Author: Jeroen Zwartepoorte

Expand the list item so that the entire item is visible when the mouse hovers over a list item.

After reading the article on DataTips by Zafir Anjum i decided to write a component that provided this functionality in a JList. The result is JListEx. I had to write the class a little bit different from the JTableEx that Zafir wrote. I needed to know the size of the JScrollPane that contained the JList in order to determine wether a datatips was necessary. (if the width of the cell > the width of the JScrollPane then draw the datatip).

I welcome suggestions & bug reports to further improve the component.

/**
 * SwingEx Project<BR>
 *
 * This class is part of the Swing Extension Project. The goal of this project
 * is to provide Swing components with extra functionality that isn't available
 * in the standard Swing components from Sun.
 *
 * @author Jeroen Zwartepoorte (Jeroen@xs4all.nl)
 */
package SwingEx;

import java.awt.*;
import java.awt.event.MouseEvent;
import java.util.Vector;

// JFC 1.0.X
/*import com.sun.java.swing.*;
import com.sun.java.swing.event.ListSelectionListener;*/

// JFC 1.1.X
import javax.swing.*;
import javax.swing.event.ListSelectionListener;

/**
 * This component contains extended functionality that JList doesn't have. It's
 * written so that you only have to change your JList declaration from JList to
 * JListEx. The rest of the changes are transparent. These are the extra
 * functionalities: <BR>
 * <UL>
 * <LI><B>DataTips</B>: When a cell isn't completely visible, it displays a
 * JToolTip when the user holds the cursor over it.</LI>
 * <LI><B>JScrollPane</B>: In order for the datatips to work, JListEx is already
 * in a JScrollPane. You don't have to add JListEx to a scrollpane like you had
 * to do for JList. You can get access to the scrollpane by using the
 * getScrollPane() method.</LI></UL><BR>
 *
 * Any suggestions on extra functionality are welcome!
 *
 * @author Jeroen Zwartepoorte (Jeroen@xs4all.nl)
 * @author used source by Zafir Anjum (www.codeguru.com/java/articles/123.shtml)
 * @version 1.0
 */
public class JListEx extends JComponent
{
    // Private variables.
	private JScrollPane scrollpane = null;
    private JList list = null;
    private boolean bDataTips = false;

    /**
     * Parameterless constructor.
     */
	public JListEx()
	{
    	list = new JList() {
        	public String getToolTipText(MouseEvent event)
            {
            	return this_getToolTipText(event);
            }

            public Point getToolTipLocation(MouseEvent event)
            {
            	return this_getToolTipLocation(event);
            }
        };
    	init();
	}

    /**
     * Object array constructor.
     */
    public JListEx(final Object[] listData)
    {
    	list = new JList(listData) {
        	public String getToolTipText(MouseEvent event)
            {
            	return this_getToolTipText(event);
            }

            public Point getToolTipLocation(MouseEvent event)
            {
            	return this_getToolTipLocation(event);
            }
        };
    	init();
    }

    /**
     * Vector constructor.
     */
    public JListEx(final Vector listData)
    {
    	list = new JList(listData) {
        	public String getToolTipText(MouseEvent event)
            {
            	return this_getToolTipText(event);
            }

            public Point getToolTipLocation(MouseEvent event)
            {
            	return this_getToolTipLocation(event);
            }
        };
    	init();
    }

    /**
     * ListModel constructor.
     */
    public JListEx(ListModel dataModel)
    {
    	list = new JList(dataModel) {
        	public String getToolTipText(MouseEvent event)
            {
            	return this_getToolTipText(event);
            }

            public Point getToolTipLocation(MouseEvent event)
            {
            	return this_getToolTipLocation(event);
            }
        };
    	init();
    }

    /**
     * Intialize class variables. 
     */
    protected void init()
    {
    	this.setLayout(new BorderLayout());
    	scrollpane = new JScrollPane(list);
        this.add(scrollpane, BorderLayout.CENTER);
    }

    /**
     * Returns wether the datatips are enabled.
     */
    public boolean getDataTips()
    {
    	return bDataTips;
    }

