Java 1.2 How-To/JavaHowTo.iso/3rdParty/jbuilder/unsupported/JDK1.2beta3/SOURCE/SRC.ZIP/java/awt/GradientPaint.java

Java Source | 1998-03-20 | 5.3 KB | 163 lines

/*
 * @(#)GradientPaint.java    1.22 98/03/18
 *
 * Copyright 1997, 1998 by Sun Microsystems, Inc.,
 * 901 San Antonio Road, Palo Alto, California, 94303, U.S.A.
 * All rights reserved.
 *
 * This software is the confidential and proprietary information
 * of Sun Microsystems, Inc. ("Confidential Information").  You
 * shall not disclose such Confidential Information and shall use
 * it only in accordance with the terms of the license agreement
 * you entered into with Sun.
 */

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.awt.image.BufferedImage;

/**
 * This class provides a way to fill a shape with a linear color gradient
 * pattern.
 * Given two points in user space, P1 with the color C1 and P2 with the
 * color C2, the color
 * on the P1, P2 connecting line is changed from C1 to C2 proportionally to
 * the distance to P1.
 * 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.
 * If the gradient is cyclic, then the points on the extended P1, P2
 * connecting line cycle back and forth through the colors from C1 to C2
 * and back to C1 again continuously at an even rate.
 * If the gradient is acyclic, then points on the P1 side of the segment
 * have the constant color C1 while points on the P2 side have the contsant
 * color C2.
 *
 * @see Paint
 * @see Graphics2D#setPaint
 * @version 10 Feb 1997
 */

public class GradientPaint implements Paint {
    Point2D p1;
    Point2D p2;
    Color color1;
    Color color2;
    boolean cyclic;

    /**
     * Constructs a simple acyclic GradientPaint object.
     * @param x1,y1 Coordinates of the 1st point in user space.
     * @param color1 Color at the 1st point.
     * @param x2,y2 Coordinates of the 2nd point in user space.
     * @param color2 Color at the 2nd point.
     */
    public GradientPaint(float x1,
             float y1,
             Color color1,
             float x2,
             float y2,
             Color color2) {
        p1 = new Point2D.Float(x1, y1);
        p2 = new Point2D.Float(x2, y2);
        this.color1 = color1;
        this.color2 = color2;
    }

    /**
     * Constructs a simple acyclic GradientPaint object.
     * @param pt1 Coordinates of the 1st point in user space.
     * @param color1 Color at the 1st point.
     * @param pt2 Coordinates of the 2nd point in user space.
     * @param color2 Color at the 2nd point.
     */
    public GradientPaint(Point2D pt1,
             Color color1,
             Point2D pt2,
             Color color2) {
        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 GradientPaint object
     * depending on the boolean parameter.
     * @param x1,y1 Coordinates of the 1st point in user space.
     * @param color1 Color at the 1st point.
     * @param x2,y2 Coordinates of the 2nd point in user space.
     * @param color2 Color at the 2nd point.
     * @param cyclic true if the gradient pattern should cycle
     * repeatedly between the two colors.
     */
    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 GradientPaint object
     * depending on the boolean parameter.
     * @param pt1 Coordinates of the 1st point in user space.
     * @param color1 Color at the 1st point.
     * @param pt2 Coordinates of the 2nd point in user space.
     * @param color2 Color at the 2nd point.
     * @param cyclic true if the gradient pattern should cycle
     * repeatedly between the two colors.
     */
    public GradientPaint(Point2D pt1,
             Color color1,
             Point2D pt2,
             Color color2,
             boolean cyclic) {
    this (pt1, color1, pt2, color2);
    this.cyclic = cyclic;
    }

    /**
     * Creates and returns a context used to generate the color pattern.
     * @param cm ColorModel in which the caller wishes to receive the
     * paint data. This is used only as a hint.
     * @param deviceBounds The rectangle describing the bounding box in
     * device space of the graphics primitive being rendered.
     * @param userBounds The rectangle describing the bounding box in
     * user space of the graphics primitive being rendered.
     * @param xform The Transform from user space into device space.
     * @return The PaintContext for generating color patterns.
     * @see PaintContext
     */
    public PaintContext createContext(ColorModel cm,
                      Rectangle deviceBounds,
                      Rectangle2D userBounds,
                      AffineTransform xform) {

        Point2D t1 = xform.transform(p1, null);
        Point2D t2 = xform.transform(p2, null);
        return (new GradientPaintContext(t1, t2, color1, color2, cyclic));
    }

    /**
     * Return the transparency mode for this GradientPaint.
     * @see Transparency
     */
    public int getTransparency() {
    int a1 = color1.getAlpha();
    int a2 = color2.getAlpha();
    return (((a1 & a2) == 0xff) ? OPAQUE : TRANSLUCENT);
    }

}