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-rw-r--r--macros/luatex/generic/luaotfload/luaotfload-letterspace.lua578
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diff --git a/macros/luatex/generic/luaotfload/luaotfload-letterspace.lua b/macros/luatex/generic/luaotfload/luaotfload-letterspace.lua
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+++ b/macros/luatex/generic/luaotfload/luaotfload-letterspace.lua
@@ -0,0 +1,578 @@
+-----------------------------------------------------------------------
+-- FILE: luaotfload-letterspace.lua
+-- DESCRIPTION: part of luaotfload / letterspacing
+-----------------------------------------------------------------------
+
+local ProvidesLuaModule = {
+ name = "luaotfload-letterspace",
+ version = "2.991", --TAGVERSION
+ date = "2019-08-11", --TAGDATE
+ description = "luaotfload submodule / color",
+ license = "GPL v2.0",
+ copyright = "PRAGMA ADE / ConTeXt Development Team",
+ author = "Hans Hagen, PRAGMA-ADE, Hasselt NL; adapted by Philipp Gesang, Ulrike Fischer, Marcel Krüger"
+}
+
+if luatexbase and luatexbase.provides_module then
+ luatexbase.provides_module (ProvidesLuaModule)
+end
+
+--- This code diverged quite a bit from its origin in Context. Please
+--- do *not* report bugs on the Context list.
+
+local logreport = luaotfload.log.report
+
+local getmetatable = getmetatable
+local setmetatable = setmetatable
+local tonumber = tonumber
+local unpack = table.unpack
+
+local next = next
+local node, fonts = node, fonts
+
+local nodedirect = node.direct
+
+local getfield = nodedirect.getfield
+local setfield = nodedirect.setfield
+
+local getfont = nodedirect.getfont
+local getid = nodedirect.getid
+
+local getnext = nodedirect.getnext
+local setnext = nodedirect.setnext
+
+local getprev = nodedirect.getprev
+local setprev = nodedirect.setprev
+
+local getboth = nodedirect.getboth
+
+local setlink = nodedirect.setlink
+
+local getdisc = nodedirect.getdisc
+local setdisc = nodedirect.setdisc
+
+local getsubtype = nodedirect.getsubtype
+local setsubtype = nodedirect.setsubtype
+
+local getchar = nodedirect.getchar
+local setchar = nodedirect.setchar
+
+local getkern = nodedirect.getkern
+local setkern = nodedirect.setkern
+
+local getglue = nodedirect.getglue
+local setglue = nodedirect.setglue
+
+local find_node_tail = nodedirect.tail
+local todirect = nodedirect.todirect
+local tonode = nodedirect.tonode
+
+local insert_node_before = nodedirect.insert_before
+local free_node = nodedirect.free
+local copy_node = nodedirect.copy
+local new_node = nodedirect.new
+
+local glyph_code = node.id"glyph"
+local kern_code = node.id"kern"
+local disc_code = node.id"disc"
+local glue_code = node.id"glue"
+local whatsit_code = node.id"whatsit"
+
+local fonthashes = fonts.hashes
+local identifiers = fonthashes.identifiers
+local chardata = fonthashes.characters
+local otffeatures = fonts.constructors.newfeatures "otf"
+
+local function getprevreal(n)
+ repeat
+ n = getprev(n)
+ until not n or getid(n) ~= whatsit_code
+ return n
+end
+local function getnextreal(n)
+ repeat
+ n = getnext(n)
+ until not n or getid(n) ~= whatsit_code
+ return n
+end
+
+--[[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
+
+local lectured = false
+letterspace.keepligature = true
+letterspace.keeptogether = false
+letterspace.keepwordspacing = false
+
+---=================================================================---
+--- preliminary definitions
+---=================================================================---
+-- We set up a layer emulating some Context internals that are needed
+-- for the letterspacing callback.