    /**
     * Enable or disable datatips.
     */
    public void setDataTips(boolean bDataTips)
    {
    	this.bDataTips = bDataTips;
        if (bDataTips)
        	list.setToolTipText("text");
        else
        	list.setToolTipText("");
    }

    /**
     * Returns scrollpane that contains JList.
     */
    public JScrollPane getScrollPane()
    {
    	return scrollpane;
    }

    /**
     * This method is called when the JList is asked for the tooltip text.
     * JList.getToolTipText refers to this method. This method is declared here
     * because it needs access to the JScrollPane that the JList is in.
     */
    protected String this_getToolTipText(MouseEvent event)
    {
    	int idx = list.locationToIndex(event.getPoint());

        if (idx == -1)
        	return null;

        Object obj = list.getModel().getElementAt(idx);

        boolean bSelected = obj.equals(list.getSelectedValue());

        Component comp = list.getCellRenderer().getListCellRendererComponent(list,
        obj, idx, bSelected, bSelected);

        if (obj == null)
        	return null;
        if (obj.toString().equals(""))
        	return null;

        if (comp.getPreferredSize().width < scrollpane.getSize().width)
        {
        	return null;
        }

        return obj.toString();
    }

    /**
     * This method is called when the JList is asked for the position of the
     * tooltip. JList.getToolTipLocation refers to this method. This method is
     * declared here because it needs access to the JScrollPane that the JList
     * is in.
     */
    protected Point this_getToolTipLocation(MouseEvent event)
    {
    	int idx = list.locationToIndex(event.getPoint());

        if (idx == -1)
        	return null;

        Object obj = list.getModel().getElementAt(idx);
        
        boolean bSelected = obj.equals(list.getSelectedValue());

        Component comp = list.getCellRenderer().getListCellRendererComponent(list,
        obj, idx, bSelected, bSelected);

        if (obj == null)
        	return null;
        if (obj.toString().equals(""))
        	return null;

        if (comp.getPreferredSize().width < scrollpane.getSize().width)
        {
        	return null;
        }
            
        Point pt = list.getCellBounds(idx, idx).getLocation();
        if (pt == null)
        	return null;

        pt.translate(-2, -1);

        return pt;
    }

    /**
     * JList methods.
     *
     * These methods are declared here so that the programmer can use JListEx
     * like any normal JList. Since this class extends JComponent we need to
     * add all the public methods in JList here and call the appropriate method
     * in the JList.
     */
    public void addListSelectionListener(ListSelectionListener listener) {
    	list.addListSelectionListener(listener);
    }

    public void addSelectionInterval(int anchor, int lead) {
		list.addSelectionInterval(anchor, lead);
    }

    public void clearSelection() {
    	list.clearSelection();
    }

    public void ensureIndexIsVisible(int index) {
    	list.ensureIndexIsVisible(index);
    }

    public int getAnchorSelectionIndex() {
    	return list.getAnchorSelectionIndex();
    }
    
    public Rectangle getCellBounds(int index1, int index2) {
    	return list.getCellBounds(index1, index2);
    }

    public ListCellRenderer getCellRenderer() {
    	return list.getCellRenderer();
    }

    public int getFirstVisibleIndex() {
    	return list.getFirstVisibleIndex();
    }

    public int getFixedCellHeight() {
    	return list.getFixedCellHeight();
    }

    public int getFixedCellWidth() {
    	return list.getFixedCellWidth();
    }
    
    public int getLastVisibleIndex() {
    	return list.getLastVisibleIndex();
    }
    
    public int getLeadSelectionIndex() {
    	return list.getLeadSelectionIndex();
    }

    public int getMaxSelectionIndex() {
    	return list.getMaxSelectionIndex();
    }

    public int getMinSelectionIndex() {
    	return list.getMinSelectionIndex();
    }

    public ListModel getModel() {
    	return list.getModel();
    }

    public Dimension getPreferredScrollableViewportSize() {
    	return list.getPreferredScrollableViewportSize();
    }

