how do you *actually* find the ascent of a letter? not getAscent, that's for sure

TextFixture.java

import java.awt.Color;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.font.GlyphVector;
import java.awt.geom.Rectangle2D;
import java.util.Arrays;
import java.util.List;

import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.SwingUtilities;

class AscentNoLeadingTextMeasurer implements TextMeasurer {

    @Override
    public int getHeight(Graphics2D g2d, String text) {
        return g2d.getFontMetrics().getAscent()
                - g2d.getFontMetrics().getLeading();
    }

}

class AscentTextMeasurer implements TextMeasurer {

    @Override
    public int getHeight(Graphics2D g2d, String text) {
        return g2d.getFontMetrics().getAscent();
    }

}

class GlyphTextMeasurer implements TextMeasurer {

    @Override
    public int getHeight(Graphics2D g2d, String text) {
        final GlyphVector gv = g2d.getFont()
                .createGlyphVector(g2d.getFontRenderContext(), text);
        return (int) gv.getVisualBounds().getHeight();
    }

}

class HeightTextMeasurer implements TextMeasurer {

    @Override
    public int getHeight(Graphics2D g2d, String text) {
        return g2d.getFontMetrics().getHeight();
    }

}

class LineTextMeasurer implements TextMeasurer {

    @Override
    public int getHeight(Graphics2D g2d, String text) {
        return (int) g2d.getFont()
                .getLineMetrics(text, g2d.getFontRenderContext()).getHeight();
    }

}

class PixelBoundsTextMeasurer implements TextMeasurer {

    @Override
    public int getHeight(Graphics2D g2d, String text) {
        final GlyphVector gv = g2d.getFont()
                .createGlyphVector(g2d.getFontRenderContext(), text);
        return -gv.getPixelBounds(g2d.getFontRenderContext(), 0, 0).y;
    }

}

public class TextFixture extends JFrame {

    private static class TextMeasurerView extends JComponent {
        private final TextMeasurer measurer;

        {
            setPreferredSize(new Dimension(40, 60));
        }

        public TextMeasurerView(TextMeasurer measurer) {
            super();
            this.measurer = measurer;
        }

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            Graphics2D g2d = (Graphics2D) g;
            g2d.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING,
                    RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
            g2d.setFont(new Font(Font.SANS_SERIF, Font.PLAIN, 36));
            final String text = "J";
            final int height = measurer.getHeight(g2d, text);
            final int width = g2d.getFontMetrics().stringWidth(text);
            final int cx = (getWidth() - width) / 2;
            final int cy = getHeight() * 4 / 5;
            final Rectangle2D bounds = new Rectangle2D.Double(cx, cy - height,
                    width, height);
            g2d.setColor(Color.BLUE);
            g2d.draw(bounds);
            g2d.setColor(Color.BLACK);
            g2d.drawString(text, cx, cy);
        }
    }

    public static List<TextMeasurer> measurers = Arrays.asList(
            new HeightTextMeasurer(), new LineTextMeasurer(),
            new AscentTextMeasurer(), new AscentNoLeadingTextMeasurer(),
            new GlyphTextMeasurer(), new PixelBoundsTextMeasurer());

    public static void main(String[] args) {
        SwingUtilities.invokeLater(() -> {
            final TextFixture tf = new TextFixture();
            tf.pack();
            tf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            tf.setLocationRelativeTo(null);
            tf.setVisible(true);
        });
    }

    public TextFixture() {
        super("Text Fixture");
        setLayout(new FlowLayout());
        for (TextMeasurer measurer : measurers) {
            add(new TextMeasurerView(measurer));
        }
    }

}

interface TextMeasurer {
    public int getHeight(Graphics2D g2d, String text);
}