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if not modules then modules = { } end modules ['typo-krn'] = {
version = 1.001,
comment = "companion to typo-krn.mkiv",
author = "Hans Hagen, PRAGMA-ADE, Hasselt NL",
copyright = "PRAGMA ADE / ConTeXt Development Team",
license = "see context related readme files"
}
local next, type, tonumber = next, type, tonumber
local utfchar = utf.char
local nodes, node, fonts = nodes, node, fonts
local find_node_tail = node.tail or node.slide
local free_node = node.free
local free_nodelist = node.flush_list
local copy_node = node.copy
local copy_nodelist = node.copy_list
local insert_node_before = node.insert_before
local insert_node_after = node.insert_after
local end_of_math = node.end_of_math
local texattribute = tex.attribute
local unsetvalue = attributes.unsetvalue
local nodepool = nodes.pool
local tasks = nodes.tasks
local new_gluespec = nodepool.gluespec
local new_kern = nodepool.kern
local new_glue = nodepool.glue
local nodecodes = nodes.nodecodes
local kerncodes = nodes.kerncodes
local skipcodes = nodes.skipcodes
local glyph_code = nodecodes.glyph
local kern_code = nodecodes.kern
local disc_code = nodecodes.disc
local glue_code = nodecodes.glue
local hlist_code = nodecodes.hlist
local vlist_code = nodecodes.vlist
local math_code = nodecodes.math
local kerning_code = kerncodes.kerning
local userkern_code = kerncodes.userkern
local userskip_code = skipcodes.userskip
local spaceskip_code = skipcodes.spaceskip
local xspaceskip_code = skipcodes.xspaceskip
local fonthashes = fonts.hashes
local fontdata = fonthashes.identifiers
local chardata = fonthashes.characters
local quaddata = fonthashes.quads
local markdata = fonthashes.marks
local v_max = interfaces.variables.max
typesetters = typesetters or { }
local typesetters = typesetters
typesetters.kerns = typesetters.kerns or { }
local kerns = typesetters.kerns
kerns.mapping = kerns.mapping or { }
kerns.factors = kerns.factors or { }
local a_kerns = attributes.private("kern")
local a_fontkern = attributes.private('fontkern')
kerns.attribute = kerns.attribute
storage.register("typesetters/kerns/mapping", kerns.mapping, "typesetters.kerns.mapping")
storage.register("typesetters/kerns/factors", kerns.factors, "typesetters.kerns.factors")
local mapping = kerns.mapping
local factors = kerns.factors
-- one must use liga=no and mode=base and kern=yes
-- use more helpers
-- make sure it runs after all others
-- there will be a width adaptor field in nodes so this will change
-- todo: interchar kerns / disc nodes / can be made faster
local gluefactor = 4 -- assumes quad = .5 enspace
kerns.keepligature = false -- just for fun (todo: control setting with key/value)
kerns.keeptogether = false -- just for fun (todo: control setting with key/value)
-- can be optimized .. the prev thing .. but hardly worth the effort
local function kern_injector(fillup,kern)
if fillup then
local g = new_glue(kern)
local s = g.spec
s.stretch = kern
s.stretch_order = 1
return g
else
return new_kern(kern)
end
end
local function spec_injector(fillup,width,stretch,shrink)
if fillup then
local s = new_gluespec(width,2*stretch,2*shrink)
s.stretch_order = 1
return s
else
return new_gluespec(width,stretch,shrink)
end
end
-- needs checking ... base mode / node mode
local function do_process(namespace,attribute,head,force) -- todo: glue so that we can fully stretch
local start, done, lastfont = head, false, nil
local keepligature = kerns.keepligature
local keeptogether = kerns.keeptogether
local fillup = false
while start do
-- faster to test for attr first
local attr = force or start[attribute]
if attr and attr > 0 then
start[attribute] = unsetvalue
local krn = mapping[attr]
if krn == v_max then
krn = .25
fillup = true
else
fillup = false
end
if krn and krn ~= 0 then
local id = start.id
if id == glyph_code then
lastfont = start.font
local c = start.components
if c then
if keepligature and keepligature(start) then
-- keep 'm
else
c = do_process(namespace,attribute,c,attr)
local s = start
local p, n = s.prev, s.next
local tail = find_node_tail(c)
if p then
p.next = c
c.prev = p
else
head = c
end
if n then
n.prev = tail
end
tail.next = n
start = c
s.components = nil
-- we now leak nodes !
