Quelle  TestTabSize.java

/*
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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
 * 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).
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/**
 * @test
 * @bug 8187957
 * @summary  Verifies Tab Size works correctly in JTextArea
 * @key headful
 * @run main TestTabSize
 */

import java.awt.geom.Rectangle2D;
import javax.swing.GroupLayout;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.SwingUtilities;
import javax.swing.text.BadLocationException;
import javax.swing.text.Caret;

public class TestTabSize {
    private static JScrollPane jScrollPane1;
    private static JTextArea jTextArea1;
    private static JFrame f;
    private static Rectangle2D rect;
    private static Rectangle2D rect1;
    private static boolean excpnthrown = false;

    public static void main(String args[]) throws Exception {

        SwingUtilities.invokeAndWait(() -> {
            try {
                jScrollPane1 = new javax.swing.JScrollPane();
                jTextArea1 = new javax.swing.JTextArea();
                jTextArea1.setTabSize(8);
                f = new JFrame();

                jTextArea1.setFont(new java.awt.Font("Monospaced", 0, 10));
                String str =
                        "!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!#\n"
                        + "! Some Text\t\t\t\t\t#";
                jTextArea1.setText(str);
                jScrollPane1.setViewportView(jTextArea1);

                GroupLayout layout = new javax.swing.GroupLayout(f.getContentPane());
                f.getContentPane().setLayout(layout);
                layout.setHorizontalGroup(
                    layout.createParallelGroup(
                            javax.swing.GroupLayout.Alignment.LEADING)
                            .addGroup(layout.createSequentialGroup()
                                    .addContainerGap()
                                    .addComponent(jScrollPane1,
                                            javax.swing.GroupLayout.DEFAULT_SIZE,
                                            446, Short.MAX_VALUE)
                                    .addContainerGap())
                );
                layout.setVerticalGroup(
                        layout.createParallelGroup(
                                javax.swing.GroupLayout.Alignment.LEADING)
                                .addGroup(layout.createSequentialGroup()
                                        .addContainerGap()
                                        .addComponent(jScrollPane1)
                                        .addContainerGap())
                );

                f.pack();
                int first = str.indexOf("#");
                jTextArea1.setCaretPosition(first);
                Caret caret = jTextArea1.getCaret();
                rect = jTextArea1.modelToView2D(caret.getDot());
                System.out.println("caret x position " + rect.getX());

                jTextArea1.setCaretPosition(str.indexOf("#", first+1));
                caret = jTextArea1.getCaret();
                rect1 = jTextArea1.modelToView2D(caret.getDot());
                System.out.println("2nd caret x position " + rect1.getX());

            } catch (BadLocationException ex) {
                excpnthrown = true;
            } finally {
                if (f != null) {
                    f.dispose();
                }
            }
        });
        if (excpnthrown) {
            throw new RuntimeException("BadLocationException thrown");
        }
        if ((int)rect.getX() != (int)rect1.getX()) {
            throw new RuntimeException("Tab width calculation wrong");
        }
    }
}