Convert range of colors to a traditional Minecraft Chat Color Pre 1.16

ColorTest.java

package io.mystiflow;

import com.google.common.collect.ImmutableMap;
import com.google.common.collect.Sets;
import java.awt.*;
import net.md_5.bungee.api.ChatColor;
import org.junit.Assert;
import org.junit.Test;

import java.util.Map;
import java.util.Set;

public class ColorTest {

    // List of ChatColor's to not process
    private static final Set<ChatColor> STYLE_COLORS;

    // Mapping of Spigot ChatColor to appropriate Java Color
    private static final Map<ChatColor, Color> COLOR_MAPPINGS;

    static {
        STYLE_COLORS = Sets.immutableEnumSet(
                ChatColor.BOLD,
                ChatColor.UNDERLINE,
                ChatColor.STRIKETHROUGH,
                ChatColor.RESET,
                ChatColor.ITALIC,
                ChatColor.MAGIC
        );

        // https://minecraft.gamepedia.com/Formatting_codes#Color_codes
        COLOR_MAPPINGS = ImmutableMap.<ChatColor, Color>builder()
                .put(ChatColor.BLACK, new Color(0, 0, 0))
                .put(ChatColor.DARK_BLUE, new Color(0, 0, 170))
                .put(ChatColor.DARK_GREEN, new Color(0, 170, 0))
                .put(ChatColor.DARK_AQUA, new Color(0, 170, 170))
                .put(ChatColor.DARK_RED, new Color(170, 0, 0))
                .put(ChatColor.DARK_PURPLE, new Color(170, 0, 170))
                .put(ChatColor.GOLD, new Color(255, 170, 0))
                .put(ChatColor.GRAY, new Color(170, 170, 170))
                .put(ChatColor.DARK_GRAY, new Color(85, 85, 85))
                .put(ChatColor.BLUE, new Color(85, 85, 255))
                .put(ChatColor.GREEN, new Color(85, 255, 85))
                .put(ChatColor.AQUA, new Color(85, 255, 255))
                .put(ChatColor.RED, new Color(255, 85, 85))
                .put(ChatColor.LIGHT_PURPLE, new Color(255, 85, 255))
                .put(ChatColor.YELLOW, new Color(255, 255, 85))
                .put(ChatColor.WHITE, new Color(255, 255, 255))
                .build();
    }

    public static String rgbToHex(int rgb) {
        return Integer.toHexString(rgb).substring(2);
    }

    public static int hexToRgb(String hex) {
        return Integer.valueOf(hex, 16);
    }

    public static int getRgb(int red, int green, int blue) {
        return new Color(red, green, blue).getRGB();
    }

    public static String formattedRgb(Color color) {
        return "(" + color.getRed() + ", " + color.getGreen() + ", " + color.getBlue() + ")";
    }

    @Test
    public void testColorMatching() {
        for (ChatColor chatColor : ChatColor.values()) {
            if (STYLE_COLORS.contains(chatColor)) continue;

            Color color = COLOR_MAPPINGS.get(chatColor);

            Assert.assertEquals(getClosestChatColor(color), chatColor);

            // Test with slightly mutated colors
            Assert.assertEquals(chatColor,
                    getClosestChatColor(new Color(Math.min(255, color.getRed() + 10), color.getGreen(), color.getBlue())));
            Assert.assertNotEquals(chatColor,
                    getClosestChatColor(new Color(color.getRed(), (color.getGreen() < 128) ? 255 : 0, color.getBlue())));
            Assert.assertEquals(chatColor,
                    getClosestChatColor(new Color(color.getRed(), color.getGreen(), Math.max(0, color.getBlue() - 10))));
        }
        
        // General color match testing
        String hex = "9F34BA";
        System.out.println("Closest color for (" + hex + ") = " + getClosestChatColor(new Color(hexToRgb(hex))).getName());
    }

    private static ChatColor getClosestChatColor(Color color) {
        ChatColor closest = null;
        int mark = 0;
        for (Map.Entry<ChatColor, Color> entry : COLOR_MAPPINGS.entrySet()) {
            ChatColor key = entry.getKey();
            Color value = entry.getValue();

            int diff = getDiff(value, color);
            if (closest == null || diff < mark) {
                closest = key;
                mark = diff;
            }
        }
        
        return closest;
    }

    // Algorithm to determine the difference between two colors, source:
    // https://stackoverflow.com/questions/27374550/how-to-compare-color-object-and-get-closest-color-in-an-color
    private static int getDiff(Color color, Color compare) {
        int a = color.getAlpha() - compare.getAlpha(),
                r = color.getRed() - compare.getRed(),
                g = color.getGreen() - compare.getGreen(),
                b = color.getBlue() - compare.getBlue();
        return a * a + r * r + g * g + b * b;
    }
}

Thanks for your effort, i took a part of it and it works perfectly! 🙂

Thanks for the work