Functional PostScript Tutorial

Glyphpaths

Glyphpath is a kind of path. It can be transformed and turned into pictures just like all other paths. Glyphpaths are pre-drawn paths that tell us how characters such as "A", "B", "C" etc in a font are be drawn.

Fonts are a set of glyph paths of a specified size. Courier, Times New Roman, and Helvetica are examples of some common fonts. Each font has four elements: a collection of glyphs, a character map, an integer map, and a transformation matrix. Glyphs are data structures that associate symbolic names (called glyphnames) to a path (called glyphpath). Character and integer maps are data structures that associate characters and integers (such as #\A and 2) to glyphnames. The transformation matrix describes a global transformation on the glyphpaths in this font (you may want to adjust the 'slantedness' of Italics, for example).

To create glyphpahts, we must create a font first:

	(define helv (font "Helvetica" 36))

Once we have the font, we can create some glyphpaths:

	(simple-string->glyphpath helv "Hello, Goldfish!")

You can stroke, fill, transform, and compose this glyphpath just as you would with any other paths. Check out the circle-text program in fps-examples.scm which puts text around a circle (it involves some fairly hairly looking transformations, but it is simply figuring out where to put the glyphpaths).

Related procedures in this section:
font, char->glyphpath, int->glyphpath, glyphname->glyphpath
simple-string->glyph, string->glyph,

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