From 23c8d40ad009ee9bbd1259c9450c897864ade253 Mon Sep 17 00:00:00 2001
From: Looly <loolly@gmail.com>
Date: Thu, 15 Sep 2022 02:08:14 +0800
Subject: [PATCH] add LabColor

---
 .../java/cn/hutool/swing/img/LabColor.java    | 91 +++++++++++++++++++
 1 file changed, 91 insertions(+)
 create mode 100644 hutool-swing/src/main/java/cn/hutool/swing/img/LabColor.java

diff --git a/hutool-swing/src/main/java/cn/hutool/swing/img/LabColor.java b/hutool-swing/src/main/java/cn/hutool/swing/img/LabColor.java
new file mode 100644
index 000000000..8be48d4c2
--- /dev/null
+++ b/hutool-swing/src/main/java/cn/hutool/swing/img/LabColor.java
@@ -0,0 +1,91 @@
+package cn.hutool.swing.img;
+
+import cn.hutool.core.lang.Assert;
+
+import java.awt.Color;
+import java.awt.color.ColorSpace;
+
+/**
+ * 表示以 LAB 形式存储的颜色。<br>
+ * <ul>
+ *     <li>L: 亮度</li>
+ *     <li>a: 正数代表红色，负端代表绿色</li>
+ *     <li>b: 正数代表黄色，负端代表蓝色</li>
+ * </ul>
+ *
+ * @author Tom Xin
+ * @since 5.8.7
+ */
+public class LabColor {
+
+	private static final ColorSpace XYZ_COLOR_SPACE = ColorSpace.getInstance(ColorSpace.CS_CIEXYZ);
+
+	/**
+	 * L: 亮度
+	 */
+	private final double l;
+	/**
+	 * A: 正数代表红色，负端代表绿色
+	 */
+	private final double a;
+	/**
+	 * B: 正数代表黄色，负端代表蓝色
+	 */
+	private final double b;
+
+	public LabColor(Integer rgb) {
+		this((rgb != null) ? new Color(rgb) : null);
+	}
+
+	public LabColor(Color color) {
+		Assert.notNull(color, "Color must not be null");
+		final float[] lab = fromXyz(color.getColorComponents(XYZ_COLOR_SPACE, null));
+		this.l = lab[0];
+		this.a = lab[1];
+		this.b = lab[2];
+	}
+
+	/**
+	 * 获取颜色差
+	 *
+	 * @param other 其他Lab颜色
+	 * @return 颜色差
+	 */
+	// See https://en.wikipedia.org/wiki/Color_difference#CIE94
+	public double getDistance(LabColor other) {
+		double c1 = Math.sqrt(this.a * this.a + this.b * this.b);
+		double deltaC = c1 - Math.sqrt(other.a * other.a + other.b * other.b);
+		double deltaA = this.a - other.a;
+		double deltaB = this.b - other.b;
+		double deltaH = Math.sqrt(Math.max(0.0, deltaA * deltaA + deltaB * deltaB - deltaC * deltaC));
+		return Math.sqrt(Math.max(0.0, Math.pow((this.l - other.l), 2)
+				+ Math.pow(deltaC / (1 + 0.045 * c1), 2) + Math.pow(deltaH / (1 + 0.015 * c1), 2.0)));
+	}
+
+	private float[] fromXyz(float[] xyz) {
+		return fromXyz(xyz[0], xyz[1], xyz[2]);
+	}
+
+	/**
+	 * 从xyz换算<br>
+	 * L=116f(y)-16<br>
+	 * a=500[f(x/0.982)-f(y)]<br>
+	 * b=200[f(y)-f(z/1.183 )]<br>
+	 * 其中： f(x)=7.787x+0.138, x<0.008856; f(x)=(x)1/3,x>0.008856
+	 *
+	 * @param x X
+	 * @param y Y
+	 * @param z Z
+	 * @return Lab
+	 */
+	private static float[] fromXyz(float x, float y, float z) {
+		final double l = (f(y) - 16.0) * 116.0;
+		final double a = (f(x) - f(y)) * 500.0;
+		final double b = (f(y) - f(z)) * 200.0;
+		return new float[]{(float) l, (float) a, (float) b};
+	}
+
+	private static double f(double t) {
+		return (t > (216.0 / 24389.0)) ? Math.cbrt(t) : (1.0 / 3.0) * Math.pow(29.0 / 6.0, 2) * t + (4.0 / 29.0);
+	}
+}