/*

 * 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

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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);

    }

}