Trying to make a WrappingComboBox

Question

Inspired by a fairly straightforward WrappingList, I thought I'd try to make a Wrapping JScrollPane. The goal is a ScrollPane that automatically wraps the text inside it. I've just about got it, but I have one thing that's not working. If I just put the JTextArea{s} in as the Editor, then you lose the any text that doesn't fit inside whatever the initial size was. Instead, I put the JTextAreas inside a JScrollPane which works fine, except that I still have to determine the size of the JScrollPane in advance. I would like to make each Editor/JScrollPane start out with just a single line of text and expand until it reaches a certain small number of lines.
Here is my attempt at a WrappingComboBox
import java.awt.Component;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.Insets;
import java.awt.LayoutManager;
import java.awt.Rectangle;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.ComponentEvent;
import java.awt.event.ComponentListener;
import java.awt.event.InputMethodEvent;
import java.awt.event.InputMethodListener;
import java.util.Vector;
import javax.swing.BoxLayout;
import javax.swing.ComboBoxEditor;
import javax.swing.JComboBox;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JList;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.JViewport;
import javax.swing.ListCellRenderer;
import javax.swing.ScrollPaneConstants;
import javax.swing.SwingUtilities;
import javax.swing.event.EventListenerList;
import javax.swing.plaf.basic.BasicComboBoxUI;
import javax.swing.plaf.basic.BasicComboPopup;
import javax.swing.plaf.basic.ComboPopup;
import javax.swing.text.View;
import debibdup.ScrollablePanel.ScrollableSizeHint;
* @author jfolson
public class WrappingComboBox extends JComboBox {
     WrappingComboBox() {
          super();
          this.setUI(new WrappingComboBoxUI());
     WrappingComboBox(Vector<?> items) {
          super(items);
          this.setUI(new WrappingComboBoxUI());
     public static class WrappingComboBoxUI extends BasicComboBoxUI {
          WrappingHelper wrappingHelper;
          public WrappingComboBoxUI() {
               super();
          public WrappingHelper getWrappingHelper() {
               if (wrappingHelper == null)
                    wrappingHelper = new WrappingHelper();
               return wrappingHelper;
          /* Since my Editor, Renderer and Popup are not UIResources, I have to overload these methods
           * or else installUI would call BasicComboBoxUI.createXXX anyway and replace mine
          @Override
          protected ComboBoxEditor createEditor() {
               return new WrappingComboBoxEditor();
          /* See note for createEditor()
          @Override
          protected ListCellRenderer createRenderer() {
               return new WrappingList.WrappingListCellRenderer();
          /* See note for createEditor()
          @Override
          protected ComboPopup createPopup() {
               return new BasicComboPopup(comboBox) {
                    @Override
                    protected JList createList() {
                         // use the WrappingList for the popup to make it update its
                         // sizes
                         return new WrappingList(comboBox.getModel());
                         // BasicComboPopup overrides default, apparently fixes some
                         // bug but I can't use it because BasicGraphicsUtils
                         // functions are private
                         /*return new JList(comboBox.getModel()) {
                              @Override
                              public void processMouseEvent(MouseEvent e) {
                                   if (BasicGraphicsUtils.isMenuShortcutKeyDown(e)) {
                                        // Fix for 4234053. Filter out the Control Key
                                        // from the list.
                                        // ie., don't allow CTRL key deselection.
                                        Toolkit toolkit = Toolkit.getDefaultToolkit();
                                        e = new MouseEvent((Component) e.getSource(), e
                                                  .getID(), e.getWhen(), e.getModifiers()
                                                  ^ toolkit.getMenuShortcutKeyMask(), e
                                                  .getX(), e.getY(), e.getXOnScreen(), e
                                                  .getYOnScreen(), e.getClickCount(), e
                                                  .isPopupTrigger(), MouseEvent.NOBUTTON);
                                   super.processMouseEvent(e);
          /*Have to overrige getMinimumSize, rectangleForCurrentValue and layoutContainer in the Helper class
           * to make a smaller (reasonable) sized popup button, otherwise, for multi-line combobox you get
           *  ridiculously large buttons.
          @Override
          public Dimension getMinimumSize(JComponent c) {
               if (!isMinimumSizeDirty) {
                    return new Dimension(cachedMinimumSize);
               Dimension size = getDisplaySize();
               Insets insets = getInsets();
               // calculate the width and height of the button
               int buttonHeight = size.height;
               if (buttonHeight > arrowButton.getPreferredSize().width)
                    buttonHeight = arrowButton.getPreferredSize().width;
               int buttonWidth = arrowButton.getPreferredSize().width;
               // adjust the size based on the button width
               size.height += insets.top + insets.bottom;
               size.width += insets.left + insets.right + buttonWidth;
               cachedMinimumSize.setSize(size.width, size.height);
               isMinimumSizeDirty = false;
               return new Dimension(size);
           * Returns the area that is reserved for drawing the currently selected
           * item.
