!1252 增加图形验证码文字颜色与背景颜色色差设置

Merge pull request !1252 from czc/v5-dev

hutool-captcha/src/test/java/cn/hutool/captcha/CaptchaUtilTest.java

@@ -1,8 +1,18 @@
 package cn.hutool.captcha;
 
+import cn.hutool.captcha.generator.CodeGenerator;
+import cn.hutool.captcha.generator.MathGenerator;
+import cn.hutool.core.img.GraphicsUtil;
+import cn.hutool.core.img.ImgUtil;
+import cn.hutool.core.util.ObjectUtil;
+import cn.hutool.core.util.RandomUtil;
 import org.junit.Ignore;
 import org.junit.Test;
 
+import java.awt.*;
+import java.awt.image.BufferedImage;
+import java.util.concurrent.ThreadLocalRandom;
+
 public class CaptchaUtilTest {
 
 	@Test
@@ -12,4 +22,69 @@ public class CaptchaUtilTest {
 			CaptchaUtil.createShearCaptcha(320, 240);
 		}
 	}
+
+	@Test
+	@Ignore
+	public void drawStringColourfulTest() {
+		for(int i = 0; i < 10; i++) {
+			AbstractCaptcha lineCaptcha = new TestLineCaptcha(200, 100, 5, 10);
+			lineCaptcha.write("d:/captcha/line"+i+".png");
+		}
+	}
+
+	static class TestLineCaptcha extends AbstractCaptcha{
+
+		public TestLineCaptcha(int width, int height, int codeCount, int interfereCount) {
+			super(width, height, codeCount, interfereCount);
+		}
+
+		@Override
+		protected Image createImage(String code) {
+			// 图像buffer
+			final BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
+			final Graphics2D g = GraphicsUtil.createGraphics(image, ObjectUtil.defaultIfNull(this.background, Color.WHITE));
+
+			// 干扰线
+			drawInterfere(g);
+
+			// 字符串
+			drawString(g, code);
+
+			return image;
+		}
+
+		// ----------------------------------------------------------------------------------------------------- Private method start
+		/**
+		 * 绘制字符串
+		 *
+		 * @param g {@link Graphics}画笔
+		 * @param code 验证码
+		 */
+		private void drawString(Graphics2D g, String code) {
+			// 指定透明度
+			if (null != this.textAlpha) {
+				g.setComposite(this.textAlpha);
+			}
+			GraphicsUtil.drawStringColourful(g, code, this.font, this.width, this.height,Color.WHITE,200);
+		}
+
+		/**
+		 * 绘制干扰线
+		 *
+		 * @param g {@link Graphics2D}画笔
+		 */
+		private void drawInterfere(Graphics2D g) {
+			final ThreadLocalRandom random = RandomUtil.getRandom();
+			// 干扰线
+			for (int i = 0; i < this.interfereCount; i++) {
+				int xs = random.nextInt(width);
+				int ys = random.nextInt(height);
+				int xe = xs + random.nextInt(width / 3);
+				int ye = ys + random.nextInt(height / 3);
+				g.setColor(ImgUtil.randomColor(random));
+				g.drawLine(xs, ys, xe, ye);
+			}
+		}
+		// ----------------------------------------------------------------------------------------------------- Private method start
+	}
 }

hutool-core/src/main/java/cn/hutool/core/img/ColorUtil.java

@@ -179,6 +179,39 @@ public class ColorUtil {
 		return randomColor(null);
 	}
 
+	/**
+	 * 生成随机颜色，与指定颜色有一定的区分度
+	 *
+	 * @param compareColor 比较颜色
+	 * @param minDistance 最小色差，按三维坐标计算的距离值
+	 * @return 随机颜色
+	 * @since 5.8.30
+	 */
+	public static Color randomColor(Color compareColor,int minDistance) {
+		Color color = randomColor(null);
+		while (computeColorDistance(compareColor,color) < minDistance) {
+			color = randomColor(null);
+		}
+		return color;
+	}
+
+	/**
+	 * 计算两个颜色之间的色差，按三维坐标距离计算
+	 *
+	 * @param color1 颜色1
+	 * @param color2 颜色2
+	 * @return 色差，按三维坐标距离值
+	 * @since 5.8.30
+	 */
+	public static int computeColorDistance(Color color1, Color color2) {
+		if (null == color1 || null == color2) {
+			return 0;
+		}
+		return (int) Math.sqrt(Math.pow(color1.getRed() - color2.getRed(), 2)
+				+ Math.pow(color1.getGreen() - color2.getGreen(), 2)
+				+ Math.pow(color1.getBlue() - color2.getBlue(), 2));
+	}
+
 	/**
 	 * 生成随机颜色
 	 *

