Java Code:
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.font.FontRenderContext;
import java.awt.font.LineMetrics;
import java.awt.geom.Line2D;

import javax.swing.JFrame;
import javax.swing.JPanel;

public class LineMetricsIllustration extends JPanel{
  public void paint(Graphics g) {
    Graphics2D g2 = (Graphics2D) g;

    g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
        RenderingHints.VALUE_ANTIALIAS_ON);
    Font font = new Font("Serif", Font.PLAIN, 72);
    g2.setFont(font);

    String s = "Java Source and Support";
    float x = 50, y = 150;

    // Draw the baseline.
    FontRenderContext frc = g2.getFontRenderContext();
    float width = (float) font.getStringBounds(s, frc).getWidth();
    Line2D baseline = new Line2D.Float(x, y, x + width, y);
    g2.setPaint(Color.red);
    g2.draw(baseline);

    // Draw the ascent.
    LineMetrics lm = font.getLineMetrics(s, frc);
    Line2D ascent = new Line2D.Float(x, y - lm.getAscent(), x + width, y
        - lm.getAscent());
    g2.draw(ascent);

    // Draw the descent.
    Line2D descent = new Line2D.Float(x, y + lm.getDescent(), x + width, y
        + lm.getDescent());
    g2.draw(descent);

    // Draw the leading.
    Line2D leading = new Line2D.Float(x, y + lm.getDescent()
        + lm.getLeading(), x + width, y + lm.getDescent()
        + lm.getLeading());
    g2.draw(leading);

    // Render the string.
    g2.setPaint(Color.black);
    g2.drawString(s, x, y);
  }

  public static void main(String[] args) {
    JFrame f = new JFrame();
    f.getContentPane().add(new LineMetricsIllustration());
    f.setSize(850, 250);
    f.show();
  }
}