001/* ===========================================================
002 * JFreeChart : a free chart library for the Java(tm) platform
003 * ===========================================================
004 *
005 * (C) Copyright 2000-2022, by David Gilbert and Contributors.
006 *
007 * Project Info:  http://www.jfree.org/jfreechart/index.html
008 *
009 * This library is free software; you can redistribute it and/or modify it
010 * under the terms of the GNU Lesser General Public License as published by
011 * the Free Software Foundation; either version 2.1 of the License, or
012 * (at your option) any later version.
013 *
014 * This library is distributed in the hope that it will be useful, but
015 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
016 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
017 * License for more details.
018 *
019 * You should have received a copy of the GNU Lesser General Public
020 * License along with this library; if not, write to the Free Software
021 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
022 * USA.
023 *
024 * [Oracle and Java are registered trademarks of Oracle and/or its affiliates. 
025 * Other names may be trademarks of their respective owners.]
026 *
027 * ----------------------------------------
028 * DirectionalGradientPaintTransformer.java
029 * ----------------------------------------
030 * (C) Copyright 2013-2021 by Peter Kolb and Contributors.
031 *
032 * Original Author:  Peter Kolb;
033 * Contributor(s):   David Gilbert;
034 *
035 */
036
037package org.jfree.chart.util;
038
039import java.awt.GradientPaint;
040import java.awt.geom.Rectangle2D;
041import java.awt.Shape;
042
043/**
044 * Transforms a {@code GradientPaint} to range over the width of a target 
045 * shape.  The orientation of the resulting {@code GradientPaint}
046 * depend on the coordinates of the original paint:
047 *
048 * <ul>
049 * <li> If the original paint starts at 0,0 and ends at a point 0, y != 0,
050 * the resulting paint will have a vertical orientation.
051 * <li> If the original paint starts at 0,0 and ends at a point x !=0, 0,
052 * the resulting paint will have a horizontal orientation.
053 * <li> If the original paint starts at 0,0 and ends at a point x != 0, y != 0,
054 * the resulting paint will have a diagonal orientation from the upper left to
055 * the lower right edge. Lines of equal color will have a 45 ∞ angle,
056 * pointing upwards from left to right.
057 * <li> If the original paint starts at a point x != 0, y != 0,
058 * the resulting paint will have a diagonal orientation from the lower left to
059 * the upper right edge. Lines of equal color will have a 45 ∞ angle,
060 * pointing downwards from left to right.
061 * </ul>
062 * <p>In all cases, the cyclic flag of the original paint will be taken into 
063 * account.</p>
064 */
065public class DirectionalGradientPaintTransformer implements GradientPaintTransformer {
066    
067    /**
068     * Default constructor.
069     */
070    public DirectionalGradientPaintTransformer() {
071        super();    
072    }
073    
074    /**
075     * Transforms a {@code GradientPaint} instance to fit some target 
076     * shape.
077     * 
078     * @param paint  the original paint (not {@code null}).
079     * @param target  the reference area (not {@code null}).
080     * 
081     * @return A transformed paint.
082     */
083    @Override
084    public GradientPaint transform(GradientPaint paint, Shape target) {
085        //get the coordinates of the original GradientPaint
086        final double px1 = paint.getPoint1().getX();
087        final double py1 = paint.getPoint1().getY();
088        final double px2 = paint.getPoint2().getX();
089        final double py2 = paint.getPoint2().getY();
090        //get the coordinates of the shape that is to be filled
091        final Rectangle2D bounds = target.getBounds();
092        final float bx = (float)bounds.getX();
093        final float by = (float)bounds.getY();
094        final float bw = (float)bounds.getWidth();
095        final float bh = (float)bounds.getHeight();
096        //reserve variables to store the coordinates of the resulting GradientPaint
097        float rx1, ry1, rx2, ry2;
098        if (px1 == 0 && py1 == 0) {
099            //start point is upper left corner
100            rx1 = bx;
101            ry1 = by;
102            if (px2 != 0.0f && py2 != 0.0f) {
103                //end point is lower right corner --> diagonal gradient
104                float offset = (paint.isCyclic()) ? (bw + bh) / 4.0f 
105                        : (bw + bh) / 2.0f ;
106                rx2 = bx + offset;
107                ry2 = by + offset;
108            }
109            else {
110                //end point is either lower left corner --> vertical gradient
111                //or end point is upper right corner --> horizontal gradient
112                rx2 = (px2 == 0) ? rx1 : (paint.isCyclic() ? (rx1 + bw / 2.0f) 
113                        : (rx1 + bw));
114                ry2 = (py2 == 0) ? ry1 : (paint.isCyclic() ? (ry1 + bh / 2.0f) 
115                        : (ry1 + bh));
116            }
117        }
118        else {
119            //start point is lower left right corner --> diagonal gradient
120            rx1 = bx;
121            ry1 = by + bh;
122            float offset = (paint.isCyclic()) ? (bw + bh) / 4.0f 
123                    : (bw + bh) / 2.0f;
124            rx2 = bx + offset;
125            ry2 = by + bh - offset;
126        }
127        return new GradientPaint(rx1, ry1, paint.getColor1(), rx2, ry2, 
128                paint.getColor2(), paint.isCyclic());
129    }
130}