colorutil.java.svn-base

来自「开源项目openfire的完整源程序」· SVN-BASE 代码 · 共 233 行

/**
 * $Revision$
 * $Date$
 *
 * Copyright (C) 1999-2005 Jive Software. All rights reserved.
 * This software is the proprietary information of Jive Software. Use is subject to license terms.
 */

package org.jivesoftware.spark.util;

/*
 * This code is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This code 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this program; if not, write to the Free
 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
 * MA  02111-1307, USA.
 */


import java.awt.Color;


/**
 * Common color utilities.
 *
 * @author <a href="mailto:[e-mail]">Jacob Dreyer</a>
 */
public class ColorUtil {
    /**
     * Blend two colors.
     *
     * @param color1 First color to blend.
     * @param color2 Second color to blend.
     * @param ratio  Blend ratio. 0.5 will give even blend, 1.0 will return
     *               color1, 0.0 will return color2 and so on.
     * @return Blended color.
     */
    public static Color blend(Color color1, Color color2, double ratio) {
        float r = (float)ratio;
        float ir = (float)1.0 - r;

        float rgb1[] = new float[3];
        float rgb2[] = new float[3];

        color1.getColorComponents(rgb1);
        color2.getColorComponents(rgb2);

        Color color = new Color(rgb1[0] * r + rgb2[0] * ir,
                rgb1[1] * r + rgb2[1] * ir,
                rgb1[2] * r + rgb2[2] * ir);

        return color;
    }


    /**
     * Make an even blend between two colors.
     *
     * @param color1 First color to blend.
     * @param color2 Second color to blend.
     * @return Blended color.
     */
    public static Color blend(Color color1, Color color2) {
        return ColorUtil.blend(color1, color2, 0.5);
    }


    /**
     * Make a color darker.
     *
     * @param color    Color to make darker.
     * @param fraction Darkness fraction.
     * @return Darker color.
     */
    public static Color darker(Color color, double fraction) {
        int red = (int)Math.round(color.getRed() * (1.0 - fraction));
        int green = (int)Math.round(color.getGreen() * (1.0 - fraction));
        int blue = (int)Math.round(color.getBlue() * (1.0 - fraction));

        if (red < 0) red = 0;
        else if (red > 255) red = 255;
        if (green < 0) green = 0;
        else if (green > 255) green = 255;
        if (blue < 0) blue = 0;
        else if (blue > 255) blue = 255;

        int alpha = color.getAlpha();

        return new Color(red, green, blue, alpha);
    }


    /**
     * Make a color lighter.
     *
     * @param color    Color to make lighter.
     * @param fraction Darkness fraction.
     * @return Lighter color.
     */
    public static Color lighter(Color color, double fraction) {
        int red = (int)Math.round(color.getRed() * (1.0 + fraction));
        int green = (int)Math.round(color.getGreen() * (1.0 + fraction));
        int blue = (int)Math.round(color.getBlue() * (1.0 + fraction));

        if (red < 0) red = 0;
        else if (red > 255) red = 255;
        if (green < 0) green = 0;
        else if (green > 255) green = 255;
        if (blue < 0) blue = 0;
        else if (blue > 255) blue = 255;

        int alpha = color.getAlpha();

        return new Color(red, green, blue, alpha);
    }


    /**
     * Return the hex name of a specified color.
     *
     * @param color Color to get hex name of.
     * @return Hex name of color: "rrggbb".
     */
    public static String getHexName(Color color) {
        int r = color.getRed();
        int g = color.getGreen();
        int b = color.getBlue();

        String rHex = Integer.toString(r, 16);
        String gHex = Integer.toString(g, 16);
        String bHex = Integer.toString(b, 16);

        return (rHex.length() == 2 ? "" + rHex : "0" + rHex) +
                (gHex.length() == 2 ? "" + gHex : "0" + gHex) +
                (bHex.length() == 2 ? "" + bHex : "0" + bHex);
    }


    /**
     * Return the "distance" between two colors. The rgb entries are taken
     * to be coordinates in a 3D space [0.0-1.0], and this method returnes
     * the distance between the coordinates for the first and second color.
     *
     * @param r1, g1, b1  First color.
     * @param r2, g2, b2  Second color.
     * @return Distance bwetween colors.
     */
    public static double colorDistance(double r1, double g1, double b1,
                                       double r2, double g2, double b2) {
        double a = r2 - r1;
        double b = g2 - g1;
        double c = b2 - b1;

        return Math.sqrt(a * a + b * b + c * c);
    }


    /**
     * Return the "distance" between two colors.
     *
     * @param color1 First color [r,g,b].
     * @param color2 Second color [r,g,b].
     * @return Distance bwetween colors.
     */
    public static double colorDistance(double[] color1, double[] color2) {
        return ColorUtil.colorDistance(color1[0], color1[1], color1[2],
                color2[0], color2[1], color2[2]);
    }


    /**
     * Return the "distance" between two colors.
     *
     * @param color1 First color.
     * @param color2 Second color.
     * @return Distance between colors.
     */
    public static double colorDistance(Color color1, Color color2) {
        float rgb1[] = new float[3];
        float rgb2[] = new float[3];

        color1.getColorComponents(rgb1);
        color2.getColorComponents(rgb2);

        return ColorUtil.colorDistance(rgb1[0], rgb1[1], rgb1[2],
                rgb2[0], rgb2[1], rgb2[2]);
    }


    /**
     * Check if a color is more dark than light. Useful if an entity of
     * this color is to be labeled: Use white label on a "dark" color and
     * black label on a "light" color.
     *
     * @param r,g,b Color to check.
     * @return True if this is a "dark" color, false otherwise.
     */
    public static boolean isDark(double r, double g, double b) {
        // Measure distance to white and black respectively
        double dWhite = ColorUtil.colorDistance(r, g, b, 1.0, 1.0, 1.0);
        double dBlack = ColorUtil.colorDistance(r, g, b, 0.0, 0.0, 0.0);

        return dBlack < dWhite;
    }


    /**
     * Check if a color is more dark than light. Useful if an entity of
     * this color is to be labeled: Use white label on a "dark" color and
     * black label on a "light" color.
     *
     * @param color Color to check.
     * @return True if this is a "dark" color, false otherwise.
     */
    public static boolean isDark(Color color) {
        float r = color.getRed() / 255.0f;
        float g = color.getGreen() / 255.0f;
        float b = color.getBlue() / 255.0f;

        return isDark(r, g, b);
    }
}