Hagen - Pragma ADE

the list and relate characters to a smallcaps shape. A slightly more complex feature
might also demand some positioning. One step further is the use of contextual analysis,
i.e. looking at previous, current and following characters (or glyphs). Because features
can range from simple to complex the actual processing is not per feature! A font comes
with a sequence of so called lookups that relate to a feature, script and language. Also,
each feature can use one--to--one, multiple--to--one and many--to--many replacements as
well as relative positioning.
So, what actually happens is not that a feature is processed, but that all features are
dealt with at the same time, in the order that the font prescribes. Enabling a specific
feature means that a step is executed, while a disabled feature skips all steps that are
tagged as belonging to that feature. And, as each feature can use contextual analysis,
you can imagine that the effective sequence of actions can be a complex mix.
We need a proper example here, probably something arabic.
5.3 Extras
Todo.
5.4 Goodies
Goodies range from simple to complex. They share that they are defined in files and
loaded at runtime. There is a good change that when you read this, that there are already
more goodies than mentioned here. Here we will just mention a couple of goodies. More
details can be found in the files that ship with ConT E Xt and have suffix lfg.
A goodie file is a regular Lua file and is supposed to return a table. This table collects
data that is used for implementing the goodie or relates to a regular feature. It can also
provide information that is used for patching a font. An example of a simple goodie file
is the ones that accompanies the first release of the OpenType Lucida fonts.
return {
name = "lucida-opentype-math",
version = "1.00",
comment = "Goodies that complement lucida opentype.",
author = "Hans Hagen",
copyright = "ConTeXt development team",
mathematics = {
alternates = {
italic = {
feature = 'ss01',
value = 1,
comment = "Mathematical Alternative Italic"
},
}
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Features