          @Override
          protected Rectangle rectangleForCurrentValue() {
               int width = comboBox.getWidth();
               int height = comboBox.getHeight();
               Insets insets = getInsets();
               int buttonSize = height - (insets.top + insets.bottom);
               if (arrowButton != null) {
                    buttonSize = arrowButton.getWidth();
               if (true) {// BasicGraphicsUtils.isLeftToRight(comboBox)) { // this
                    // method is not visible
                    return new Rectangle(insets.left, insets.top, width
                              - (insets.left + insets.right + buttonSize), height
                              - (insets.top + insets.bottom));
               } else { // if I could tell, put the box on the other side for right
                    // to left checkboxes
                    return new Rectangle(insets.left + buttonSize, insets.top,
                              width - (insets.left + insets.right + buttonSize),
                              height - (insets.top + insets.bottom));
          @Override
          protected LayoutManager createLayoutManager() {
               return getWrappingHelper();
          private class WrappingHelper implements LayoutManager {
               // LayoutManager
               /* Need to override layoutContainer to put in a smaller popup button
               public void addLayoutComponent(String name, Component comp) {} // Can't
               // do
               // this
               public void removeLayoutComponent(Component comp) {}
               public Dimension preferredLayoutSize(Container parent) {
                    return parent.getPreferredSize();
               public Dimension minimumLayoutSize(Container parent) {
                    return parent.getMinimumSize();
               public void layoutContainer(Container parent) {
                    JComboBox cb = (JComboBox) parent;
                    int width = cb.getWidth();
                    int height = cb.getHeight();
                    Insets insets = getInsets();
                    int buttonHeight = height - (insets.top + insets.bottom);
                    int buttonWidth = buttonHeight;
                    if (arrowButton != null) {
                         if (buttonHeight > arrowButton.getPreferredSize().width)
                              buttonHeight = arrowButton.getPreferredSize().width;
                         Insets arrowInsets = arrowButton.getInsets();
                         buttonWidth = arrowButton.getPreferredSize().width
                                   + arrowInsets.left + arrowInsets.right;
                    Rectangle cvb;
                    if (arrowButton != null) {
                         if (true) {// BasicGraphicsUtils.isLeftToRight(cb)) { //
                              // this method is not visible
                              arrowButton.setBounds(width
                                        - (insets.right + buttonWidth), insets.top,
                                        buttonWidth, buttonHeight);
                         } else { // if I could tell, put the box on the other side
                              // for right to left checkboxes
                              arrowButton.setBounds(insets.left, insets.top,
                                        buttonWidth, buttonHeight);
                    if (editor != null) {
                         cvb = rectangleForCurrentValue();
                         editor.setBounds(cvb);
     public static class WrappingComboBoxEditor extends JScrollPane implements
               ComboBoxEditor, ComponentListener {
          EventListenerList listenerList = new EventListenerList();
          LineAwareTextArea text;
          public WrappingComboBoxEditor() {
               super();
               this.text = new LineAwareTextArea();
               this.setViewportView(text);
               setHorizontalScrollBarPolicy(ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER);
               setPreferredSize(new Dimension(100, 30));
               this.setItem("");
               text.setLineWrap(true);
               text.setWrapStyleWord(false);
               text.setEditable(true);
               text.addInputMethodListener(new InputMethodListener() {
                    @Override
                    public void caretPositionChanged(InputMethodEvent arg0) {}
                    @Override
                    public void inputMethodTextChanged(InputMethodEvent arg0) {
                         Object[] listeners = WrappingComboBoxEditor.this.listenerList
                                   .getListenerList();
                         // Process the listeners last to first, notifying
                         // those that are interested in this event
                         ActionEvent actionEvent = null;
                         for (int i = listeners.length - 2; i >= 0; i -= 2) {
                              if (listeners[i] == ActionListener.class) {
                                   if (actionEvent == null)
                                        actionEvent = new ActionEvent(this,
                                                  ActionEvent.ACTION_PERFORMED, null);
                                   ((ActionListener) listeners[i + 1])
                                             .actionPerformed(actionEvent);
               text.addComponentListener(this);
          @Override
          public void addActionListener(ActionListener l) {
               listenerList.add(ActionListener.class, l);
          @Override
          public Component getEditorComponent() {
               return this;
          @Override
          public Object getItem() {
               return text.getText();
          @Override