+-----------------------------------------------------------------------
+--- node-ini
+-----------------------------------------------------------------------
+
+local kerning_code = 0
+local userkern_code = 1
+local userskip_code = 0
+local spaceskip_code = 13
+local xspaceskip_code = 14
+
+if not chardata then
+ chardata = { }
+ table.setmetatableindex(chardata, function(t, k)
+ if k == true then
+ return chardata[currentfont()]
+ else
+ local tfmdata = font.getfont(k) or font.fonts[k]
+ if tfmdata then
+ local characters = tfmdata.characters
+ t[k] = characters
+ return characters
+ end
+ end
+ end)
+ fonthashes.characters = chardata
+end
+
+---=================================================================---
+--- character kerning functionality
+---=================================================================---
+
+-- UF changed 2017-07-14
+local kern_injector = function (fillup, kern)
+ if fillup then
+ local g = new_node(glue_code)
+ setglue(g, 0, kern, 0, 1, 0)
+ return g
+ end
+ local g = new_node(kern_code)
+ setkern(g,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
+
+--[[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 kernamounts = table.setmetatableindex(function (t, f) --- fontid -> {kern, fill}
+ local tfmdata = font.getfont(f) or font.fonts[f]
+ if tfmdata then
+ local fontproperties = tfmdata.properties
+ local fontparameters = tfmdata.parameters
+ if fontproperties and fontparameters then
+ local r
+ if fontproperties.kerncharacters == "max" then
+ r = {fontparameters.quad/4, true}
+ elseif fontproperties.kerncharacters then
+ r = {fontproperties.kerncharacters * fontparameters.quad, false}
+ else
+ r = {}
+ end
+ t[f] = r
+ return r
+ end
+ end
+ return {}
+end)
+
+local kerncharacters
+kerncharacters = function (head)
+ local start = head
+ local lastfont = nil
+ local keeptogether = letterspace.keeptogether --- function
+ local keepligature = letterspace.keepligature
+-- if not lectured and keepligature ~= true then
+-- logreport ("both", 0, "letterspace",
+-- "Breaking ligatures through letterspacing is deprecated and "
+-- .. "will be removed soon. Please disable unwanted ligatures through "
+-- .. "font features instead and reset luaotfload.letterspace.keepligature "
+-- .. "to true to maintain compatibility with future versions of luaotfload.")
+-- lectured = true
+-- end
+ if type(keepligature) ~= "function" then
+ local savedligature = keepligature
+ keepligature = function() return savedligature end
+ end
+ local keepwordspacing = letterspace.keepwordspacing
+ if type(keepwordspacing) ~= "function" then
+ local savedwordspacing = keepwordspacing
+ keepwordspacing = function() return savedwordspacing end
+ end
+
+ local kernamounts = kernamounts
+ 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 fontid = getfont(start)
+ local krn, fillup = unpack(kernamounts[fontid])
+ 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
+
+ lastfont = fontid
+
+ --- 2) resolve ligatures
+ local c = getfield(start, "components")
+
+ if c then
+ if 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 = getprevreal(start)
+ if prev then
+ local pid = getid(prev)
+
+ if not pid then
+ -- nothing
+
+ elseif pid == glue_code and kernable_skip(prev)
+ and not keepwordspacing(prev, lastfont) then
+ local wd, stretch, shrink = getglue(prev)
+ if wd > 0 then
+ local newwd = wd + krn
+ local stretched = (stretch * newwd) / wd
+ local shrunk = (shrink * newwd) / wd
+ if fillup then
+ setglue(prev, newwd, 2 * stretched, 2 * shrunk, 1, 0)
+ else
+ setglue(prev, newwd, stretched, shrunk, 0, 0)
+ end
+ 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 = getprevreal(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 = getkern(prev)
+ prev_kern = prev_kern + krn
+ setkern (prev, 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 + krn -- here
+ insert_node_before(head,start,kern_injector(fillup,krn))
+ end
+ end
+ end
+ else
+ 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 = getprevreal(disc)
+ local nxt = getnextreal(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)
+ post = kerncharacters (post)
+ setnext(getprev(after), 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 + 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
+
+--- 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
+
+--[[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
+