ColourMap.java

/*
 * This file is part of HoloAPI.
 *
 * HoloAPI is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * HoloAPI is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with HoloAPI.  If not, see <http://www.gnu.org/licenses/>.
 */

package com.dsh105.holoapi.image;

import org.bukkit.ChatColor;

import java.awt.*;

public class ColourMap {
    protected static final Color[] colors = {
            new Color(0, 0, 0),
            new Color(0, 0, 170),
            new Color(0, 170, 0),
            new Color(0, 170, 170),
            new Color(170, 0, 0),
            new Color(170, 0, 170),
            new Color(255, 170, 0),
            new Color(170, 170, 170),
            new Color(85, 85, 85),
            new Color(85, 85, 255),
            new Color(85, 255, 85),
            new Color(85, 255, 255),
            new Color(255, 85, 85),
            new Color(255, 85, 255),
            new Color(255, 255, 85),
            new Color(255, 255, 255),
    };

    protected static ChatColor getClosest(Color color) {
        if (color.getAlpha() < 128) return null;

        int index = 0;
        double best = -1;

        for (int i = 0; i < ColourMap.colors.length; i++) {
            if (areIdentical(ColourMap.colors[i], color)) {
                return ChatColor.values()[i];
            }
        }

        for (int i = 0; i < ColourMap.colors.length; i++) {
            double distance = getDistance(color, ColourMap.colors[i]);
            if (distance < best || best == -1) {
                best = distance;
                index = i;
            }
        }

        // Minecraft has 15 colors
        return ChatColor.values()[index];
    }

    private static boolean areIdentical(Color c1, Color c2) {
        return Math.abs(c1.getRed() - c2.getRed()) <= 5 &&
                Math.abs(c1.getGreen() - c2.getGreen()) <= 5 &&
                Math.abs(c1.getBlue() - c2.getBlue()) <= 5;

    }

    private static double getDistance(Color c1, Color c2) {
        double rmean = (c1.getRed() + c2.getRed()) / 2.0;
        double r = c1.getRed() - c2.getRed();
        double g = c1.getGreen() - c2.getGreen();
        int b = c1.getBlue() - c2.getBlue();
        double weightR = 2 + rmean / 256.0;
        double weightG = 4.0;
        double weightB = 2 + (255 - rmean) / 256.0;
        return weightR * r * r + weightG * g * g + weightB * b * b;
    }
}