          public void removeActionListener(ActionListener l) {
               listenerList.remove(ActionListener.class, l);
          @Override
          public void setItem(Object anObject) {
               if (anObject == null)
                    text.setText("");
               else
                    text.setText(String.valueOf(anObject));
          @Override
          public void selectAll() {
               text.selectAll();
          public void componentHidden(ComponentEvent arg0) {}
          public void componentMoved(ComponentEvent arg0) {}
          @Override
          public void componentResized(ComponentEvent arg0) {
               JViewport view = this.getViewport();
               Dimension viewDim = view.getExtentSize();
               Insets insets = view.getInsets();
               System.out.println("actual view height: " + viewDim.height);
               Dimension wantDim = text.getPreferredScrollableViewportSize();
               if (wantDim.height > viewDim.height) {
                    viewDim.height = wantDim.height + insets.top + insets.bottom;
                    view.setPreferredSize(viewDim);
                    view.revalidate();
                    ((JComponent) this.getParent()).revalidate();
                    //SwingUtilities.windowForComponent(this).pack(); //even this doesn't work
          @Override
          public void componentShown(ComponentEvent arg0) {}
      * Only really need to expose rowHeight but might as well determine the
      * correct size it wants its viewport
      * @author jfolson
     public static class LineAwareTextArea extends JTextArea {
          private int maxVisibleRows = 3;
          public LineAwareTextArea() {
               super();
          public LineAwareTextArea(String text) {
               this();
               setText(text);
          @Override
          public Dimension getPreferredScrollableViewportSize() {
               Dimension d = this.getPreferredSize();
               float hspan = getWidth();
               View view = (getUI()).getRootView(this);
               view.setSize(hspan, Float.MAX_VALUE);
               float vspan = view.getPreferredSpan(View.Y_AXIS);
               Insets insets = getInsets();
               int rows = (d.height / this.getRowHeight());
               if (rows > maxVisibleRows)
                    rows = maxVisibleRows;
               d.height = rows * getRowHeight() + insets.top + insets.bottom;
               System.out.println("prefer view height: " + d.height + " (" + rows
                         + " line(s))");  // this is here just so I can see that it's getting the right number of desired lines.
               return d;
          public void setMaxVisibleRows(int rows) {
               this.maxVisibleRows = rows;
          public int getMaxVisibleRows() {
               return this.maxVisibleRows;
     public static class ComboTest extends JFrame {
          public ComboTest() {
               setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
               init();
               pack();
               show();
          private void init() {
               ScrollablePanel mainPanel = new ScrollablePanel();
               mainPanel.setScrollableWidth(ScrollableSizeHint.FIT);
               mainPanel.setLayout(new BoxLayout(mainPanel, BoxLayout.Y_AXIS));
               ScrollablePanel fieldPanel = new ScrollablePanel();
               fieldPanel.setLayout(new BoxLayout(fieldPanel, BoxLayout.X_AXIS));
               fieldPanel.setScrollableWidth(ScrollableSizeHint.FIT);
               Vector<String> items = new Vector<String>();
               items.add("Item One");
               JComboBox list = new WrappingComboBox(items);
               list.setEditable(true);
               JLabel fieldLabel = new JLabel("Label: ");
               fieldLabel.setAlignmentY(TOP_ALIGNMENT);
               list.setAlignmentY(TOP_ALIGNMENT);
               fieldPanel.add(fieldLabel);
               fieldPanel.add(list);
               mainPanel.add(fieldPanel);
               fieldPanel = new ScrollablePanel();
               fieldPanel.setLayout(new BoxLayout(fieldPanel, BoxLayout.X_AXIS));
               fieldPanel.setScrollableWidth(ScrollableSizeHint.FIT);
               items
                         .add("Item Two content content content content Item Two content content content content Item Two content content content content Item Two content content content content");
               list = new WrappingComboBox(items);
               list.setEditable(true);
               fieldLabel = new JLabel("Label: ");
               fieldLabel.setAlignmentY(TOP_ALIGNMENT);
               list.setAlignmentY(TOP_ALIGNMENT);
               fieldPanel.add(fieldLabel);
               fieldPanel.add(list);
               mainPanel.add(fieldPanel);
               JScrollPane mainScrolls = new JScrollPane(mainPanel,
                         JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED,
                         JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);
               mainScrolls.setPreferredSize(new Dimension(200, 200));
               setContentPane(mainScrolls);
     public static void main(String[] args) {
          new ComboTest();
}And here is the WrappingList that it references
import java.awt.Component;
import java.awt.Dimension;
import java.awt.Insets;
import javax.swing.JFrame;
import javax.swing.JList;
import javax.swing.JScrollPane;
import javax.swing.JTextPane;
import javax.swing.ListCellRenderer;
import javax.swing.ListModel;
import javax.swing.border.EmptyBorder;
import javax.swing.plaf.basic.BasicListUI;
import javax.swing.text.View;
* List that wraps its text! Whenever the list's layout (e.g. size) changes the
* list's UI is instructed to update its layout too.