-- free_node(s)
done = true
end
end
local prev = start.prev
if not prev then
-- skip
elseif markdata[lastfont][start.char] then
-- skip
else
local pid = prev.id
if not pid then
-- nothing
elseif pid == kern_code then
if prev.subtype == kerning_code or prev[a_fontkern] then
if keeptogether and prev.prev.id == glyph_code and keeptogether(prev.prev,start) then -- we could also pass start
-- keep 'm
else
-- not yet ok, as injected kerns can be overlays (from node-inj.lua)
prev.subtype = userkern_code
prev.kern = prev.kern + quaddata[lastfont]*krn -- here
done = true
end
end
elseif pid == glyph_code then
if prev.font == lastfont then
local prevchar, lastchar = prev.char, start.char
if keeptogether and keeptogether(prev,start) then
-- keep 'm
else
local kerns = chardata[lastfont][prevchar].kerns
local kern = kerns and kerns[lastchar] or 0
krn = kern + quaddata[lastfont]*krn -- here
insert_node_before(head,start,kern_injector(fillup,krn))
done = true
end
else
krn = quaddata[lastfont]*krn -- here
insert_node_before(head,start,kern_injector(fillup,krn))
done = true
end
elseif pid == disc_code then
-- a bit too complicated, we can best not copy and just calculate
-- but we could have multiple glyphs involved so ...
local disc = prev -- disc
local pre, post, replace = disc.pre, disc.post, disc.replace
local prv, nxt = disc.prev, disc.next
if pre and prv then -- must pair with start.prev
-- this one happens in most cases
local before = copy_node(prv)
pre.prev = before
before.next = pre
before.prev = nil
pre = do_process(namespace,attribute,before,attr)
pre = pre.next
pre.prev = nil
disc.pre = pre
free_node(before)
end
if post and nxt then -- must pair with start
local after = copy_node(nxt)
local tail = find_node_tail(post)
tail.next = after
after.prev = tail
after.next = nil
post = do_process(namespace,attribute,post,attr)
tail.next = nil
disc.post = post
free_node(after)
end
if replace and prv and nxt then -- must pair with start and start.prev
local before = copy_node(prv)
local after = copy_node(nxt)
local tail = find_node_tail(replace)
replace.prev = before
before.next = replace
before.prev = nil
tail.next = after
after.prev = tail
after.next = nil
replace = do_process(namespace,attribute,before,attr)
replace = replace.next
replace.prev = nil
after.prev.next = nil
disc.replace = replace
free_node(after)
free_node(before)
else
if prv and prv.id == glyph_code and prv.font == lastfont then
local prevchar, lastchar = prv.char, start.char
local kerns = chardata[lastfont][prevchar].kerns
local kern = kerns and kerns[lastchar] or 0
krn = kern + quaddata[lastfont]*krn -- here
else
krn = quaddata[lastfont]*krn -- here
end
disc.replace = kern_injector(false,krn) -- only kerns permitted, no glue
end
end
end
elseif id == glue_code then
local subtype = start.subtype
if subtype == userskip_code or subtype == xspaceskip_code or subtype == spaceskip_code then
local s = start.spec
local w = s.width
if w > 0 then
local width, stretch, shrink = w+gluefactor*w*krn, s.stretch, s.shrink
start.spec = spec_injector(fillup,width,stretch*width/w,shrink*width/w)
done = true
end
end
elseif id == kern_code then
-- if start.subtype == kerning_code then -- handle with glyphs
-- local sk = start.kern
-- if sk > 0 then
-- start.kern = sk*krn
-- done = true
-- end
-- end
elseif lastfont and (id == hlist_code or id == vlist_code) then -- todo: lookahead
local p = start.prev
if p and p.id ~= glue_code then
insert_node_before(head,start,kern_injector(fillup,quaddata[lastfont]*krn))
done = true
end
local n = start.next
if n and n.id ~= glue_code then
insert_node_after(head,start,kern_injector(fillup,quaddata[lastfont]*krn))
done = true
end
elseif id == math_code then
start = end_of_math(start)
end
end
end
if start then
start = start.next
end
end
return head, done
end
local enabled = false
function kerns.set(factor)
if factor ~= v_max then
factor = tonumber(factor) or 0
end
if factor == v_max or factor ~= 0 then
if not enabled then
tasks.enableaction("processors","typesetters.kerns.handler")
enabled = true
end
local a = factors[factor]
if not a then
a = #mapping + 1
factors[factors], mapping[a] = a, factor
end
factor = a
else
factor = unsetvalue
end
texattribute[a_kerns] = factor
return factor
end
local function process(namespace,attribute,head)
return do_process(namespace,attribute,head) -- no direct map, because else fourth argument is tail == true
end
kerns.handler = nodes.installattributehandler {
name = "kern",
namespace = kerns,
processor = process,
}
-- interface
commands.setcharacterkerning = kerns.set
|