ColorHelper.java Source code

Introduction

Here is the source code for ColorHelper.java

Source

//package org.boticelli.util;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

public class ColorHelper {
    private final static int H_STEPS = 12;

    private final static int S_STEPS = 3;

    private final static float S_STEP_VALUE = 0.05f;

    private final static float S_MIN_VALUE = 0.15f;

    private final static List<String> staticColors;

    static {
        List<String> colors = new ArrayList<String>();
        float v = 1.0f;
        for (int j = 0; j < H_STEPS; j++) {
            float h = j * 6.0f / H_STEPS;
            for (int i = 0; i < S_STEPS; i++) {
                float s = S_MIN_VALUE + (i * S_STEP_VALUE);

                float[] rgb = HSVtoRGB(h, s, v);

                int r = (int) (rgb[0] * 255.0f);
                int g = (int) (rgb[1] * 255.0f);
                int b = (int) (rgb[2] * 255.0f);

                String col = Integer.toHexString((r << 16) + (g << 8) + b);
                col = "000000".substring(col.length()) + col;
                colors.add("#" + col);
            }
        }

        staticColors = Collections.unmodifiableList(colors);
    }

    public int getColorIndexFor(String ident) {
        return Math.abs(ident.hashCode()) % staticColors.size();
    }

    public static float[] HSVtoRGB(float h, float s, float v) {
        // H is given on [0->6] or -1. S and V are given on [0->1].
        // RGB are each returned on [0->1].
        float m, n, f;
        int i;

        float[] hsv = new float[3];
        float[] rgb = new float[3];

        hsv[0] = h;
        hsv[1] = s;
        hsv[2] = v;

        if (hsv[0] == -1) {
            rgb[0] = rgb[1] = rgb[2] = hsv[2];
            return rgb;
        }
        i = (int) (Math.floor(hsv[0]));
        f = hsv[0] - i;
        if (i % 2 == 0) {
            f = 1 - f; // if i is even
        }
        m = hsv[2] * (1 - hsv[1]);
        n = hsv[2] * (1 - hsv[1] * f);
        switch (i) {
        case 6:
        case 0:
            rgb[0] = hsv[2];
            rgb[1] = n;
            rgb[2] = m;
            break;
        case 1:
            rgb[0] = n;
            rgb[1] = hsv[2];
            rgb[2] = m;
            break;
        case 2:
            rgb[0] = m;
            rgb[1] = hsv[2];
            rgb[2] = n;
            break;
        case 3:
            rgb[0] = m;
            rgb[1] = n;
            rgb[2] = hsv[2];
            break;
        case 4:
            rgb[0] = n;
            rgb[1] = m;
            rgb[2] = hsv[2];
            break;
        case 5:
            rgb[0] = hsv[2];
            rgb[1] = m;
            rgb[2] = n;
            break;
        }

        return rgb;

    }

    public static List<String> getColors() {
        return staticColors;
    }
}