hutool-core/src/main/java/cn/hutool/core/img/GraphicsUtil.java

@@ -81,7 +81,24 @@ public class GraphicsUtil {
 	 * @since 4.5.10
 	 */
 	public static Graphics drawStringColourful(Graphics g, String str, Font font, int width, int height) {
-		return drawString(g, str, font, null, width, height);
+		return drawString(g, str, font, null, width, height, null, 0);
+	}
+
+	/**
+	 * 绘制字符串，使用随机颜色，默认抗锯齿
+	 *
+	 * @param g      {@link Graphics}画笔
+	 * @param str    字符串
+	 * @param font   字体
+	 * @param width  字符串总宽度
+	 * @param height 字符串背景高度
+	 * @param compareColor 用于比对的颜色
+	 * @param minColorDistance 随机生成的颜色与对比颜色的最小色差，小于此值则重新生成颜色
+	 * @return 画笔对象
+	 * @since 4.5.10
+	 */
+	public static Graphics drawStringColourful(Graphics g, String str, Font font, int width, int height, Color compareColor, int minColorDistance) {
+		return drawString(g, str, font, null, width, height, compareColor, minColorDistance);
 	}
 
 	/**
@@ -93,10 +110,12 @@ public class GraphicsUtil {
 	 * @param color  字体颜色，{@code null} 表示使用随机颜色（每个字符单独随机）
 	 * @param width  字符串背景的宽度
 	 * @param height 字符串背景的高度
+	 * @param compareColor 用于比对的颜色
+	 * @param minColorDistance 随机生成的颜色与对比颜色的最小色差，小于此值则重新生成颜色
 	 * @return 画笔对象
 	 * @since 4.5.10
 	 */
-	public static Graphics drawString(Graphics g, String str, Font font, Color color, int width, int height) {
+	public static Graphics drawString(Graphics g, String str, Font font, Color color, int width, int height, Color compareColor, int minColorDistance) {
 		// 抗锯齿
 		if (g instanceof Graphics2D) {
 			((Graphics2D) g).setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
@@ -115,7 +134,11 @@ public class GraphicsUtil {
 		for (int i = 0; i < len; i++) {
 			if (null == color) {
 				// 产生随机的颜色值，让输出的每个字符的颜色值都将不同。
-				g.setColor(ImgUtil.randomColor());
+				if (null != compareColor && minColorDistance > 0) {
+					g.setColor(ImgUtil.randomColor(compareColor,minColorDistance));
+				}else {
+					g.setColor(ImgUtil.randomColor());
+				}
 			}
 			g.drawString(String.valueOf(str.charAt(i)), i * charWidth, midY);
 		}
@@ -181,8 +204,8 @@ public class GraphicsUtil {
 	/**
 	 * 绘制图片
 	 *
-	 * @param g         画笔
+	 * @param g     画笔
-	 * @param img       要绘制的图片
+	 * @param img   要绘制的图片
 	 * @param point 绘制的位置，基于左上角
 	 * @return 画笔对象
 	 */
@@ -207,11 +230,11 @@ public class GraphicsUtil {
 	/**
 	 * 设置画笔透明度
 	 *
-	 * @param g 画笔
+	 * @param g     画笔
 	 * @param alpha 透明度：alpha 必须是范围 [0.0, 1.0] 之内（包含边界值）的一个浮点数字
 	 * @return 画笔
 	 */
-	public static Graphics2D setAlpha(Graphics2D g, float alpha){
+	public static Graphics2D setAlpha(Graphics2D g, float alpha) {
 		g.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_ATOP, alpha));
 		return g;
 	}

hutool-core/src/main/java/cn/hutool/core/img/ImgUtil.java

@@ -2225,6 +2225,18 @@ public class ImgUtil {
 		return ColorUtil.randomColor();
 	}
 
+	/**
+	 * 生成随机颜色，与指定颜色有一定的区分度
+	 *
+	 * @param compareColor 比较颜色
+	 * @param minDistance 最小色差，按三维坐标计算的距离值
+	 * @return 与指定颜色有一定的区分度的随机颜色
+	 * @since 5.8.30
+	 */
+	public static Color randomColor(Color compareColor,int minDistance) {
+		return ColorUtil.randomColor(compareColor,minDistance);
+	}
+
 	/**
 	 * 生成随机颜色
 	 *