    public Object getPrototypeCellValue() {
    	return list.getPrototypeCellValue();
    }

    public int getScrollableBlockIncrement(Rectangle visibleRect, int orientation, int direction) {
    	return list.getScrollableBlockIncrement(visibleRect, orientation, direction);
    }

    public boolean getScrollableTracksViewportHeight() {
    	return list.getScrollableTracksViewportHeight();
    }

    public boolean getScrollableTracksViewportWidth() {
    	return list.getScrollableTracksViewportWidth();
    }

    public int getScrollableUnitIncrement(Rectangle visibleRect, int orientation, int direction) {
    	return list.getScrollableUnitIncrement(visibleRect, orientation, direction);
    }
    
    public int getSelectedIndex() {
    	return list.getSelectedIndex();
    }

    public int[] getSelectedIndices() {
    	return list.getSelectedIndices();
    }

    public Object getSelectedValue() {
    	return list.getSelectedValue();
    }

    public Object[] getSelectedValues() {
    	return list.getSelectedValues();
    }

    public Color getSelectionBackground() {
    	return list.getSelectionBackground();
    }

    public Color getSelectionForeground() {
    	return list.getSelectionForeground();
    }

    public int getSelectionMode() {
    	return list.getSelectionMode();
    }

    public ListSelectionModel getSelectionModel() {
    	return list.getSelectionModel();
    }

    public boolean getValueIsAdjusting() {
    	return list.getValueIsAdjusting();
    }

    public int getVisibleRowCount() {
    	return list.getVisibleRowCount();
    }

    public Point indexToLocation(int index) {
    	return list.indexToLocation(index);
    }
    
    public boolean isSelectedIndex(int index) {
    	return list.isSelectedIndex(index);
    }

    public boolean isSelectionEmpty() {
    	return list.isSelectionEmpty();
    }

    public int locationToIndex(Point location) {
    	return list.locationToIndex(location);
    }

    public void removeListSelectionListener(ListSelectionListener listener) {
    	list.removeListSelectionListener(listener);
    }

    public void removeSelectionInterval(int index0, int index1) {
    	list.removeSelectionInterval(index0, index1);
    }

    public void setCellRenderer(ListCellRenderer cellRenderer) {
    	list.setCellRenderer(cellRenderer);
    }

    public void setFixedCellHeight(int height) {
    	list.setFixedCellHeight(height);
    }

    public void setFixedCellWidth(int width) {
    	list.setFixedCellWidth(width);
    }

    public void setListData(final Object[] listData) {
    	list.setListData(listData);
    }

    public void setListData(final Vector listData) {
    	list.setListData(listData);
    }

    public void setModel(ListModel model) {
    	list.setModel(model);
    }

    public void setPrototypeCellValue(Object prototypeCellValue) {
    	list.setPrototypeCellValue(prototypeCellValue);
    }

    public void setSelectedIndex(int index) {
    	list.setSelectedIndex(index);
    }

    public void setSelectedIndices(int[] indices) {
    	list.setSelectedIndices(indices);
    }

    public void setSelectedValue(Object anObject,boolean shouldScroll) {
    	list.setSelectedValue(anObject, shouldScroll);
    }

    public void setSelectionBackground(Color selectionBackground) {
    	list.setSelectionBackground(selectionBackground);
    }

    public void setSelectionForeground(Color selectionForeground) {
    	list.setSelectionForeground(selectionForeground);
    }

    public void setSelectionInterval(int anchor, int lead) {
    	list.setSelectionInterval(anchor, lead);
    }

    public void setSelectionMode(int selectionMode) {
    	list.setSelectionMode(selectionMode);
    }
    
    public void setSelectionModel(ListSelectionModel selectionModel) {
    	list.setSelectionModel(selectionModel);
    }
    
    public void setValueIsAdjusting(boolean b) {
    	list.setValueIsAdjusting(b);
    }
    
    public void setVisibleRowCount(int visibleRowCount) {
    	list.setVisibleRowCount(visibleRowCount);
    }
}

Posted On: 11-Feb-1999

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