summaryrefslogtreecommitdiff
path: root/luaotfload-letterspace.lua
diff options
context:
space:
mode:
Diffstat (limited to 'luaotfload-letterspace.lua')
-rw-r--r--luaotfload-letterspace.lua544
1 files changed, 0 insertions, 544 deletions
diff --git a/luaotfload-letterspace.lua b/luaotfload-letterspace.lua
deleted file mode 100644
index 20f29f5..0000000
--- a/luaotfload-letterspace.lua
+++ /dev/null
@@ -1,544 +0,0 @@
-if not modules then modules = { } end modules ['letterspace'] = {
- version = "2.5",
- 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"
-}
-
-local log = luaotfload.log
-local report = log.report
-
-local getmetatable = getmetatable
-local require = require
-local setmetatable = setmetatable
-local tonumber = tonumber
-
-local next = next
-local nodes, node, fonts = nodes, node, fonts
-
-local find_node_tail = node.tail or node.slide
-local free_node = node.free
-local copy_node = node.copy
-local new_node = node.new
-local insert_node_before = node.insert_before
-
-local nodepool = nodes.pool
-
-local new_kern = nodepool.kern
-local new_glue = nodepool.glue
-
-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 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"
- }
-
-kerncodes.kerning = kerncodes.fontkern --- idiosyncrasy
-local kerning_code = kerncodes.kerning
-local userkern_code = kerncodes.userkern
-
-
------------------------------------------------------------------------
---- node-res
------------------------------------------------------------------------
-
-nodes.pool = nodes.pool or { }
-local pool = nodes.pool
-
-local kern = new_node ("kern", kerncodes.userkern)
-local glue_spec = new_node "glue_spec"
-
-pool.kern = function (k)
- local n = copy_node (kern)
- n.kern = k
- return n
-end
-
-pool.glue = function (width, stretch, shrink,
- stretch_order, shrink_order)
- local n = new_node"glue"
- if not width then
- -- no spec
- elseif width == false or tonumber(width) then
- local s = copy_node(glue_spec)
- if width then s.width = width end
- if stretch then s.stretch = stretch end
- if shrink then s.shrink = shrink end
- if stretch_order then s.stretch_order = stretch_order end
- if shrink_order then s.shrink_order = shrink_order end
- n.spec = s
- else
- -- shared
- 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
----=================================================================---
-
-local kern_injector = function (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
-
---[[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, done = head, false
- 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 = start.id
- if id == glyph_code then
-
- --- 1) look up kern factor (slow, but cached rudimentarily)
- local krn
- local fontid = start.font
- 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 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 = start.components
-
- if c then
- if keepligature and keepligature(start) then
- -- keep 'm
- else
- --- c = kerncharacters (c) --> taken care of after replacing
- 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 -- kern ligature
-
- --- 3) apply the extra kerning
- local prev = start.prev
- if prev then
- local pid = prev.id
-
- if not pid then
- -- nothing
-
- elseif pid == kern_code then
- if prev.subtype == kerning_code --- context does this by means of an
- or prev.subtype == userkern_code --- attribute; we may need a test
- then
- if keeptogether and prev.prev.id == glyph_code and keeptogether(prev.prev,start) then
- -- keep
- else
- 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
- elseif identifiers[lastfont] then
- 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 = kerncharacters (before)
- 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 = kerncharacters (post)
- 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 = kerncharacters (before)
- replace = replace.next
- replace.prev = nil
- after.prev.next = nil
- disc.replace = replace
- free_node(after)
- free_node(before)
- elseif identifiers[lastfont] then
- 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
- end
-
- ::nextnode::
- if start then
- start = start.next
- end
- end
- return head, done
-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
-
---- now for the simplistic variant
---- unit -> bool
-local enablefontkerning = function ( )
- return add_processor( kerncharacters
- , "luaotfload.letterspace"
- , "pre_linebreak_filter"
- , "hpack_filter")
-end
-
---- unit -> bool
-local disablefontkerning = function ( )
- return remove_processor "luaotfload.letterspace"
-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
- report ("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
-