if not modules then modules = { } end modules ['letterspace'] = {
version = "2.8",
comment = "companion to luaotfload-main.lua",
author = "Hans Hagen, PRAGMA-ADE, Hasselt NL; adapted by Philipp Gesang",
copyright = "PRAGMA ADE / ConTeXt Development Team",
license = "see context related readme files"
}
--- This code diverged quite a bit from its origin in Context. Please
--- do *not* report bugs on the Context list.
local log = luaotfload.log
local logreport = log.report
-- UF
texio.write_nl ("------------------")
texio.write_nl ("!!!!! UF: Using CHANGED luaotfload-letterspace 2017-07-14 !!!!!")
texio.write_nl ("------------------")
-- /UF
local getmetatable = getmetatable
local require = require
local setmetatable = setmetatable
local tonumber = tonumber
local next = next
local nodes, node, fonts = nodes, node, fonts
local nodedirect = nodes.nuts
local getfield = nodedirect.getfield
local setfield = nodedirect.setfield
local field_setter = function (name) return function (n, ...) setfield (n, name, ...) end end
local field_getter = function (name) return function (n, ...) getfield (n, name, ...) end end
local getfont = nodedirect.getfont
local getid = nodedirect.getid
local getnext = nodedirect.getnext or field_getter "next"
local setnext = nodedirect.setnext or field_setter "next"
local getprev = nodedirect.getprev or field_getter "prev"
local setprev = nodedirect.setprev or field_setter "prev"
--- since r5336
local getboth = nodedirect.getboth or function (n)
return getprev (n), getnext (n)
end
local setlink = nodedirect.setlink or function (a, b)
setnext (a, b)
setprev (b, a)
end
local getdisc = nodedirect.getdisc or field_getter "disc"
local setdisc = nodedirect.setdisc or field_setter "disc"
local getsubtype = nodedirect.getsubtype or field_getter "subtype"
local setsubtype = nodedirect.setsubtype or field_setter "subtype"
local getchar = nodedirect.getchar or field_getter "subtype"
local setchar = nodedirect.setchar or field_setter "subtype"
local find_node_tail = nodedirect.tail
local todirect = nodedirect.tonut
local tonode = nodedirect.tonode
local insert_node_before = nodedirect.insert_before
local free_node = nodedirect.free -- may cause double free
local free_node = function (n)
logreport ("term", 5, "letterspace", "not calling free_node(%d)", n)
-- free_node (n)
end
local copy_node = nodedirect.copy
local new_node = nodedirect.new
local nodepool = nodedirect.pool
-- local new_kern = nodepool.kern -- UF removed 2017-07-14
local nodecodes = nodes.nodecodes
local glyph_code = nodecodes.glyph
local kern_code = nodecodes.kern
local disc_code = nodecodes.disc
local math_code = nodecodes.math
local glue_code = nodecodes.glue
local fonthashes = fonts.hashes
local chardata = fonthashes.characters
local quaddata = fonthashes.quads
local otffeatures = fonts.constructors.newfeatures "otf"
--[[doc--
Since the letterspacing method was derived initially from Context’s
typo-krn.lua we keep the sub-namespace “letterspace” inside the
“luaotfload” table.
--doc]]--
luaotfload.letterspace = luaotfload.letterspace or { }
local letterspace = luaotfload.letterspace
letterspace.keepligature = false
letterspace.keeptogether = false
---=================================================================---
--- preliminary definitions
---=================================================================---
-- We set up a layer emulating some Context internals that are needed
-- for the letterspacing callback.
