Multi-line tooltips in Java?

Question

I\'m trying to display tooltips in Java which may or may not be paragraph-length. How can I word-wrap long tooltips?

Answer 1

Here is a version which I have used before, it works well if you are loading your tool tips from ResourceBundles:

import javax.swing.JComponent;
import javax.swing.JToolTip;
import javax.swing.LookAndFeel;
import javax.swing.UIManager;
import javax.swing.plaf.ComponentUI;
import javax.swing.plaf.ToolTipUI;
import java.awt.Dimension;
import java.awt.FontMetrics;
import java.awt.Graphics;
import java.util.regex.Pattern;

/**
 * A tooltip that wraps multi-line text.
 */
public final class MultiLineToolTipUI extends ToolTipUI {

    private static final int INSET = 2;

    private static final Pattern LINE_SPLITTER = Pattern.compile("$", Pattern.MULTILINE);

    private static final MultiLineToolTipUI SHARED_INSTANCE = new MultiLineToolTipUI();

    /**
     * Install the multi-line tooltip into the UI manager.
     */
    public static void installUI() {
        String toolTipUI = MultiLineToolTipUI.class.getName();
        UIManager.put("ToolTipUI", toolTipUI);
        UIManager.put(toolTipUI, MultiLineToolTipUI.class);
    }

    @SuppressWarnings("UnusedDeclaration")
    public static ComponentUI createUI(JComponent c) {
        return SHARED_INSTANCE;
    }

    private MultiLineToolTipUI() {}

    @Override
    public Dimension getMaximumSize(JComponent c) {
        return getPreferredSize(c);
    }

    @Override
    public Dimension getMinimumSize(JComponent c) {
        return getPreferredSize(c);
    }

    @Override
    public Dimension getPreferredSize(JComponent c) {
        String[] lines = LINE_SPLITTER.split(((JToolTip) c).getTipText());
        if (lines.length == 0) {
            return new Dimension(2 * INSET, 2 * INSET);
        }
        FontMetrics metrics = c.getFontMetrics(c.getFont());
        Graphics g = c.getGraphics();
        int w = 0;
        for (String line : lines) {
            w = Math.max(w, (int) metrics.getStringBounds(line, g).getWidth());
        }
        int h = lines.length * metrics.getHeight();
        return new Dimension(w + 2 * INSET, h + 2 * INSET);
    }

    @Override
    public void installUI(JComponent c) {
        LookAndFeel.installColorsAndFont(c, "ToolTip.background", "ToolTip.foreground", "ToolTip.font");
        LookAndFeel.installBorder(c, "ToolTip.border");
    }

    @Override
    public void paint(Graphics g, JComponent c) {
        int w = c.getWidth(), h = c.getHeight();
        g.setColor(c.getBackground());
        g.fillRect(0, 0, w, h);
        g.setColor(c.getForeground());
        g.drawRect(0, 0, w, h);
        String[] lines = LINE_SPLITTER.split(((JToolTip) c).getTipText());
        if (lines.length != 0) {
            FontMetrics metrics = c.getFontMetrics(c.getFont());
            int height = metrics.getHeight();
            int y = INSET + metrics.getAscent();
            for (String line : lines) {
                g.drawString(line, INSET, y);
                y += height;
            }
        }
    }

    @Override
    public void uninstallUI(JComponent c) {
        LookAndFeel.uninstallBorder(c);
    }

}

And you would use it by calling this method, before your UI is created:

MultiLineToolTipUI.installUI();

Then in your properties files just insert newlines to wrap your tool tips as desired.