] {3.2406, -1.5372, -0.4986},
-      new double[] {-0.9689, 1.8758, 0.0415},
-      new double[] {0.0557, -0.204, 1.057},
-    };
-  }
-
   /** Converts a color from ARGB to XYZ. */
   public static int argbFromXyz(double x, double y, double z) {
-    double[] linearRgb = MathUtils.matrixMultiply(new double[] {x, y, z}, xyzToSrgb());
+    double[] linearRgb = MathUtils.matrixMultiply(new double[] {x, y, z}, XYZ_TO_SRGB);
     int r = delinearized(linearRgb[0]);
     int g = delinearized(linearRgb[1]);
     int b = delinearized(linearRgb[2]);
@@ -89,12 +87,12 @@ public static double[] xyzFromArgb(int argb) {
     double r = linearized(redFromArgb(argb));
     double g = linearized(greenFromArgb(argb));
     double b = linearized(blueFromArgb(argb));
-    return MathUtils.matrixMultiply(new double[] {r, g, b}, srgbToXyz());
+    return MathUtils.matrixMultiply(new double[] {r, g, b}, SRGB_TO_XYZ);
   }
 
   /** Converts a color represented in Lab color space into an ARGB integer. */
   public static int argbFromLab(double l, double a, double b) {
-    double[] whitePoint = whitePointD65();
+    double[] whitePoint = WHITE_POINT_D65;
     double fy = (l + 16.0) / 116.0;
     double fx = a / 500.0 + fy;
     double fz = fy - b / 200.0;
@@ -114,7 +112,7 @@ public static int argbFromLab(double l, double a, double b) {
    * @return a Lab object representing the color
    */
   public static double[] labFromArgb(int argb) {
-    double[] whitePoint = whitePointD65();
+    double[] whitePoint = WHITE_POINT_D65;
     double[] xyz = xyzFromArgb(argb);
     double xNormalized = xyz[0] / whitePoint[0];
     double yNormalized = xyz[1] / whitePoint[1];
@@ -145,7 +143,7 @@ public static int argbFromLstar(double lstar) {
     boolean cubeExceedEpsilon = fy * fy * fy > epsilon;
     double x = cubeExceedEpsilon ? fx * fx * fx : lstar / kappa;
     double z = cubeExceedEpsilon ? fz * fz * fz : lstar / kappa;
-    double[] whitePoint = whitePointD65();
+    double[] whitePoint = WHITE_POINT_D65;
     return argbFromXyz(x * whitePoint[0], y * whitePoint[1], z * whitePoint[2]);
   }
 
@@ -224,7 +222,7 @@ public static int delinearized(double rgbComponent) {
    * @return The white point
    */
   public static double[] whitePointD65() {
-    return new double[] {95.047, 100.0, 108.883};
+    return WHITE_POINT_D65;
   }
 
   static double labF(double t) {

typescript/utils/color_utils.ts

@@ -26,6 +26,20 @@ import * as mathUtils from './math_utils';
  *  conversions that aren't HCT or CAM16.
  */
 
+const SRGB_TO_XYZ = [
+  [0.41233895, 0.35762064, 0.18051042],
+  [0.2126, 0.7152, 0.0722],
+  [0.01932141, 0.11916382, 0.95034478],
+];
+
+const XYZ_TO_SRGB = [
+  [3.2406, -1.5372, -0.4986],
+  [-0.9689, 1.8758, 0.0415],
+  [0.0557, -0.204, 1.057],
+];
+
+const WHITE_POINT_D65 = [95.047, 100.0, 108.883];
+
 /**
  * Converts a color from RGB components to ARGB format.
  */
@@ -69,33 +83,11 @@ export function isOpaque(argb: number): boolean {
   return alphaFromArgb(argb) >= 255;
 }
 
-/**
- * Returns the sRGB to XYZ transformation matrix.
- */
-export function srgbToXyz(): number[][] {
-  return [
-    [0.41233895, 0.35762064, 0.18051042],
-    [0.2126, 0.7152, 0.0722],
-    [0.01932141, 0.11916382, 0.95034478],
-  ];
-}
-
-/**
- * Returns the XYZ to sRGB transformation matrix.
- */
-export function xyzToSrgb(): number[][] {
-  return [
-    [3.2406, -1.5372, -0.4986],
-    [-0.9689, 1.8758, 0.0415],
-    [0.0557, -0.204, 1.057],
-  ];
-}
-
 /**
  * Converts a color from ARGB to XYZ.
  */
 export function argbFromXyz(x: number, y: number, z: number): number {
-  const linearRgb = mathUtils.matrixMultiply([x, y, z], xyzToSrgb());
+  const linearRgb = mathUtils.matrixMultiply([x, y, z], XYZ_TO_SRGB);
   const r = delinearized(linearRgb[0]);
   const g = delinearized(linearRgb[1]);
   const b = delinearized(linearRgb[2]);
@@ -109,15 +101,15 @@ export function xyzFromArgb(argb: number): number[] {
   const r = linearized(redFromArgb(argb));
   const g = linearized(greenFromArgb(argb));
   const b = linearized(blueFromArgb(argb));
-  return mathUtils.matrixMultiply([r, g, b], srgbToXyz());
+  return mathUtils.matrixMultiply([r, g, b], SRGB_TO_XYZ);
 }
 
 /**
  * Converts a color represented in Lab color space into an ARGB
  *  integer.
  */
 export function argbFromLab(l: number, a: number, b: number): number {
-  const whitePoint = whitePointD65();
+  const whitePoint = WHITE_POINT_D65;
   const fy = (l + 16.0) / 116.0;
   const fx = a / 500.0 + fy;
   const fz = fy - b / 200.0;
@@ -139,7 +131,7 @@ export function argbFromLab(l: number, a: number, b: number): number {
  *  @return a Lab object representing the color
  */
 export function labFromArgb(argb: number): number[] {
-  const whitePoint = whitePointD65();
+  const whitePoint = WHITE_POINT_D65;
   const xyz = xyzFromArgb(argb);
   const xNormalized = xyz[0] / whitePoint[0];
   const yNormalized = xyz[1] / whitePoint[1];
@@ -172,7 +164,7 @@ export function argbFromLstar(lstar: number): number {
   const cubeExceedEpsilon = fy * fy * fy > epsilon;
   const x = cubeExceedEpsilon ? fx * fx * fx : lstar / kappa;
   const z = cubeExceedEpsilon ? fz * fz * fz : lstar / kappa;
-  const whitePoint = whitePointD65();
+  const whitePoint = WHITE_POINT_D65;
   return argbFromXyz(
       x * whitePoint[0],
       y * whitePoint[1],
@@ -264,7 +256,7 @@ export function delinearized(rgbComponent: number): number {
  *  @return The white point
  */
 export function whitePointD65(): number[] {
-  return [95.047, 100.0, 108.883];
+  return WHITE_POINT_D65;
 }
 
 function labF(t: number): number {