13.4. Macintosh Fonts.   

Here are fonts types that are used in Macintosh.

PostScript Type 1
PostScript Type 3
QuickDraw GX
It is a new font format that function similar to OS. It is a 16-bit font format.

Macintosh machines commonly use bitmap fonts, and these fonts must always be installed with both type 1 and type 3 PostScript fonts. Besides these, a Macintosh can also use TrueType fonts. The new Macintosh operating system engine has a mechanism for handling screen presentation, called QuickDraw GX (QDGX). It has many advantages over older engines, among them the ability to get ligatures, swashes etc. on the fly. QDGX is also a 16-bit font format that allows for example users in Korea to run their machines in their native tongue as well as write.

Although QDGX is a 16-bit encoding, it is "orthogonal" to Unicode. A TrueType font, GX or otherwise, can be encoded using the Unicode standard, but that isn't necessary. However, a TrueType font, and especially a GX font, can contain glyphs for which there is no unique Unicode encoding, e.g. the 'fi' ligature, or a swash 'a' with a trailing curlicue. TrueType GX fonts, however, contain additional information and structure that allows the QDGX system to properly substitute variant glyphs for certain characters in the text. For the above examples, QDGX will, if requested, look for the sequence 'f' + 'i' and substitute the 'fi' ligature, or look for 'a' at the end of a line and substitute the glyph 'a-trailing curlicue'.

It is really quite charming to see this happen, and it makes the font seem more like a clever, trained circus dog that does tricks than a simple font. The GX fonts begin to show an additional personality beyond the image of the glyphs.

The bidirectional text reordering algorithm defined in Unicode is fully implemented in GX. Also, and most unfortunately, since Unicode is the product of an international committee process there were certain compromises that were made in the design, so there really are Unicode character codes for certain ligatures and contextual forms (e.g. the "Basic Glyphs for Arabic Language" codes starting at U+FE70).

Note, however, that GX does not use these; Arabic contextual processing is done the same way as Roman contextual processing. Indeed, it is this uniformity of approach that is, I believe, one of GX's main strengths.

One of the greatest hopes is that we're going to see a real renaissance of fonts and creativity in font designs. GX finally gets us back to the elegance of calligraphy, with the repeatability and precision of the computer.

QDGX supports full 3X3 transformations (including perspective) on all objects in the graphics system, including text. Anti-aliasing is not included in GX 1.0.

The component of QuickDraw GX that deals with font features like automatic ligature substitution is called the Line Layout Manager (LLM), and LLM features are independent of scaler technology. In other words, a Type 1 font can have all of the LLM features that a TrueType font can have under QuickDraw GX.

In fact, Apple and Adobe will be bundling a GX version of ATM with the QuickDraw GX release along with a Type 1 GX version of Tekton Regular which includes lots of additional glyphs and supports most of the LLM features. If you are a Macintosh developer, there are beta GX versions of ATM and Tekton that you can play around with on the QuickDraw GX 1.0b1 release that is part of the WWDC CD.