How to use kerning pairs extracted from a TTF file to correctly show glyphs as Path2D in Java?

Question

This question is about recovering glyph font information in Java and it is related to a question posted here. For more details please check the question and ans

Answer 1

GNU Classpath contains an example, gnu.classpath.examples.awt.HintingDemo.java, that may help to solve this problem. This example allows you to visualize glyphs. It reads the font and interprets the language for hints given in it. You can choose to show with hints or without them (hinted glyphs are good for small font sizes but not recommended in large sizes). If you are not used to Truetype hints you will understand with this demo that they align the paths within integer boundaries. The program isn't very fancy but it has all the necessary tools to read the glyphs and interpret the hints with the advantage of visualizing the results.

You don't need the whole package to compile and run this demo. If you are using Eclipse it is easy to create a project for it. First create the packages gnu.classpath.examples.awt and import HintingDemo.java in it. Then you just import all its dependencies, file by file or whole packages at a time. For example, you can import the whole package gnu.java.awt.font and erase OpenTypeFontPeer.java (the demo doesn't need it and it causes an error if you leave it).

This gives a standalone way to read and display glyphs directly from the font file. Interestingly, it doesn't use any kerning information. This has to be added with Apache FOP library. If reading the file twice is a problem you will need a workaround, either going deeply into GNU Classpath to get the same information, or trying to make Apache FOP "to talk" with GNU Classpath. At this time I am unable to say how difficult this is. I am using it only as tools to copy the information and using it elsewhere, not as a way to really read font files in an actual program. Fonts are very compact but are not the most efficient way to display text, especially where there is interpretation of the font language as in the case of Type 1 and Truetype fonts. Getting rid of this interpretation looks like a good idea if you are willing high quality and speed.