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 * 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.
 *
 * 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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 */

/*
 * @test
 * @requires (os.family == "linux")
 * @key headful
 * @bug 8218469
 * @summary Tests JSlider is rendered properly with gtk3
 * @run main TestJSliderRendering
 */

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JSlider;
import javax.swing.SwingUtilities;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import java.awt.Color;
import java.awt.Component;
import java.awt.Point;
import java.awt.Rectangle;
import java.awt.Robot;

public class TestJSliderRendering {
    private static JFrame frame;
    private static JSlider slider;
    private static Point point;
    private static Rectangle rect;
    private static Robot robot;
    private static final String GTK_LAF_CLASS = "GTKLookAndFeel";
    private static int minColorDifference = 50;

    private static void blockTillDisplayed(Component comp) {
        Point p = null;
        while (p == null) {
            try {
                p = comp.getLocationOnScreen();
            } catch (IllegalStateException e) {
                try {
                    Thread.sleep(500);
                } catch (InterruptedException ie) {
                }
            }
        }
    }

    private static int getMaxColorDiff(Color c1, Color c2) {
        return Math.max(Math.abs(c1.getRed() - c2.getRed()),
                Math.max(Math.abs(c1.getGreen() - c2.getGreen()),
                        Math.abs(c1.getBlue() - c2.getBlue())));
    }

    public static void main(String[] args) throws Exception {
        if (!System.getProperty("os.name").startsWith("Linux")) {
            System.out.println("This test is meant for Linux platform only");
            return;
        }

        for (UIManager.LookAndFeelInfo lookAndFeelInfo :
                UIManager.getInstalledLookAndFeels()) {
            if (lookAndFeelInfo.getClassName().contains(GTK_LAF_CLASS)) {
                try {
                    UIManager.setLookAndFeel(lookAndFeelInfo.getClassName());
                } catch (final UnsupportedLookAndFeelException ignored) {
                    System.out.println("GTK L&F could not be set, so this " +
                            "test can not be run in this scenario ");
                    return;
                }
            }
        }

        robot = new Robot();
        robot.setAutoDelay(100);

        try {
            SwingUtilities.invokeAndWait(new Runnable() {
                public void run() {
                    JPanel panel = new JPanel();
                    slider = new JSlider(JSlider.HORIZONTAL, 0, 100, 50);
                    panel.add(slider);
                    frame = new JFrame("TestJSliderRendering");
                    frame.add(panel);
                    frame.setSize(400, 400);
                    frame.setAlwaysOnTop(true);
                    frame.setLocationRelativeTo(null);
                    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                    frame.setVisible(true);
                }
            });

            robot.waitForIdle();
            robot.delay(500);

            blockTillDisplayed(slider);
            SwingUtilities.invokeAndWait(() -> {
                point = slider.getLocationOnScreen();
                rect = slider.getBounds();
            });
            robot.waitForIdle();
            robot.delay(500);

            int h = point.y+rect.height*6/7;

            Color backgroundColor = robot
                    .getPixelColor(point.x+rect.width/4, h);
            robot.waitForIdle();

            boolean knobFound = false;
            for (int i=point.x+rect.width/4;i<point.x+rect.width*3/4;i+=2) {
                Color highlightColor = robot.getPixelColor(i, h);
                if (getMaxColorDiff(backgroundColor, highlightColor)
                        > minColorDifference) {
                    knobFound = true;
                    break;
                }
                robot.waitForIdle();
            }
            if (!knobFound) {
                throw new RuntimeException("The slider is not rendered properly");
            }
        } finally {
            if (frame != null) {
                SwingUtilities.invokeAndWait(frame::dispose);
            }
        }
    }
}