-----------------------------------------------------------------------
--- node-ini
-----------------------------------------------------------------------
local bothways = function (t) return table.swapped (t, t) end
local kerncodes = bothways { [0] = "fontkern"
, [1] = "userkern"
, [2] = "accentkern"
}
local skipcodes = bothways { [0] = "userskip"
, [13] = "spaceskip"
, [14] = "xspaceskip"
}
kerncodes.kerning = kerncodes.fontkern --- idiosyncrasy
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
-----------------------------------------------------------------------
--- node-res
-----------------------------------------------------------------------
local glue_spec = new_node "glue_spec"
local new_gluespec = function (width,
stretch, shrink,
stretch_order, shrink_order)
local spec = copy_node(glue_spec)
if width then setfield(spec, "width" , width ) end
if stretch then setfield(spec, "stretch" , stretch ) end
if shrink then setfield(spec, "shrink" , shrink ) end
if stretch_order then setfield(spec, "stretch_order", stretch_order) end
if shrink_order then setfield(spec, "shrink_order" , shrink_order ) end
return spec
end
local new_glue = function (width, stretch, shrink,
stretch_order, shrink_order)
local n = new_node "glue"
if not width then return n end
-- no spec
if width == false then
local width = tonumber(width)
if width then
setfield(n, "spec",
new_gluespec(width, stretch, shrink,
stretch_order, shrink_order))
end
else
-- shared
setfield(n, "spec", copy_node(width))
end
return n
end
-----------------------------------------------------------------------
--- font-hsh
-----------------------------------------------------------------------
--- some initialization resembling font-hsh
local fonthashes = fonts.hashes
local identifiers = fonthashes.identifiers --- was: fontdata
local chardata = fonthashes.characters
local quaddata = fonthashes.quads
local parameters = fonthashes.parameters
--- ('a, 'a) hash -> (('a, 'a) hash -> 'a -> 'a) -> ('a, 'a) hash
local setmetatableindex = function (t, f)
local mt = getmetatable(t)
if mt then
mt.__index = f
else
setmetatable(t, { __index = f })
end
return t
end
if not parameters then
parameters = { }
setmetatableindex(parameters, function(t, k)
if k == true then
return parameters[currentfont()]
else
local parameters = identifiers[k].parameters
t[k] = parameters
return parameters
end
end)
--fonthashes.parameters = parameters
end
if not chardata then
chardata = { }
setmetatableindex(chardata, function(t, k)
if k == true then
return chardata[currentfont()]
else
local tfmdata = identifiers[k]
if not tfmdata then --- unsafe
tfmdata = font.fonts[k]
end
if tfmdata then
local characters = tfmdata.characters
t[k] = characters
return characters
end
end
end)
fonthashes.characters = chardata
end
if not quaddata then
quaddata = { }
setmetatableindex(quaddata, function(t, k)
if k == true then
return quads[currentfont()]
else
local parameters = parameters[k]
local quad = parameters and parameters.quad or 0
t[k] = quad
return quad
end
end)
--fonthashes.quads = quaddata
end
---=================================================================---
--- character kerning functionality
---=================================================================---
-- UF changed 2017-07-14
local newUF = node.direct.new
local kern_injector = function (fillup, kern)
if fillup then
local g = newUF("glue")
setfield(g, "stretch", kern)
setfield(g, "stretch_order", 1)
return g
end
local g = newUF("kern")
setfield(g,"kern",kern)
return g
end
-- /UF
local kernable_skip = function (n)
local st = getsubtype (n)
return st == userskip_code
or st == spaceskip_code
or st == xspaceskip_code
end
local function spec_injector (fillup, width, stretch, shrink)
if fillup then
local spec = new_gluespec(width, 2 * stretch, 2 * shrink)
setfield(spec, "stretch_order", 1)
return spec
end
return new_gluespec(width,stretch,shrink)
end
--[[doc--
Caveat lector.
This is an adaptation of the Context character kerning mechanism
that emulates XeTeX-style fontwise letterspacing. Note that in its
present state it is far inferior to the original, which is
attribute-based and ignores font-boundaries. Nevertheless, due to
popular demand the following callback has been added.
