Is there a non-proprietary equivalent to FontUtilities.getCompositeFontUIResource(Font)?

Question

If you just create your font using new Font("Arial", Font.PLAIN, 10), later, when you try to display missing glyphs in that font, you will get the familiar squares indicating missing glyphs.

A long time ago, we found a workaround for this - pass the font to FontUtilities.getCompositeFontUIResource(Font) and you get back a Font which handles fallback for characters which aren't in the font itself.

Problem is, that utility is in sun.font, and I would like to eliminate the compiler warning.

Given that many years have passed in the meantime, is there now a proper way to do this?

Demo:

import java.awt.Font;
import java.awt.GridLayout;

import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.SwingUtilities;

import sun.font.FontUtilities;

public class TestFonts implements Runnable
{
    @Override
    public void run()
    {
        Font font = new Font("Arial", Font.PLAIN, 20);

        JLabel label1 = new JLabel("Before \u30C6\u30B9\u30C8");
        label1.setFont(font);

        JLabel label2 = new JLabel("After \u30C6\u30B9\u30C8");
        label2.setFont(FontUtilities.getCompositeFontUIResource(font));

        JFrame frame = new JFrame("Font Test");
        frame.setLayout(new GridLayout(2, 1));
        frame.add(label1);
        frame.add(label2);
        frame.pack();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);
    }

    public static void main(String[] args)
    {
        SwingUtilities.invokeLater(new TestFonts());
    }
}

Result:

Possible duplicate of [How do I specify fallback fonts in Java2D/Graphics2D](http://stackoverflow.com/questions/9482255/how-do-i-specify-fallback-fonts-in-java2d-graphics2d) — Mike 'Pomax' Kamermans, Feb 03 '16 at 01:51
Maybe, although the answer in there wouldn't solve the issue for me, because I'm not keen on rewriting every single class in Swing that happens to render text. — Hakanai, Feb 03 '16 at 04:46

score 2 · Answer 1 · answered Feb 10 '16 at 22:18

After digging in the JDK sources a bit, I found a public method which calls the internal method directly. I don't know how dodgy this is considered, but it's at least public API. :)

        label2.setFont(StyleContext.getDefaultStyleContext()
            .getFont(familyName, style, size));

VGR · Answer 2 · 2016-02-10T14:13:19.003

You can exploit the fact that JComponents are able to display HTML, and override the font for characters which the JComponent's font cannot display, by placing those characters in a <span>:

import java.util.Formatter;

import java.awt.Font;
import java.awt.GridLayout;

import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.SwingUtilities;

import sun.font.FontUtilities;

public class TestFonts implements Runnable
{
    /**
     * Replaces plain text meant to be displayed in a JComponent with
     * HTML that forces the font to Dialog for any characters which the
     * specified font cannot natively display.
     *
     * @param originalText text to transform to HTML, with forced fonts
     *                     where needed
     * @param font default font which will be used to display text
     *
     * @return HTML version of original text, which forces fonts where
     *         necessary to ensure all characters will be displayed
     */
    static String toCompositeFontText(String originalText,
                                      Font font) {
        Formatter html = new Formatter();
        html.format("%s", "<html><body style='white-space: nowrap'>");

        boolean fontOverride = false;
        int len = originalText.length();
        for (int i = 0; i < len; i = originalText.offsetByCodePoints(i, 1)) {
            int c = originalText.codePointAt(i);

            if (font.canDisplay(c)) {
                if (fontOverride) {
                    html.format("%s", "</span>");
                    fontOverride = false;
                }
            } else {
                if (!fontOverride) {
                    html.format("<span style='font-family: \"%s\"'>",
                        Font.DIALOG);
                    fontOverride = true;
                }
            }

            if (c == '<' || c == '>' || c == '&' || c < 32 || c >= 127) {
                html.format("&#%d;", c);
            } else {
                html.format("%c", c);
            }
        }

        if (fontOverride) {
            html.format("%s", "</span>");
        }

        html.format("%s", "</body></html>");

        return html.toString();
    }

    /**
     * Replaces text of the specified JLabel with HTML that contains the
     * same text, but forcing the font to Dialog for any characters which
     * the JLabel's current font cannot display.
     *
     * @param label JLabel whose text will be adjusted and replaced
     */
    static void adjustText(JLabel label) {
        label.setText(toCompositeFontText(label.getText(), label.getFont()));
    }

    @Override
    public void run()
    {
        Font font = new Font("Arial", Font.PLAIN, 20);

        JLabel label1 = new JLabel("Before \u30C6\u30B9\u30C8");
        label1.setFont(font);

        JLabel label2 = new JLabel("After \u30C6\u30B9\u30C8");
        label2.setFont(FontUtilities.getCompositeFontUIResource(font));

        JLabel label3 = new JLabel("Corrected \u30C6\u30B9\u30C8");
        label3.setFont(font);
        adjustText(label3);

        JFrame frame = new JFrame("Font Test");
        frame.setLayout(new GridLayout(3, 1));
        frame.add(label1);
        frame.add(label2);
        frame.add(label3);
        frame.pack();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);
    }

    public static void main(String[] args)
    {
        SwingUtilities.invokeLater(new TestFonts());
    }
}

Update:

In addition, you can monitor a label's text property, to make this happen automatically:

label.addPropertyChangeListener("text", new PropertyChangeListener() {
    @Override
    public void propertyChange(PropertyChangeEvent event) {
        String text = (String) event.getNewValue();
        if (text != null && !text.startsWith("<html>")) {
            adjustText((JLabel) event.getSource());
        }
    }
});

The obvious drawback is that there is no (easy) way to adjust text which already starts with <html>. (Actually I'm fairly sure even that could be done by loading the label's text as an HTMLDocument.)

I don't really want to have to do this on any component that might contain some variable text... :/ — Hakanai, Feb 10 '16 at 03:32
I agree it's awkward. You could add a PropertyChangeListener to make it an automatic process. Answer updated accordingly. — VGR, Feb 10 '16 at 14:14

Is there a non-proprietary equivalent to FontUtilities.getCompositeFontUIResource(Font)?

2 Answers2