/* * Copyright (c) 1997, 2010, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation.  Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * 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 General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package java.awt; import java.awt.geom.Point2D;import java.awt.geom.Rectangle2D;import java.awt.geom.AffineTransform;import java.awt.image.ColorModel;import java.beans.ConstructorProperties; /** * The <code>GradientPaint</code> class provides a way to fill * a {@link Shape} with a linear color gradient pattern. * If {@link Point} P1 with {@link Color} C1 and <code>Point</code> P2 with * <code>Color</code> C2 are specified in user space, the * <code>Color</code> on the P1, P2 connecting line is proportionally * changed from C1 to C2.  Any point P not on the extended P1, P2 * connecting line has the color of the point P' that is the perpendicular * projection of P on the extended P1, P2 connecting line. * Points on the extended line outside of the P1, P2 segment can be colored * in one of two ways. * <ul> * <li> * If the gradient is cyclic then the points on the extended P1, P2 * connecting line cycle back and forth between the colors C1 and C2. * <li> * If the gradient is acyclic then points on the P1 side of the segment * have the constant <code>Color</code> C1 while points on the P2 side * have the constant <code>Color</code> C2. * </ul> * * @see Paint * @see Graphics2D#setPaint * @version 10 Feb 1997 */ public class GradientPaint implements Paint {    Point2D.Float p1;    Point2D.Float p2;    Color color1;    Color color2;    boolean cyclic;     /**     * Constructs a simple acyclic <code>GradientPaint</code> object.     * @param x1 x coordinate of the first specified     * <code>Point</code> in user space     * @param y1 y coordinate of the first specified     * <code>Point</code> in user space     * @param color1 <code>Color</code> at the first specified     * <code>Point</code>     * @param x2 x coordinate of the second specified     * <code>Point</code> in user space     * @param y2 y coordinate of the second specified     * <code>Point</code> in user space     * @param color2 <code>Color</code> at the second specified     * <code>Point</code>     * @throws NullPointerException if either one of colors is null     */    public GradientPaint(float x1,                         float y1,                         Color color1,                         float x2,                         float y2,                         Color color2) {        if ((color1 == null) || (color2 == null)) {            throw new NullPointerException("Colors cannot be null");        }         p1 = new Point2D.Float(x1, y1);        p2 = new Point2D.Float(x2, y2);        this.color1 = color1;        this.color2 = color2;    }     /**     * Constructs a simple acyclic <code>GradientPaint</code> object.     * @param pt1 the first specified <code>Point</code> in user space     * @param color1 <code>Color</code> at the first specified     * <code>Point</code>     * @param pt2 the second specified <code>Point</code> in user space     * @param color2 <code>Color</code> at the second specified     * <code>Point</code>     * @throws NullPointerException if either one of colors or points     * is null     */    public GradientPaint(Point2D pt1,                         Color color1,                         Point2D pt2,                         Color color2) {        if ((color1 == null) || (color2 == null) ||            (pt1 == null) || (pt2 == null)) {            throw new NullPointerException("Colors and points should be non-null");        }         p1 = new Point2D.Float((float)pt1.getX(), (float)pt1.getY());        p2 = new Point2D.Float((float)pt2.getX(), (float)pt2.getY());        this.color1 = color1;        this.color2 = color2;    }     /**     * Constructs either a cyclic or acyclic <code>GradientPaint</code>     * object depending on the <code>boolean</code> parameter.     * @param x1 x coordinate of the first specified     * <code>Point</code> in user space     * @param y1 y coordinate of the first specified     * <code>Point</code> in user space     * @param color1 <code>Color</code> at the first specified     * <code>Point</code>     * @param x2 x coordinate of the second specified     * <code>Point</code> in user space     * @param y2 y coordinate of the second specified     * <code>Point</code> in user space     * @param color2 <code>Color</code> at the second specified     * <code>Point</code>     * @param cyclic <code>true</code> if the gradient pattern should cycle     * repeatedly between the two colors; <code>false</code> otherwise     */    public GradientPaint(float x1,                         float y1,                         Color color1,                         float x2,                         float y2,                         Color color2,                         boolean cyclic) {        this (x1, y1, color1, x2, y2, color2);        this.cyclic = cyclic;    }     /**     * Constructs either a cyclic or acyclic <code>GradientPaint</code>     * object depending on the <code>boolean</code> parameter.     * @param pt1 the first specified <code>Point</code>     * in user space     * @param color1 <code>Color</code> at the first specified     * <code>Point</code>     * @param pt2 the second specified <code>Point</code>     * in user space     * @param color2 <code>Color</code> at the second specified     * <code>Point</code>     * @param cyclic <code>true</code> if the gradient pattern should cycle     * repeatedly between the two colors; <code>false</code> otherwise     * @throws NullPointerException if either one of colors or points     * is null     */    @ConstructorProperties({ "point1", "color1", "point2", "color2", "cyclic" })    public GradientPaint(Point2D pt1,                         Color color1,                         Point2D pt2,                         Color color2,                         boolean cyclic) {        this (pt1, color1, pt2, color2);        this.cyclic = cyclic;    }     /**     * Returns a copy of the point P1 that anchors the first color.     * @return a {@link Point2D} object that is a copy of the point     * that anchors the first color of this     * <code>GradientPaint</code>.     */    public Point2D getPoint1() {        return new Point2D.Float(p1.x, p1.y);    }     /**     * Returns the color C1 anchored by the point P1.     * @return a <code>Color</code> object that is the color     * anchored by P1.     */    public Color getColor1() {        return color1;    }     /**     * Returns a copy of the point P2 which anchors the second color.     * @return a {@link Point2D} object that is a copy of the point     * that anchors the second color of this     * <code>GradientPaint</code>.     */    public Point2D getPoint2() {        return new Point2D.Float(p2.x, p2.y);    }     /**     * Returns the color C2 anchored by the point P2.     * @return a <code>Color</code> object that is the color     * anchored by P2.     */    public Color getColor2() {        return color2;    }     /**     * Returns <code>true</code> if the gradient cycles repeatedly     * between the two colors C1 and C2.     * @return <code>true</code> if the gradient cycles repeatedly     * between the two colors; <code>false</code> otherwise.     */    public boolean isCyclic() {        return cyclic;    }     /**     * Creates and returns a {@link PaintContext} used to     * generate a linear color gradient pattern.     * See the {@link Paint#createContext specification} of the     * method in the {@link Paint} interface for information     * on null parameter handling.     *     * @param cm the preferred {@link ColorModel} which represents the most convenient     *           format for the caller to receive the pixel data, or {@code null}     *           if there is no preference.     * @param deviceBounds the device space bounding box     *                     of the graphics primitive being rendered.     * @param userBounds the user space bounding box     *                   of the graphics primitive being rendered.     * @param xform the {@link AffineTransform} from user     *              space into device space.     * @param hints the set of hints that the context object can use to     *              choose between rendering alternatives.     * @return the {@code PaintContext} for     *         generating color patterns.     * @see Paint     * @see PaintContext     * @see ColorModel     * @see Rectangle     * @see Rectangle2D     * @see AffineTransform     * @see RenderingHints     */    public PaintContext createContext(ColorModel cm,                                      Rectangle deviceBounds,                                      Rectangle2D userBounds,                                      AffineTransform xform,                                      RenderingHints hints) {         return new GradientPaintContext(cm, p1, p2, xform,                                        color1, color2, cyclic);    }     /**     * Returns the transparency mode for this <code>GradientPaint</code>.     * @return an integer value representing this <code>GradientPaint</code>     * object's transparency mode.     * @see Transparency     */    public int getTransparency() {        int a1 = color1.getAlpha();        int a2 = color2.getAlpha();        return (((a1 & a2) == 0xff) ? OPAQUE : TRANSLUCENT);    } }