--doc]]--
local kernfactors = { } --- fontid -> factor
local kerncharacters
kerncharacters = function (head)
local start = head
local lastfont = nil
local keepligature = letterspace.keepligature --- function
local keeptogether = letterspace.keeptogether --- function
local fillup = false
local identifiers = fonthashes.identifiers
local kernfactors = kernfactors
local firstkern = true
while start do
local id = getid(start)
if id == glyph_code then
--- 1) look up kern factor (slow, but cached rudimentarily)
local krn
local fontid = getfont(start)
do
krn = kernfactors[fontid]
if not krn then
local tfmdata = identifiers[fontid]
if not tfmdata then -- unsafe
tfmdata = font.fonts[fontid]
end
if tfmdata then
fontproperties = tfmdata.properties
if fontproperties then
krn = fontproperties.kerncharacters
end
end
kernfactors[fontid] = krn
end
if not krn or krn == 0 then
firstkern = true
goto nextnode
elseif firstkern then
firstkern = false
if (id ~= disc_code) and (not getfield(start, "components")) then
--- not a ligature, skip node
goto nextnode
end
end
end
if krn == "max" then
krn = .25
fillup = true
else
fillup = false
end
lastfont = fontid
--- 2) resolve ligatures
local c = getfield(start, "components")
if c then
if keepligature and keepligature(start) then
-- keep 'm
c = nil
else
while c do
local s = start
local p, n = getboth (s)
if p then
setlink (p, c)
else
head = c
end
if n then
local tail = find_node_tail(c)
setlink (tail, n)
end
start = c
setfield(s, "components", nil)
free_node(s) --> double free with multipart components
c = getfield (start, "components")
end
end
end -- kern ligature
--- 3) apply the extra kerning
local prev = getprev(start)
if prev then
local pid = getid(prev)
if not pid then
-- nothing
elseif pid == glue_code and kernable_skip(prev) then
local spec = getfield(prev, "spec")
local wd = getfield(spec, "width")
if wd > 0 then
--- formula taken from Context
--- existing_width extended by four times the
--- width times the font’s kernfactor
local newwd = wd + --[[two en to a quad]] 4 * wd * krn
local stretched = (getfield(spec,"stretch") * newwd) / wd
local shrunk = (getfield(spec,"shrink") * newwd) / wd
setfield(prev, "spec",
spec_injector(fillup, newwd, stretched, shrunk))
end
elseif pid == kern_code then
local prev_subtype = getsubtype(prev)
if prev_subtype == kerning_code --- context does this by means of an
or prev_subtype == userkern_code --- attribute; we may need a test
then
local pprev = getprev(prev)
local pprev_id = getid(pprev)
if keeptogether
and pprev_id == glyph_code
and keeptogether(pprev, start)
then
-- keep
else
setsubtype (prev, userkern_code)
local prev_kern = getfield(prev, "kern")
prev_kern = prev_kern + quaddata[lastfont] * krn
setfield (prev, "kern", prev_kern)
end
end
elseif pid == glyph_code then
if getfont(prev) == lastfont then
local prevchar = getchar(prev)
local lastchar = getchar(start)
if keeptogether and keeptogether(prev, start) then
-- keep 'm
elseif identifiers[lastfont] then
local lastfontchars = chardata[lastfont]
if lastfontchars then
local prevchardata = lastfontchars[prevchar]
if not prevchardata then
--- font doesn’t contain the glyph
else
local kern = 0
local kerns = prevchardata.kerns
if kerns then kern = kerns[lastchar] or kern end
krn = kern + quaddata[lastfont]*krn -- here
insert_node_before(head,start,kern_injector(fillup,krn))
end
end
end
else
krn = quaddata[lastfont]*krn -- here
insert_node_before(head,start,kern_injector(fillup,krn))
end
elseif pid == disc_code then
local disc = prev -- disc
local pre, post, replace = getdisc (disc)
local prv = getprev(disc)
local nxt = getnext(disc)
if pre and prv then -- must pair with start.prev
-- this one happens in most cases
local before = copy_node(prv)
setprev(pre, before)
setnext(before, pre)
setprev(before, nil)
pre = kerncharacters (before)
pre = getnext(pre)
setprev(pre, nil)
setfield(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)
setnext(tail, after)
setprev(after, tail)
setnext(after, nil)
post = kerncharacters (post)
setnext(tail, nil)
setfield(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)
setprev(replace, before)
setnext(before, replace)
setprev(before, nil)
setnext(tail, after)
setprev(after, tail)
setnext(after, nil)
replace = kerncharacters (before)
replace = getnext(replace)
setprev(replace, nil)
setnext(getprev(after), nil)
setfield(disc, "replace", replace)
free_node(after)
free_node(before)
elseif identifiers[lastfont] then
if prv
and getid(prv) == glyph_code
and getfont(prv) == lastfont
then
local kern = 0
local prevchar = getchar(prv)
local lastchar = getchar(start)
local lastfontchars = chardata[lastfont]
if lastfontchars then
local prevchardata = lastfontchars[prevchar]
if not prevchardata then
--- font doesn’t contain the glyph
else
local kerns = prevchardata.kerns
if kerns then kern = kerns[lastchar] or kern end
end
end
krn = kern + quaddata[lastfont]*krn -- here
else
krn = quaddata[lastfont]*krn -- here
end
setfield(disc, "replace", kern_injector(false, krn))
end --[[if replace and prv and nxt]]
end --[[if not pid]]
end --[[if prev]]
end --[[if id == glyph_code]]
::nextnode::
if start then
start = getnext(start)
end
end
return head
end
---=================================================================---
--- integration
---=================================================================---
--- · callback: kerncharacters
--- · enabler: enablefontkerning
--- · disabler: disablefontkerning
--- callback wrappers
--- (node_t -> node_t) -> string -> string list -> bool
local registered_as = { } --- procname -> callbacks
local add_processor = function (processor, name, ...)
