JTextPane - unwanted repainting

Question

I just want to simulate advanced text editors. I use the code below to implement special behaviour for viewing - scrollbar is longer(+ 75px from the bottom - caused by EmptyBorder) and the minimum distance(height) between jtextpane's border and the last text line is set to 20px(caused by overriden scrollRectToVisible)
Unfortunately it has unwanted side effect - if you type some text at the bottom of this jtextpane, press enter, so the line is painted below the minimum distance first and then it's repainted to the correct place(you can simulate it easily by pressing the enter at the jtextpane's bottom, you will see painting a caret below my required minimum distance and then its repainting to the new destination)
I would need to fix this problem.
import javax.swing.*;
import java.awt.*;
public class SimpleEditor {
     private static int TOP_MARGIN = 20;
     private static int BOTTOM_MARGIN = 20;
     private static class TweakedTextPane extends JTextPane {
          public void scrollRectToVisible(Rectangle aRect) {
               final Dimension extentSize = getVisibleRect().getSize();
               aRect.y = aRect.y - TOP_MARGIN;
               aRect.x = aRect.x - 0;
               aRect.height = Math.min(aRect.height + TOP_MARGIN + BOTTOM_MARGIN, extentSize.height);
               super.scrollRectToVisible(aRect);
     public static void main(String[] args) {
          final JFrame frame = new JFrame("Simple Editor");
          frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
          JTextPane textPane = new TweakedTextPane();
          textPane.setBorder(BorderFactory.createEmptyBorder(0, 20, 75, 0));
          frame.setContentPane(new JScrollPane(textPane));
          SwingUtilities.invokeLater(new Runnable() {
               public void run() {
                    frame.setSize(400, 300);
                    frame.show();
}Any suggestions are welcome
Thanks a lot
Vity

Answer 1

Never give up!
Try this tricky way:-)
regards,
Stas
import java.awt.*;
import javax.swing.*;
import javax.swing.text.*;
public class Test12 {
        private static int TOP_MARGIN = 20;
        private static int BOTTOM_MARGIN = 20;
        private static class TweakedTextPane extends JTextPane {
            public TweakedTextPane() {
                super();
                setDocument(new CustomDocument(this));
                public void scrollRectToVisible(Rectangle aRect) {
                        final Dimension extentSize = getVisibleRect().getSize();
                        aRect.y = aRect.y - TOP_MARGIN;
                        aRect.x = aRect.x - 0;
                        aRect.height = Math.min(aRect.height + TOP_MARGIN + BOTTOM_MARGIN, extentSize.height);
                        super.scrollRectToVisible(aRect);
                        if (hasFocus() && !getCaret().isVisible()) {
                            getCaret().setVisible(true);
        public static void main(String[] args) {
                final JFrame frame = new JFrame("Simple Editor");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                JTextPane textPane = new TweakedTextPane();
                textPane.setBorder(BorderFactory.createEmptyBorder(0, 20, 75, 0));
                frame.setContentPane(new JScrollPane(textPane));
                SwingUtilities.invokeLater(new Runnable() {
                        public void run() {
                                frame.setSize(400, 300);
                                frame.show();
class CustomDocument extends DefaultStyledDocument {
    JEditorPane owner;
    public CustomDocument(JEditorPane owner) {
        this.owner=owner;
    public void insertString(int offs, String str, AttributeSet a) throws BadLocationException {
        super.insertString(offs,str,a);
        if (offs==getLength()-1 && str.equals("\n")) {
            owner.getCaret().setVisible(false);
}