Vertical Scrolling and Horizontal Wrapping in a JEditorPane

Question

Hey guys,
Some of you may recall my [post |http://forums.sun.com/thread.jspa?threadID=5418688] from a couple weeks back. In it, I learned how to force (or appear to force) the text of a JEditorPane to grow from the bottom-up instead of top-down (picture the difference between how a chat window grows to how a word document grows). The solution (which solves my original problem perfectly) involves simply placing the JEditorPane into the South region of a JPanel.
That was all fine and dandy, until I tried putting long lines of text into the JEditorPane. It scrolled vertically when it should have, but the text simply ran off the right side of the JEditorPane instead of wrapping (or showing a horizontal scrollbar).
After a gross amount of googling, I finally came across this old [post |http://forums.sun.com/thread.jspa?threadID=5318664] that seems to be related to my problem here. It hinted that I should set the width of the JPanel to match the width of the JScrollPane's Viewport. While that does indeed fix the problem with horizontal wrapping, it now creates a problem with the vertical scrolling (which works fine without the fix for horizontal wrapping)!
I've tried setting the preferred height of the JPanel to just about everything I can think of: the height of the viewport, extremely large numbers, negative numbers, zero, itself, the height of the JEditorPane. But they all do the same thing: no vertical scrollbar ever pops up, even when the text is obviously too long to fit in the window.
Here's an SSCCE demonstrating what I'm talking about:
import javax.swing.*;
import java.awt.*;
public class EditorPaneTest {
    public EditorPaneTest() {
         JFrame frame = new JFrame("EditorPane Test");
         frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
         JEditorPane textComponent = new JEditorPane();
         textComponent.setContentType("text/html");
         String text =
              "This sentence should wrap and not cause the horiztonal scroll bar to display.<br/>"
              + "<br/>This<br/>sentence<br/>should<br/>cause<br/>"
              + "the<br/>vertical<br/>scroll<br/>bar<br/>to<br/>display.<br/>";
         textComponent.setText(text);
         JPanel panel = new JPanel(new BorderLayout());
         //the purpose of putting the JEditorPane in a JPanel
         //is to force it to the bottom with BorderLayout
         panel.add(textComponent, BorderLayout.SOUTH);
         JScrollPane scrollPane = new JScrollPane(panel, JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED, JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);
         //this line enables wrapping
         //but disables vertical scrolling
         //(comment it out to switch)
         panel.setPreferredSize(new Dimension(scrollPane.getViewport().getWidth(), scrollPane.getViewport().getHeight()));
         frame.add(scrollPane);
         frame.setSize(100, 200);
         frame.setVisible(true);
    public static void main(String[] args) {
        new EditorPaneTest();
}As always, any pointers / suggestions / criticisms you can give me are greatly appreciated.
Thanks again,
Kevin

Answer 1

camickr wrote:
You need create a custom panel that implements the Scrollable interface. The key method to override to give you the behaviour you desire is the getScrollTracksViewportWidth() to return "true". This effectively fixes the width of the JEditorPane to the width of the viewport to wrapping is done as expected.That does handle the wrapping and scrolling, but it breaks the original problem: keeping a JEditorPane at the bottom of a JPanel. Using the ScrollablePanel you posted, the JEditorPane now stays at the top of the Panel instead of growing from the bottom.
To see what I'm talking about, check out this code (the only difference between this and the previous code is the addition of your suggestion):
import javax.swing.*;
import java.awt.*;
public class EditorPaneTest {
    public EditorPaneTest() {
         JFrame frame = new JFrame("EditorPane Test");
         frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
         JEditorPane textComponent = new JEditorPane();
         textComponent.setContentType("text/html");
         String text =
              "This sentence should wrap and not cause the horiztonal scroll bar to display.<br/>"
              + "<br/>This<br/>sentence<br/>should<br/>cause<br/>"
              + "the<br/>vertical<br/>scroll<br/>bar<br/>to<br/>display.<br/>";
         textComponent.setText(text);
         ScrollablePanel panel = new ScrollablePanel();
         panel.setLayout(new BorderLayout());
         //the purpose of putting the JEditorPane in a JPanel
         //is to force it to the bottom with BorderLayout
         panel.add(textComponent, BorderLayout.SOUTH);
         JScrollPane scrollPane = new JScrollPane(panel, JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED, JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);
         //this line enables wrapping
         //but disables vertical scrolling
         //(comment it out to switch)
        //panel.setPreferredSize(new Dimension(scrollPane.getViewport().getWidth(), scrollPane.getViewport().getHeight()));
         frame.add(scrollPane);
         frame.setSize(100, 200);
         frame.setVisible(true);
    public static void main(String[] args) {
        new EditorPaneTest();
     public class ScrollablePanel extends JPanel
          implements Scrollable
          public Dimension getPreferredScrollableViewportSize()
               return getPreferredSize();
          public int getScrollableUnitIncrement(
               Rectangle visibleRect, int orientation, int direction)
               return 20;
          public int getScrollableBlockIncrement(
               Rectangle visibleRect, int orientation, int direction)
               return 60;
          public boolean getScrollableTracksViewportWidth()
               return true;
          public boolean getScrollableTracksViewportHeight()
               return false;
}Resize the window to make it taller. The text should stay at the bottom of the window, but now it stays at the top. I tried using a BoxLayout on the ScrollablePanel instead, and adding a Box.createGlue( ) before adding the JEditorPane. But that didn't change anything.