local callbacks = { ... }
for i=1, #callbacks do
luatexbase.add_to_callback(callbacks[i], processor, name)
end
registered_as[name] = callbacks --- for removal
return true
end
--- string -> bool
local remove_processor = function (name)
local callbacks = registered_as[name]
if callbacks then
for i=1, #callbacks do
luatexbase.remove_from_callback(callbacks[i], name)
end
return true
end
return false --> unregistered
end
--- When font kerning is requested, usually by defining a font with the
--- ``letterspace`` parameter, we inject a wrapper for the
--- ``kerncharacters()`` node processor in the relevant callbacks. This
--- wrapper initially converts the received head node into its “direct”
--- counterpart. Likewise, the callback result is converted back to an
--- ordinary node prior to returning. Internally, ``kerncharacters()``
--- performs all node operations on direct nodes.
--- unit -> bool
local enablefontkerning = function ( )
local handler = function (hd)
local direct_hd = todirect (hd)
logreport ("term", 5, "letterspace",
"kerncharacters() invoked with node.direct interface \z
(``%s`` -> ``%s``)", tostring (hd), tostring (direct_hd))
local direct_hd = kerncharacters (direct_hd)
if not direct_hd then --- bad
logreport ("both", 0, "letterspace",
"kerncharacters() failed to return a valid new head")
end
return tonode (direct_hd)
end
return add_processor( handler
, "luaotfload.letterspace"
, "pre_linebreak_filter"
, "hpack_filter")
end
--- unit -> bool
---al disablefontkerning = function ( )
---eturn remove_processor "luaotfload.letterspace"
---
--[[doc--
Fontwise kerning is enabled via the “kernfactor” option at font
definition time. Unlike the Context implementation which relies on
Luatex attributes, it uses a font property for passing along the
letterspacing factor of a node.
The callback is activated the first time a letterspaced font is
requested and stays active until the end of the run. Since the font
is a property of individual glyphs, every glyph in the entire
document must be checked for the kern property. This is quite
inefficient compared to Context’s attribute based approach, but Xetex
compatibility reduces our options significantly.
--doc]]--
local fontkerning_enabled = false --- callback state
--- fontobj -> float -> unit
local initializefontkerning = function (tfmdata, factor)
if factor ~= "max" then
factor = tonumber (factor) or 0
end
if factor == "max" or factor ~= 0 then
local fontproperties = tfmdata.properties
if fontproperties then
--- hopefully this field stays unused otherwise
fontproperties.kerncharacters = factor
end
if not fontkerning_enabled then
fontkerning_enabled = enablefontkerning ()
end
end
end
--- like the font colorization, fontwise kerning is hooked into the
--- feature mechanism
otffeatures.register {
name = "kernfactor",
description = "kernfactor",
initializers = {
base = initializefontkerning,
node = initializefontkerning,
}
}
--[[doc--
The “letterspace” feature is essentially identical with the above
“kernfactor” method, but scales the factor to percentages to match
Xetex’s behavior. (See the Xetex reference, page 5, section 1.2.2.)
Since Xetex doesn’t appear to have a (documented) “max” keyword, we
assume all input values are numeric.
--doc]]--
local initializecompatfontkerning = function (tfmdata, percentage)
local factor = tonumber (percentage)
if not factor then
logreport ("both", 0, "letterspace",
"Invalid argument to letterspace: %s (type %q), " ..
"was expecting percentage as Lua number instead.",
percentage, type (percentage))
return
end
return initializefontkerning (tfmdata, factor * 0.01)
end
otffeatures.register {
name = "letterspace",
description = "letterspace",
initializers = {
base = initializecompatfontkerning,
node = initializecompatfontkerning,
}
}
--[[example--
See https://bitbucket.org/phg/lua-la-tex-tests/src/tip/pln-letterspace-8-compare.tex
for an example.
--example]]--
--- vim:sw=2:ts=2:expandtab:tw=71