Java tutorial
/******************************************************************************* * Copyright (c) 2000, 2013 IBM Corporation and others. * * This program and the accompanying materials * are made available under the terms of the Eclipse Public License 2.0 * which accompanies this distribution, and is available at * https://www.eclipse.org/legal/epl-2.0/ * * SPDX-License-Identifier: EPL-2.0 * * Contributors: * IBM Corporation - initial API and implementation *******************************************************************************/ package org.eclipse.swt.graphics; import java.io.*; import org.eclipse.swt.*; /** * Instances of this class are descriptions of colors in * terms of the primary additive color model (red, green and * blue). A color may be described in terms of the relative * intensities of these three primary colors. The brightness * of each color is specified by a value in the range 0 to 255, * where 0 indicates no color (blackness) and 255 indicates * maximum intensity. * <p> * The hashCode() method in this class uses the values of the public * fields to compute the hash value. When storing instances of the * class in hashed collections, do not modify these fields after the * object has been inserted. * </p> * <p> * Application code does <em>not</em> need to explicitly release the * resources managed by each instance when those instances are no longer * required, and thus no <code>dispose()</code> method is provided. * </p> * * @see Color * @see <a href="http://www.eclipse.org/swt/snippets/#color">Color and RGB snippets</a> * @see <a href="http://www.eclipse.org/swt/">Sample code and further information</a> */ public final class RGB implements Serializable { /** * the red component of the RGB */ public int red; /** * the green component of the RGB */ public int green; /** * the blue component of the RGB */ public int blue; static final long serialVersionUID = 3258415023461249074L; /** * Constructs an instance of this class with the given * red, green and blue values. * * @param red the red component of the new instance * @param green the green component of the new instance * @param blue the blue component of the new instance * * @exception IllegalArgumentException <ul> * <li>ERROR_INVALID_ARGUMENT - if the red, green or blue argument is not between 0 and 255</li> * </ul> */ public RGB(int red, int green, int blue) { if ((red > 255) || (red < 0) || (green > 255) || (green < 0) || (blue > 255) || (blue < 0)) SWT.error(SWT.ERROR_INVALID_ARGUMENT); this.red = red; this.green = green; this.blue = blue; } /** * Constructs an instance of this class with the given * hue, saturation, and brightness. * * @param hue the hue value for the HSB color (from 0 to 360) * @param saturation the saturation value for the HSB color (from 0 to 1) * @param brightness the brightness value for the HSB color (from 0 to 1) * * @exception IllegalArgumentException <ul> * <li>ERROR_INVALID_ARGUMENT - if the hue is not between 0 and 360 or * the saturation or brightness is not between 0 and 1</li> * </ul> * * @since 3.2 */ public RGB(float hue, float saturation, float brightness) { if (hue < 0 || hue > 360 || saturation < 0 || saturation > 1 || brightness < 0 || brightness > 1) { SWT.error(SWT.ERROR_INVALID_ARGUMENT); } float r, g, b; if (saturation == 0) { r = g = b = brightness; } else { if (hue == 360) hue = 0; hue /= 60; int i = (int) hue; float f = hue - i; float p = brightness * (1 - saturation); float q = brightness * (1 - saturation * f); float t = brightness * (1 - saturation * (1 - f)); switch (i) { case 0: r = brightness; g = t; b = p; break; case 1: r = q; g = brightness; b = p; break; case 2: r = p; g = brightness; b = t; break; case 3: r = p; g = q; b = brightness; break; case 4: r = t; g = p; b = brightness; break; case 5: default: r = brightness; g = p; b = q; break; } } red = (int) (r * 255 + 0.5); green = (int) (g * 255 + 0.5); blue = (int) (b * 255 + 0.5); } /** * Returns the hue, saturation, and brightness of the color. * * @return color space values in float format:<ul> * <li>hue (from 0 to 360)</li> * <li>saturation (from 0 to 1)</li> * <li>brightness (from 0 to 1)</li> * </ul> * @see #RGB(float, float, float) * * @since 3.2 */ public float[] getHSB() { float r = red / 255f; float g = green / 255f; float b = blue / 255f; float max = Math.max(Math.max(r, g), b); float min = Math.min(Math.min(r, g), b); float delta = max - min; float hue = 0; float brightness = max; float saturation = max == 0 ? 0 : (max - min) / max; if (delta != 0) { if (r == max) { hue = (g - b) / delta; } else { if (g == max) { hue = 2 + (b - r) / delta; } else { hue = 4 + (r - g) / delta; } } hue *= 60; if (hue < 0) hue += 360; } return new float[] { hue, saturation, brightness }; } /** * Compares the argument to the receiver, and returns true * if they represent the <em>same</em> object using a class * specific comparison. * * @param object the object to compare with this object * @return <code>true</code> if the object is the same as this object and <code>false</code> otherwise * * @see #hashCode() */ @Override public boolean equals(Object object) { if (object == this) return true; if (!(object instanceof RGB)) return false; RGB rgb = (RGB) object; return (rgb.red == this.red) && (rgb.green == this.green) && (rgb.blue == this.blue); } /** * Returns an integer hash code for the receiver. Any two * objects that return <code>true</code> when passed to * <code>equals</code> must return the same value for this * method. * * @return the receiver's hash * * @see #equals(Object) */ @Override public int hashCode() { return (blue << 16) | (green << 8) | red; } /** * Returns a string containing a concise, human-readable * description of the receiver. * * @return a string representation of the <code>RGB</code> */ @Override public String toString() { return "RGB {" + red + ", " + green + ", " + blue + "}"; //$NON-NLS-1$//$NON-NLS-2$ //$NON-NLS-3$ //$NON-NLS-4$ } }