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\usemodule[present-lines]
\definecolor[maincolor][r=.4,g=.4]
\startdocument[title=Font features,subtitle={\CONTEXT\ 2017 Maibach}]
\startchapter[title=What are they]
\startitemize
\startitem
built in substitution that is often optional like ligatures but for some
languages mandate
\stopitem
\startitem
built in positioning that is assumed to be applied like kerning, mark
anchoring cursive
\stopitem
\startitem
external properties like coloring, spacing, fallback combinations
\stopitem
\startitem
engine related tricks like expansion and protrusion
\stopitem
\startitem
tracing options
\stopitem
\startitem
whatever you like \unknown\ so let me know
\stopitem
\blank[2*big]
\startitem
so in \CONTEXT\ we have font features (driven by font) and pseudo
features (driven by additional needs)
\stopitem
\stopitemize
\stopchapter
\startchapter[title=Substitution]
\startitemize
\startitem
single: replace one by another
\stopitem
\startitem
alternate: replace one by one of a set
\stopitem
\startitem
multiple: replace one by multiple others
\stopitem
\startitem
ligature: replace multiple by one shape
\stopitem
\blank[2*big]
\startitem
contextual lookups and replacements with look back and look ahead
\stopitem
\stopitemize
\stopchapter
\startchapter[title=Positioning]
\startitemize
\startitem
single: repositioning a glyph (with optional marks), this includes
traditional kerning
\stopitem
\startitem
pairwise: repositioning two adjacent glyphs (with optional marks)
\stopitem
\startitem
anchoring: often used for marks to base glyphs, ligatures and other marks
\stopitem
\startitem
attachment: often used for cursive scripts, pasting glyphs in a word together
\stopitem
\blank[2*big]
\startitem
contextual lookups and positioning with look back and look ahead
\stopitem
\stopitemize
\stopchapter
\startchapter[title=Related]
\startitemize
\startitem
analyze: needed for dealing with features that need information about
initial, medial, final and isolated properties
\stopitem
\startitem
reordering: needed for script like devanagari
\stopitem
\startitem
spacing: deals with for positioning glyphs and spaces
\stopitem
\stopitemize
\stopchapter
\startchapter[title=Pitfalls]
\startitemize
\startitem
solutions for similar tasks can be quite different which makes tracing
or checking sometimes hard (many ways to make ligatures)
\stopitem
\startitem
order matters and demands careful font design but it is hard to predict
all cases
\stopitem
\startitem
a sloppy font design can result in a performance hit or huge fonts
\stopitem
\startitem
features can be bugged and fonts vendors seldom have an update policy
\stopitem
\startitem
shapers can differ due to assumptions, heuristics, interpreting
specifications, bugs, \unknown
\stopitem
\stopitemize
\stopchapter
\startchapter[title=Examples]
\startitem
all kind of substitutions: \type {2017-features-substitutiontest.tex}
\stopitem
\startitem
simple inter character kerns: \type {2017-features-kerntest.tex}
\stopitem
\startitem
single character positioning: \type {2017-features-singletest.tex}
\stopitem
\startitem
pairwise character positioning: \type {2017-features-pairtest.tex}
\stopitem
\startitem
contextual positioning: \type {2017-features-contexttest.tex}
\stopitem
\startitem
kerning with space (glue): \type {2017-features-spacetest.tex}
\stopitem
\startitemize
\stopitemize
\stopchapter
\stopdocument
|
