test/jdk/java/awt/GradientPaint/JerkyGradient.java

/*
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * 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
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 *
 * 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).
 *
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 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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 */

/*
 * @test
 * @bug 4221201
 * @summary Test where the gradient drawn should remain in sync with the
 *          rotating rectangle.
 * @library /java/awt/regtesthelpers
 * @build PassFailJFrame
 * @run main/manual JerkyGradient
 */

import java.awt.Color;
import java.awt.Frame;
import java.awt.GradientPaint;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Paint;
import java.awt.Panel;
import java.awt.RenderingHints;
import java.awt.Shape;
import java.awt.geom.Rectangle2D;
import java.awt.image.BufferedImage;

public class JerkyGradient extends Panel implements Runnable {
    protected static Shape mShape;
    protected static Paint mPaint;
    protected static double mTheta;
    static Thread animatorThread;
    static BufferedImage mImg;

    public static void main(String[] args) throws Exception {
        String INSTRUCTIONS = """
                Watch at least one full rotation of the rectangle. Check that
                the gradient drawn remains in sync with the rotating
                rectangle. If so, pass this test. Otherwise, fail this test.
                """;

        PassFailJFrame.builder()
                .title("Test Instructions")
                .instructions(INSTRUCTIONS)
                .columns(35)
                .testUI(JerkyGradient::createUI)
                .build()
                .awaitAndCheck();
    }

    public static Frame createUI() {
        Frame f = new Frame("Rotating Gradient Test");
        JerkyGradient jg = new JerkyGradient();
        f.add(jg);
        f.setSize(200, 200);
        return f;
    }

    public JerkyGradient() {
        mShape = new Rectangle2D.Double(60, 50, 80, 100);
        mPaint = new GradientPaint(0, 0, Color.red,
                25, 25, Color.yellow,
                true);
        mImg = new BufferedImage(200, 200, BufferedImage.TYPE_INT_RGB);

        animatorThread = new Thread(this);
        animatorThread.setPriority(Thread.MIN_PRIORITY);
        animatorThread.start();
    }

    public synchronized void run() {
        Thread me = Thread.currentThread();
        double increment = Math.PI / 36;
        double twoPI = Math.PI * 2;

        while (animatorThread == me) {
            mTheta = (mTheta + increment) % twoPI;
            repaint();
            try {
                wait(50);
            } catch (InterruptedException ie) {
                break;
            }
        }
    }

    public void update(Graphics g) {
        Graphics2D g2 = mImg.createGraphics();
        g2.setColor(getBackground());
        g2.fillRect(0, 0, 200, 200);
        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                            RenderingHints.VALUE_ANTIALIAS_ON);
        g2.rotate(mTheta, 100, 100);
        g2.setPaint(Color.black);
        g2.drawLine(100, 30, 100, 55);
        g2.setPaint(mPaint);
        g2.fill(mShape);
        g2.setPaint(Color.black);
        g2.draw(mShape);
        paint(g);
        g2.dispose();
    }

    public void paint(Graphics g) {
        g.drawImage(mImg, 0, 0, null);
    }
}