/*

 * CDDL HEADER START

 *

 * The contents of this file are subject to the terms of the

 * Common Development and Distribution License (the "License").

 * You may not use this file except in compliance with the License.

 *

 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE

 * or http://www.opensolaris.org/os/licensing.

 * See the License for the specific language governing permissions

 * and limitations under the License.

 *

 * When distributing Covered Code, include this CDDL HEADER in each

 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.

 * If applicable, add the following below this CDDL HEADER, with the

 * fields enclosed by brackets "[]" replaced with your own identifying

 * information: Portions Copyright [yyyy] [name of copyright owner]

 *

 * CDDL HEADER END

 */

/*

 * Copyright (c) 2009, 2012, Oracle and/or its affiliates. All rights reserved.

 */

package com.oracle.solaris.vp.util.swing;

import java.awt.*;

import javax.swing.*;

public class ColorUtil {

    //

    // Static data

    //

    /**

     * According to the java.awt.Component API, {@code null} should cause the

     * background of a {@code Component} to be transparent.  But buttons and

     * other components of some L∓Fs (<cough> metal <cough>)

     * paint their own background in that case.  So a completely transparent

     * color is provided here instead.

     */

    public static Color TRANSPARENT = new Color(0, 0, 0, 0);

    //

    // Static methods

    //

    /**

     * Returns a color identicial to the given color but with a new alpha.

     *

     * @param	    c

     *		    the subject color

     *

     * @param	    alpha

     *		    the alpha setting

     */

    public static Color alpha(Color c, float alpha) {

	float[] rgb = c.getRGBColorComponents(null);

	return new Color(rgb[0], rgb[1], rgb[2], alpha);

    }

    /**

     * Returns a darker version of the given color by the given factor.

     * <p>

     * Compared with {@code Color.darker()}, this method provides finer

     * control over how much to darken the given color.

     *

     * @param	    c

     *		    the subject color

     *

     * @param	    factor

     *		    a number between 0 (no change) and 1 (resulting color will

     *		    be black) inclusive

     *

     * @return	    a darker (closer to black) version of the given color

     *

     * @exception   IllegalArgumentException

     *		    if factor is not betwee 0 and 1 inclusive

     */

    public static Color darker(Color c, float factor) {

	return blend(c, Color.BLACK, factor);

    }

    public static double distance(Color c1, Color c2) {

	float[] rgb1 = c1.getRGBColorComponents(null);

	float[] rgb2 = c2.getRGBColorComponents(null);

	double x = rgb2[0] - rgb1[0];

	double y = rgb2[1] - rgb1[1];

	double z = rgb2[2] - rgb1[2];

	return Math.sqrt(x * x + y * y + z * z);

    }

    /**

     * Blends the given colors by the given factor.

     *

     * @param	    cFrom

     *		    the color to blend with cTo

     *

     * @param	    cTo

     *		    the color to blend with cFrom

     *

     * @param	    factor

     *		    a number between 0 (resulting color will be {@code cFrom})

     *		    and 1 (resulting color will be {@code cTo}) inclusive, with

     *		    .5 indicating an even blend between the two

     *

     * @return	    a blend of the given colors

     *

     * @exception   IllegalArgumentException

     *		    if factor is not betwee 0 and 1 inclusive

     */

    public static Color blend(Color cFrom, Color cTo, float factor) {

	if (factor < 0f || factor > 1f) {

	    throw new IllegalArgumentException(

		"factor not between 0 and 1: " + factor);

	}

	float[] rgbaFrom = cFrom.getRGBComponents(null);

	float[] rgbaTo = cTo.getRGBComponents(null);

	rgbaFrom[0] += (rgbaTo[0] - rgbaFrom[0]) * factor;

	rgbaFrom[1] += (rgbaTo[1] - rgbaFrom[1]) * factor;

	rgbaFrom[2] += (rgbaTo[2] - rgbaFrom[2]) * factor;

	return new Color(rgbaFrom[0], rgbaFrom[1], rgbaFrom[2], rgbaFrom[3]);

    }

    public static Color getRandomColor() {

	return new Color(

	    (int)(Math.random() * 256),

	    (int)(Math.random() * 256),

	    (int)(Math.random() * 256));

    }

    /**

     * Determines whether the given {@code Color} is more dark than light.

     */

    public static boolean isDark(Color c) {

	double whiteDist = distance(c, Color.WHITE);

	double blackDist = distance(c, Color.BLACK);

	return whiteDist > blackDist;

    }

    /**

     * Returns a lighter version of the given color by the given

     * factor.

     * <p>

     * Compared with {@code Color.brighter()}, this method provides finer

     * control over how much to lighten the given color.

     * <p>

     * Note: When {@code factor > 0}, this method differs functionally from

     * {@code Color.brighter()} - repeated invocations of the former for any

     * color will eventually yield white, whereas the latter will just create a

     * brighter version of the same color.  For "pure" colors (zero r, g, or b),

     * repeated invocations of {@code Color.brighter()} will never yield white.

     *

     * @param	    c

     *		    the subject color

     *

     * @param	    factor

     *		    a number between 0 (no change) and 1 (resulting color will

     *		    be white) inclusive

     *

     * @return	    a lighter (closer to white) version of the given color

     *

     * @exception   IllegalArgumentException

     *		    if factor is not betwee 0 and 1 inclusive

     */

    public static Color lighter(Color c, float factor) {

	return blend(c, Color.WHITE, factor);

    }

    public static void main(String args[]) {

	Color color = Color.RED;

	JPanel panel = new JPanel();

	panel.setLayout(new GridLayout(0, 1, 5, 5));

	for (int i = -10; i <= 10; i++) {

	    float factor = (float)i / (float)10;

	    Color lighter = i < 0 ?

		darker(color, -factor) : lighter(color, factor);

	    JLabel l = new JLabel(factor + ": " + lighter.toString());

	    l.setBackground(lighter);

	    l.setForeground(isDark(lighter) ? Color.WHITE : Color.BLACK);

	    l.setOpaque(true);

	    panel.add(l);

	}

	JFrame frame = new JFrame();

	Container c = frame.getContentPane();

	c.setLayout(new BorderLayout());

	c.add(new JScrollPane(panel), BorderLayout.CENTER);

	frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);

	frame.pack();

	frame.setVisible(true);

    }

}