test/jdk/java/awt/ScrollPane/ScrollPanechildViewportTest.java

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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/*
 * @test
 * @bug 4094581
 * @summary ScrollPane does not refresh properly when child is just smaller than viewport
 * @library /java/awt/regtesthelpers
 * @build PassFailJFrame
 * @run main/manual ScrollPanechildViewportTest
 */

import java.awt.Button;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Frame;
import java.awt.Panel;
import java.awt.ScrollPane;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

public class ScrollPanechildViewportTest {
    public static void main(String[] args) throws Exception {
        String INSTRUCTIONS = """
                1. Click "Slightly Large" and ensure scrollbars are VISIBLE
                2. Click "Slightly Small" and ensure there are NO scrollbars
                3. Click "Smaller" and ensure there are NO scrollbars
                4. If everything is ok, click PASS, else click FAIL.
                                          """;
        PassFailJFrame.builder()
                .title("Test Instructions")
                .instructions(INSTRUCTIONS)
                .columns(35)
                .testUI(ScrollPanechildViewportTest::initialize)
                .build()
                .awaitAndCheck();
    }

    static Frame initialize() {
        return new Test();
    }
}

class Test extends Frame implements ActionListener {
    Button b1, b2, b3;
    MyPanel p;
    int state; // 0 = slightly large, 1 = slightly smaller, 2 = smaller

    public Test() {
        ScrollPane sp = new ScrollPane();
        p = new MyPanel();
        p.setBackground(Color.yellow);
        state = 1;
        sp.add(p);
        add(sp, "Center");

        Panel p1 = new Panel();
        b1 = new Button("Slightly Large");
        b1.addActionListener(this);
        p1.add(b1);
        b2 = new Button("Slightly Small");
        b2.addActionListener(this);
        p1.add(b2);
        b3 = new Button("Smaller");
        b3.addActionListener(this);
        p1.add(b3);

        add(p1, "South");

        setSize(400, 200);
        //added to test to move test frame away from instructions
        setLocation(0, 350);
    }

    public void actionPerformed(ActionEvent e) {
        Object source = e.getSource();

        // set size to small and re-validate the panel to get correct size of
        // scrollpane viewport without scrollbars

        state = 2;
        p.invalidate();
        validate();

        Dimension pd = ((ScrollPane) p.getParent()).getViewportSize();

        if (source.equals(b1)) {
            p.setBackground(Color.green);
            state = 0;
        } else if (source.equals(b2)) {
            p.setBackground(Color.yellow);
            state = 1;
        } else if (source.equals(b3)) {
            p.setBackground(Color.red);
            state = 2;
        }

        p.invalidate();
        validate();
        System.out.println("Panel Size = " + p.getSize());
        System.out.println("ScrollPane Viewport Size = " + pd);
        System.out.println(" ");
    }

    class MyPanel extends Panel {
        public Dimension getPreferredSize() {
            Dimension d = null;
            Dimension pd = ((ScrollPane) getParent()).getViewportSize();
            switch (state) {
                case 0 -> {
                    d = new Dimension(pd.width + 2, pd.height + 2);
                    System.out.println("Preferred size: " + d);
                }
                case 1 -> {
                    d = new Dimension(pd.width - 2, pd.height - 2);
                    System.out.println("Preferred size: " + d);
                }
                case 2 -> {
                    d = new Dimension(50, 50);
                    System.out.println("Preferred size: " + d);
                }
            }
            return d;
        }
    }
}