public class WrappingList extends JList {
     public WrappingList() {
          setUI(new WrappingListUI());
          setCellRenderer(new WrappingListCellRenderer());
     public WrappingList(ListModel model) {
          super(model);
          setUI(new WrappingListUI());
          setCellRenderer(new WrappingListCellRenderer());
     @Override
     public void doLayout() {
          ((WrappingListUI) getUI()).updateLayoutState();
          super.doLayout();
     @Override
     public boolean getScrollableTracksViewportWidth() {
          return true;
      * ListUI implementation that exposes the method for updating its layout
     private static class WrappingListUI extends BasicListUI {
          @Override
          public void updateLayoutState() {
               super.updateLayoutState();
      * List cell renderer that uses the list's width to alter its preferred size
      * TODO - override bound properties in the same way as
      * DefaultListCellRenderer
     public static class WrappingListCellRenderer extends JTextPane implements
               ListCellRenderer {
          public WrappingListCellRenderer() {
               setBorder(new EmptyBorder(1, 1, 1, 1));
          public Component getListCellRendererComponent(JList list, Object value,
                    int index, boolean selected, boolean hasFocus) {
               setBackground(selected ? list.getSelectionBackground() : list
                         .getBackground());
               setForeground(selected ? list.getSelectionForeground() : list
                         .getForeground());
               // TODO - border, font etc.
               setText(String.valueOf(value));
               float hspan = list.getWidth();
               View view = (getUI()).getRootView(this);
               view.setSize(hspan, Float.MAX_VALUE);
               float vspan = view.getPreferredSpan(View.Y_AXIS);
               Insets insets = getInsets();
               setPreferredSize(new Dimension(insets.left + insets.right
                         + (int) hspan, insets.top + insets.bottom + (int) vspan));
               return this;
     public static void main(String[] args) {
          new Test();
     public static class Test extends JFrame {
          public Test() {
               setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
               init();
               pack();
               show();
          private void init() {
               JList list = new WrappingList();
               list
                         .setListData(new Object[] {
                                   "Item One",
                                   "Item Two content content content content Item Two content content content content Item Two content content content content Item Two content content content content" });
               setContentPane(new JScrollPane(list,
                         JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED,
                         JScrollPane.HORIZONTAL_SCROLLBAR_NEVER));
}You can verify (in System.out) that the preferred size is larger than the actual default size once you switch to the longer value in the combo box, but the actual size doesn't change. I've tried setSize, setMinimumSize, nothing makes the JScrollPane/Editor any larger. I've also tried calling and not calling various combinations of revalidate(), getParent().revalidate() and getViewport().revalidate(). What am I missing?
Edited by: inspired2apathy on Oct 16, 2010 7:22 PM

Answer 1

inspired2apathy wrote:
... The goal is a ScrollPane that automatically wraps the text inside it. I've just about got it, but I have one thing that's not working. If I just put the JTextArea{s} in as the Editor, then you lose the any text that doesn't fit inside whatever the initial size was. Instead, I put the JTextAreas inside a JScrollPane which works fine, except that I still have to determine the size of the JScrollPane in advance. I would like to make each Editor/JScrollPane start out with just a single line of text and expand until it reaches a certain small number of lines.
... What am I missing?THE BASICS. See if this isn't what you are trying to do.
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
public class Test
  public static void main(String[] args) {
    JTextArea ta = new JTextArea();
    ta.setLineWrap(true);
    ta.setWrapStyleWord(true);
    JScrollPane sp = new JScrollPane(ta);
    JFrame f = new JFrame();
    f.getContentPane().add(sp, "Center");
    f.setBounds(0, 0, 400, 300);
    f.setDefaultCloseOperation(f.EXIT_ON_CLOSE);
    f.setVisible(true); 
}OP, your code was too long and complicated for me to compile and run. However, aren't you forgetting the two simple methods <tt>JTextArea.setLineWrap()</tt> and <tt>JTextArea.setWrapStyleWord()</tt>? Furthermore, I absolutely see no need for you to extend SWING components for demonstration this simple -- that is, if I understand your problem correctly.