I'm assuming that you receive the error when calling loadFont(), createFont(), or some other function that returns a PFont... perhaps simply casting to a NewFont will be sufficient, i.e.:

1. NewFont font = (NewFont) createFont("Arial", 9, true);

I get a cannot be cast exception.  Was hoping someone might be able to post a tiny example of a class that extends PFont in this way.

Looks like I may need to duplicate the createFont() methods and have them return the extended class.  Then I should be able to pass the new class into places that accept PFont.  At least, that's what I thinking.

Duplicating the createFont is probably the easier way to do it. You only need to duplicate one of these methods since all the others  call it. You will also need a suitable constructor in the NewFont clso it is not an inner class of the sketch.

The following code works all you need to do is add appropriate methods to NewFont


Sketch tab

1. import java.awt.*;
2. NewFont nfont;
3. 
   
4. void setup() {
5.   size(300, 300);
6.   nfont =(NewFont) createFont("Times New Roman", 20);
7.   textFont(nfont);
8.   background(255);
9.   fill(0);
10.   text("Quarks was here", 20, 50);
11. }
12. 
    
13. public PFont createFont(String name, float size,
14.                             boolean smooth, char charset[]) {
15.   String lowerName = name.toLowerCase();
16.   Font baseFont = null;
17.   try {
18.     InputStream stream = null;
19.     if (lowerName.endsWith(".otf") || lowerName.endsWith(".ttf")) {
20.       stream = createInput(name);
21.       if (stream == null) {
22.         System.err.println("The font \"" + name + "\" " +
23.           "is missing or inaccessible, make sure " +
24.           "the URL is valid or that the file has been " +
25.           "added to your sketch and is readable.");
26.         return null;
27.       }
28.       baseFont = Font.createFont(Font.TRUETYPE_FONT, createInput(name));
29.     }
30.     else {
31.       baseFont = NewFont.findFont(name);
32.     }
33.     return new NewFont(baseFont.deriveFont(size), smooth, charset,
34.     stream != null);
35.   }
36.   catch (Exception e) {
37.     System.err.println("Problem createFont(" + name + ")");
38.     e.printStackTrace();
39.     return null;
40.   }
41. }

The only change I had to make is highlighted.

NewFont.java

1. import processing.core.*;
2. import java.awt.*;
3. 
   
4. public class NewFont extends PFont {
5.  
6.   public NewFont(Font font, boolean smooth, char charset[], boolean stream) {
7.     super(font, smooth, charset);
8.     this.stream = stream;
9.   }
10.  
11. }