Color Utilities: common color operations
/*
* $Id: ColorUtilities.java,v 1.1 2006/12/15 13:53:13 gfx Exp $
*
* Dual-licensed under LGPL (Sun and Romain Guy) and BSD (Romain Guy).
*
* Copyright 2006 Sun Microsystems, Inc., 4150 Network Circle,
* Santa Clara, California 95054, U.S.A. All rights reserved.
*
* Copyright (c) 2006 Romain Guy <romain.guy@mac.com>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/**
* <p><code>ColorUtilities</code> contains a set of tools to perform
* common color operations easily.</p>
*
* @author Romain Guy <romain.guy@mac.com>
*/
class ColorUtilities {
private ColorUtilities() {
}
/**
* <p>Returns the HSL (Hue/Saturation/Luminance) equivalent of a given
* RGB color. All three HSL components are between 0.0 and 1.0.</p>
*
* @param color the RGB color to convert
* @return a new array of 3 floats corresponding to the HSL components
*/
public static float[] RGBtoHSL(Color color) {
return RGBtoHSL(color.getRed(), color.getGreen(), color.getBlue(), null);
}
/**
* <p>Returns the HSL (Hue/Saturation/Luminance) equivalent of a given
* RGB color. All three HSL components are between 0.0 and 1.0.</p>
*
* @param color the RGB color to convert
* @param hsl a pre-allocated array of floats; can be null
* @return <code>hsl</code> if non-null, a new array of 3 floats otherwise
* @throws IllegalArgumentException if <code>hsl</code> has a length lower
* than 3
*/
public static float[] RGBtoHSL(Color color, float[] hsl) {
return RGBtoHSL(color.getRed(), color.getGreen(), color.getBlue(), hsl);
}
/**
* <p>Returns the HSL (Hue/Saturation/Luminance) equivalent of a given
* RGB color. All three HSL components are between 0.0 and 1.0.</p>
*
* @param r the red component, between 0 and 255
* @param g the green component, between 0 and 255
* @param b the blue component, between 0 and 255
* @return a new array of 3 floats corresponding to the HSL components
*/
public static float[] RGBtoHSL(int r, int g, int b) {
return RGBtoHSL(r, g, b, null);
}
/**
* <p>Returns the HSL (Hue/Saturation/Luminance) equivalent of a given
* RGB color. All three HSL components are floats between 0.0 and 1.0.</p>
*
* @param r the red component, between 0 and 255
* @param g the green component, between 0 and 255
* @param b the blue component, between 0 and 255
* @param hsl a pre-allocated array of floats; can be null
* @return <code>hsl</code> if non-null, a new array of 3 floats otherwise
* @throws IllegalArgumentException if <code>hsl</code> has a length lower
* than 3
*/
public static float[] RGBtoHSL(int r, int g, int b, float[] hsl) {
if (hsl == null) {
hsl = new float[3];
} else if (hsl.length < 3) {
throw new IllegalArgumentException("hsl array must have a length of" +
" at least 3");
}
if (r < 0) r = 0;
else if (r > 255) r = 255;
if (g < 0) g = 0;
else if (g > 255) g = 255;
if (b < 0) b = 0;
else if (b > 255) b = 255;
float var_R = (r / 255f);
float var_G = (g / 255f);
float var_B = (b / 255f);
float var_Min;
float var_Max;
float del_Max;
if (var_R > var_G) {
var_Min = var_G;
var_Max = var_R;
} else {
var_Min = var_R;
var_Max = var_G;
}
if (var_B > var_Max) {
var_Max = var_B;
}
if (var_B < var_Min) {
var_Min = var_B;
}
del_Max = var_Max - var_Min;
float H, S, L;
L = (var_Max + var_Min) / 2f;
if (del_Max - 0.01f <= 0.0f) {
H = 0;
S = 0;
} else {
if (L < 0.5f) {
S = del_Max / (var_Max + var_Min);
} else {
S = del_Max / (2 - var_Max - var_Min);
}
float del_R = (((var_Max - var_R) / 6f) + (del_Max / 2f)) / del_Max;
float del_G = (((var_Max - var_G) / 6f) + (del_Max / 2f)) / del_Max;
float del_B = (((var_Max - var_B) / 6f) + (del_Max / 2f)) / del_Max;
if (var_R == var_Max) {
H = del_B - del_G;
} else if (var_G == var_Max) {
H = (1 / 3f) + del_R - del_B;
} else {
H = (2 / 3f) + del_G - del_R;
}
if (H < 0) {
H += 1;
}
if (H > 1) {
H -= 1;
}
}
hsl[0] = H;
hsl[1] = S;
hsl[2] = L;
return hsl;
}
/**
* <p>Returns the RGB equivalent of a given HSL (Hue/Saturation/Luminance)
* color.</p>
*
* @param h the hue component, between 0.0 and 1.0
* @param s the saturation component, between 0.0 and 1.0
* @param l the luminance component, between 0.0 and 1.0
* @return a new <code>Color</code> object equivalent to the HSL components
*/
public static Color HSLtoRGB(float h, float s, float l) {
int[] rgb = HSLtoRGB(h, s, l, null);
return new Color(rgb[0], rgb[1], rgb[2]);
}
/**
* <p>Returns the RGB equivalent of a given HSL (Hue/Saturation/Luminance)
* color. All three RGB components are integers between 0 and 255.</p>
*
* @param h the hue component, between 0.0 and 1.0
* @param s the saturation component, between 0.0 and 1.0
* @param l the luminance component, between 0.0 and 1.0
* @param rgb a pre-allocated array of ints; can be null
* @return <code>rgb</code> if non-null, a new array of 3 ints otherwise
* @throws IllegalArgumentException if <code>rgb</code> has a length lower
* than 3
*/
public static int[] HSLtoRGB(float h, float s, float l, int[] rgb) {
if (rgb == null) {
rgb = new int[3];
} else if (rgb.length < 3) {
throw new IllegalArgumentException("rgb array must have a length of" +
" at least 3");
}
if (h < 0) h = 0.0f;
else if (h > 1.0f) h = 1.0f;
if (s < 0) s = 0.0f;
else if (s > 1.0f) s = 1.0f;
if (l < 0) l = 0.0f;
else if (l > 1.0f) l = 1.0f;
int R, G, B;
if (s - 0.01f <= 0.0f) {
R = (int) (l * 255.0f);
G = (int) (l * 255.0f);
B = (int) (l * 255.0f);
} else {
float var_1, var_2;
if (l < 0.5f) {
var_2 = l * (1 + s);
} else {
var_2 = (l + s) - (s * l);
}
var_1 = 2 * l - var_2;
R = (int) (255.0f * hue2RGB(var_1, var_2, h + (1.0f / 3.0f)));
G = (int) (255.0f * hue2RGB(var_1, var_2, h));
B = (int) (255.0f * hue2RGB(var_1, var_2, h - (1.0f / 3.0f)));
}
rgb[0] = R;
rgb[1] = G;
rgb[2] = B;
return rgb;
}
private static float hue2RGB(float v1, float v2, float vH) {
if (vH < 0.0f) {
vH += 1.0f;
}
if (vH > 1.0f) {
vH -= 1.0f;
}
if ((6.0f * vH) < 1.0f) {
return (v1 + (v2 - v1) * 6.0f * vH);
}
if ((2.0f * vH) < 1.0f) {
return (v2);
}
if ((3.0f * vH) < 2.0f) {
return (v1 + (v2 - v1) * ((2.0f / 3.0f) - vH) * 6.0f);
}
return (v1);
}
}
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