Swing Hacks

Load New Fonts at Runtime #61

Chapter 8, Rendering

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307

HACK

These are all JComponents, but they’re notably lacking the “J”

that starts the name of typical Swing components (

Tree.font

for JTree, TextArea.font for JTextArea, etc.).

Now that you know the keys for the UIDefaults table, instead of blindly

changing all of them to the same font, you can customize a look by applying

different fonts—or different sizes and styles of one or two base fonts—to

different widgets.

H A C K

#61

Load New Fonts at Runtime Hack #61

Who cares what fonts your users have? Bundle the fonts you want your

application to use and load those fonts dynamically!

Using fonts with any predictability used to be a nightmare in Java. For a

while, you could only depend on having access to one serif, one sans-serif,

and one monospaced font, and the constants you’d use to get those fonts

changed between Java 1.0 and 1.1. Fortunately, you’re now free to use any

font installed on the user’s machine and load it by name.

Of course, not everyone has the same fonts. Even different installations of

the same operating system will have different fonts available. I still use some

TrueType fonts I’ve been toting from machine to machine for 15 years, and

it’s a safe bet that very few other people will have those same fonts.

This would seem to limit your Swing application to using only the fonts you

know are installed with an operating system—maybe Arial and Times New

Roman on Windows, Lucida Grande and Palatino on Mac OS X, etc. But it’s

not so. You can load font files at runtime and make them available to your

Java application, even if the font isn’t installed on the user’s machine.

The Wonders of createFont( )

Using dynamically loaded fonts comes down to a single, critical, often over-

looked AWT method in the

Font class: createFont( ). This method, intro-

duced in Java 1.3, takes two parameters: a font format (as an

int), which to

date has no legal value other than

Font.TRUETYPE_FONT, and an InputStream.

This stream is typically a

FileInputStream from a .ttf TrueType file, or some

equivalent. By equivalent, I meant that you could presumably put the font

on the network and get a stream from a

URL or put the font file inside a .jar,

find it along the classpath with

ClassLoader.getResourceAsStream( ), and

load from that.