Dear gang,
For \addfeature and the like, a virtual font feature defined in terms of a CLD
local function behaves differently from other font features. MWE:
==============
\startluacode
local function squeeze(tfmdata)
for k, v in next, tfmdata.characters do
v.width = 1.75 * (v.height or 0)
v.depth = 1.75 * (v.depth or 0)
end
end
local specification = {
name = "sqtfm",
description = "test",
manipulators = {
base = squeeze,
node = squeeze,
}
}
fonts.handlers.otf.features.register(specification)
\stopluacode
\definefontfeature[forceno]
[mode=node,
script=latn]
\definefontfeature[forceyes]
[mode=node,
script=latn,
smcp=force,
sqtfm=force]
% smcp=yes,
% sqtfm=yes]
\showglyphs
\startTEXpage[offset=1em]
\definedfont[texgyretermes-regular*forceyes]
% \definedfont[texgyretermes-regular*forceno]
% \addfeature{forceyes}
abcdefg
\stopTEXpage
==============
You may toggle these lines:
\definedfont[texgyretermes-regular*forceyes]
% \definedfont[texgyretermes-regular*forceno]
% \addfeature{forceyes}
With
\definedfont[texgyretermes-regular*forceyes]
active we get the expected result: small caps plus some negative squeeze (=
spread in this case).
With
\definedfont[texgyretermes-regular*forceno]
\addfeature{forceyes}
active we get an *unexpected* result: small caps but no negative squeeze.
(Similar results occur if we toggle the "=force" lines with the "=yes" lines,
but the larger project of which this is the MWE uses the force key.)
Clue: A CLD with a feature defined via fonts.handlers.otf.addfeature doesn't
seem to have this problem:
==============
\startluacode
local function squeeze(tfmdata)
for k, v in next, tfmdata.characters do
v.width = 1.75 * (v.height or 0)
v.depth = 1.75 * (v.depth or 0)
end
end
local specification = {
name = "sqtfm",
description = "test",
manipulators = {
base = squeeze,
node = squeeze,
}
}
fonts.handlers.otf.features.register(specification)
fonts.handlers.otf.addfeature {
name = "stest",
type = "substitution",
data = {
a = "X",
b = "P",
}
}
\stopluacode
\definefontfeature[forceno]
[mode=node,
script=latn]
\definefontfeature[forceyes]
[mode=node,
script=latn,
% % smcp=force,
sqtfm=force,
stest=force]
% % smcp=yes,
% sqtfm=yes,
% stest=yes]
\showglyphs
\startTEXpage[offset=1em]
\definedfont[texgyretermes-regular*forceyes]
% \definedfont[texgyretermes-regular*forceno]
% \addfeature{forceyes}
abcdefg
\stopTEXpage
==============
So only the local-function feature appears to exhibit this inconsistency.
What is the explanation for this inconsistent behavior?
Is there a way to get the expected result for \addfeature etc.?
Thank you in advance.
Best wishes
Idris
--
Professor Idris Samawi Hamid
Department of Philosophy
Colorado State University
Fort Collins, CO 80523
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