JMultiLineToolTip.java

package uk.ac.rhul.cs.cl1.ui;

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;

import javax.swing.BorderFactory;
import javax.swing.CellRendererPane;
import javax.swing.JComponent;
import javax.swing.JTextArea;
import javax.swing.JToolTip;
import javax.swing.border.Border;
import javax.swing.border.CompoundBorder;
import javax.swing.plaf.ComponentUI;
import javax.swing.plaf.basic.BasicToolTipUI;

/**
 * Tooltip class that can wrap the tooltip text into multiple lines.
 * 
 * Based on the JMultiLineToolTip class of Zafir Anjum, see the following URL:
 * http://www.codeguru.com/java/articles/122.shtml
 * 
 * @author tamas
 *
 */
public class JMultiLineToolTip extends JToolTip {
	/// The text of the tooltip
	String text;
	
	/// The component to which this tooltip is associated
	JComponent component;
	
	/// The preferred fixed width of the tooltip
	protected int fixedWidth = 0;
	
	public JMultiLineToolTip() {
		updateUI();
	}
	
	/**
	 * Returns the preferred fixed width of the tooltip.
	 * 
	 * @return  the preferred fixed width of the tooltip or zero if
	 *          there is no preferred width.
	 */
	public int getFixedWidth() {
		return fixedWidth;
	}
	
	/**
	 * Sets the preferred fixed width of the tooltip.
	 * 
	 * @param  width  the new preferred fixed width or zero if you
	 *                don't want to specify a fixed width
	 */
	public void setFixedWidth(int width) {
		this.fixedWidth = width;
	}
	
	public void updateUI() {
		setUI(MultiLineToolTipUI.createUI(this));
	}
}

/**
 * UI class corresponding to JMultiLineToolTip.
 * 
 * Unfortunately I cannot make this class internal to JMultiLineToolTip
 * because of its static members. Meh.
 * 
 * @author tamas
 */
class MultiLineToolTipUI extends BasicToolTipUI {
	/// Shared instance of this UI class
	static MultiLineToolTipUI instance = new MultiLineToolTipUI();
	
	/// The border used by the tooltip
	Border tooltipBorder = new CompoundBorder(
			BorderFactory.createLineBorder(Color.BLACK, 1),
			BorderFactory.createEmptyBorder(2, 2, 2, 2)
	);
	
	JToolTip tip;
	protected CellRendererPane rendererPane;
	
	/// The JTextArea used to render the multi-line tooltip
	private static JTextArea textArea;
	
	/// Returns the shared instance of this UI class
	public static ComponentUI createUI(JComponent c) {
		return instance;
	}
	
	/// Installs this UI to the given component
	public void installUI(JComponent c) {
		super.installUI(c);
		tip = (JToolTip)c;
		rendererPane = new CellRendererPane();
		c.add(rendererPane);
	}
	
	/// Uninstalls this UI from the given component
	public void uninstallUI(JComponent c) {
		super.uninstallUI(c);
		
		c.remove(rendererPane);
		rendererPane = null;
	}
	
	/// Paints the tooltip on the given component using the given graphics context
	public void paint(Graphics g, JComponent c) {
		Dimension size = c.getSize();
		textArea.setBackground(c.getBackground());
		rendererPane.paintComponent(g, textArea, c, 0, 0,
				size.width, size.height, true);
	}
	
	/**
	 * Calculates and returns the preferred size of the tooltip
	 */
	@Override
	public Dimension getPreferredSize(JComponent c) {
		String tipText = ((JToolTip)c).getTipText();
		JMultiLineToolTip comp = (JMultiLineToolTip)c;
		Dimension dim = null;
		
		if (tipText == null)
			return new Dimension(0, 0);
		
		textArea = new JTextArea(tipText);
		textArea.setBorder(tooltipBorder);
		rendererPane.removeAll();
		rendererPane.add(textArea);
		textArea.setWrapStyleWord(true);
		int width = comp.getFixedWidth();
		
		if (width > 0) {
			textArea.setLineWrap(true);
			dim = textArea.getPreferredSize();
			dim.width = width;
			dim.height++;
			textArea.setSize(dim);
		} else
			textArea.setLineWrap(false);
		
		dim = textArea.getPreferredSize();
		dim.height++; dim.width++;
		return dim;
	}
	
	/**
	 * Calculates and returns the minimum size of the tooltip.
	 * 
	 * The minimum size is equal to the preferred size.
	 */
	@Override
	public Dimension getMinimumSize(JComponent c) {
		return getPreferredSize(c);
	}
	
	/**
	 * Calculates and returns the maximum size of the tooltip.
	 * 
	 * The maximum size is equal to the preferred size.
	 */
	@Override
	public Dimension getMaximumSize(JComponent c) {
		return getPreferredSize(c);
	}
}