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if not modules then modules = { } end modules ['font-imp-spacekerns'] = {
version = 1.001,
comment = "companion to font-ini.mkiv and hand-ini.mkiv",
author = "Hans Hagen, PRAGMA-ADE, Hasselt NL",
copyright = "PRAGMA ADE / ConTeXt Development Team",
license = "see context related readme files"
}
if not context then return end
-- This is an experiment. See font-ots.lua for original implementation.
local type, next = type, next
local insert, setmetatableindex = table.insert, table.setmetatableindex
local fonts = fonts
local otf = fonts.handlers.otf
local fontdata = fonts.hashes.identifiers
local fontfeatures = fonts.hashes.features
local otffeatures = fonts.constructors.features.otf
local registerotffeature = otffeatures.register
local handlers = otf.handlers
local setspacekerns = nodes.injections.setspacekerns
function handlers.trigger_space_kerns(head,dataset,sequence,initialrl,font,attr)
local features = fontfeatures[font]
local enabled = features and features.spacekern
if enabled then
setspacekerns(font,sequence) -- called quite often, each glyphrun
end
return head, enabled
end
local function hasspacekerns(data)
local resources = data.resources
local sequences = resources.sequences
local validgpos = resources.features.gpos
if validgpos and sequences then
for i=1,#sequences do
local sequence = sequences[i]
local steps = sequence.steps
if steps then -- and sequence.features[tag] then
local kind = sequence.type
if kind == "gpos_pair" then -- or kind == "gpos_single" then
for i=1,#steps do
local step = steps[i]
local coverage = step.coverage
local rules = step.rules
-- if rules then
-- -- not now: analyze (simple) rules
-- elseif not coverage then
-- -- nothing to do
-- elseif kind == "gpos_single" then
-- -- maybe a message that we ignore
-- elseif kind == "gpos_pair" then
if coverage and not rules then
local format = step.format
if format == "move" or format == "kern" then
local kerns = coverage[32]
if kerns then
return true
end
for k, v in next, coverage do
if v[32] then
return true
end
end
elseif format == "pair" then
local kerns = coverage[32]
if kerns then
for k, v in next, kerns do
local one = v[1]
if one and one ~= true then
return true
end
end
end
for k, v in next, coverage do
local kern = v[32]
if kern then
local one = kern[1]
if one and one ~= true then
return true
end
end
end
end
end
end
end
end
end
end
return false
end
otf.readers.registerextender {
name = "spacekerns",
action = function(data)
data.properties.hasspacekerns = hasspacekerns(data)
end
}
local function newdata(t,k)
local v = {
left = { },
right = { },
last = 0,
feat = nil,
}
t[k] = v
return v
end
local function spaceinitializer(tfmdata,value) -- attr
local resources = tfmdata.resources
local spacekerns = resources and resources.spacekerns
if value and spacekerns == nil then
local rawdata = tfmdata.shared and tfmdata.shared.rawdata
local properties = rawdata.properties
if properties and properties.hasspacekerns then
local sequences = resources.sequences
local validgpos = resources.features.gpos
if validgpos and sequences then
local data = setmetatableindex(newdata)
for i=1,#sequences do
local sequence = sequences[i]
local steps = sequence.steps
if steps then
-- we don't support space kerns in other features
-- local kern = sequence.features[tag]
-- if kern then
for tag, kern in next, sequence.features do
local d = data[tag]
local left = d.left
local right = d.right
local last = d.last
local feat = d.feat
local kind = sequence.type
if kind == "gpos_pair" then -- or kind == "gpos_single" then
if feat then
for script, languages in next, kern do
local f = feat[script]
if f then
for l in next, languages do
f[l] = true
end
else
feat[script] = languages
end
end
else
feat = kern
d.feat = feat
end
for i=1,#steps do
local step = steps[i]
local coverage = step.coverage
local rules = step.rules
-- if rules then
-- -- not now: analyze (simple) rules
-- elseif not coverage then
-- -- nothing to do
-- elseif kind == "gpos_single" then
-- -- makes no sense in TeX
-- elseif kind == "gpos_pair" then
if coverage and not rules then
local format = step.format
if format == "move" or format == "kern" then
local kerns = coverage[32]
if kerns then
for k, v in next, kerns do
right[k] = v
end
end
for k, v in next, coverage do
local kern = v[32]
if kern then
left[k] = kern
end
end
elseif format == "pair" then
local kerns = coverage[32]
if kerns then
for k, v in next, kerns do
local one = v[1]
if one and one ~= true then
right[k] = one[3]
end
end
end
for k, v in next, coverage do
local kern = v[32]
if kern then
local one = kern[1]
if one and one ~= true then
left[k] = one[3]
end
end
end
end
end
end
last = i
end
d.last = last
end
end
end
for tag, d in next, data do
local left = d.left
local right = d.right
left = next(left) and left or false
right = next(right) and right or false
if left or right then
local last = d.last
local feat = d.feat
if last > 0 then
local triggersequence = {
-- no steps, see (!!)
features = { [tag] = feat or { dflt = { dflt = true, } } },
flags = noflags,
name = "trigger_space_kerns",
order = { tag },
type = "trigger_space_kerns",
left = left,
right = right,
}
insert(sequences,last,triggersequence)
d.last = d.last + 1
spacekerns = true
end
end
end
end
end
if not spacekerns then
spacekerns = false
end
resources.spacekerns = spacekerns
end
return spacekerns
end
registerotffeature {
name = "spacekern",
description = "space kern injection",
default = true,
initializers = {
node = spaceinitializer,
},
}
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