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authorPhilipp Gesang <phg42.2a@gmail.com>2013-05-19 20:08:26 +0200
committerPhilipp Gesang <phg42.2a@gmail.com>2013-05-19 20:08:26 +0200
commit1489b66525103c3762ac1f3dea63214db01a798c (patch)
tree09cf00bfefa18dffb2579530565aaae9f4a7f815 /luaotfload-letterspace.lua
parentbb65ba28ea757225f9bb5707c631e8444db5954e (diff)
downloadluaotfload-1489b66525103c3762ac1f3dea63214db01a798c.tar.gz
add font-dependent letterspacing
Diffstat (limited to 'luaotfload-letterspace.lua')
-rw-r--r--luaotfload-letterspace.lua254
1 files changed, 254 insertions, 0 deletions
diff --git a/luaotfload-letterspace.lua b/luaotfload-letterspace.lua
new file mode 100644
index 0000000..fabf62b
--- /dev/null
+++ b/luaotfload-letterspace.lua
@@ -0,0 +1,254 @@
+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 = next
+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 nodepool = nodes.pool
+local tasks = nodes.tasks
+
+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 fonthashes = fonts.hashes
+local chardata = fonthashes.characters
+local quaddata = fonthashes.quads
+
+typesetters = typesetters or { }
+local typesetters = typesetters
+
+typesetters.kernfont = typesetters.kernfont or { }
+local kernfont = typesetters.kernfont
+
+kernfont.keepligature = false
+kernfont.keeptogether = false
+
+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
+
+local kernfactors = { } --- fontid -> factor
+
+local kerncharacters
+kerncharacters = function (head)
+ local start, done = head, false
+ local lastfont = nil
+ local keepligature = kernfont.keepligature --- function
+ local keeptogether = kernfont.keeptogether --- function
+ local fillup = false
+
+ local identifiers = fonthashes.identifiers
+ local kernfactors = kernfactors
+
+ while start do
+ local attr = start[attribute]
+ 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
+ goto nextnode
+ end
+ end
+
+ if krn == "max" then
+ krn = .25
+ fillup = true
+ else
+ fillup = false
+ end
+
+ lastfont = fontid
+ local c = start.components
+
+ if c then
+ if keepligature and keepligature(start) then
+ -- keep 'm
+ else
+ c = kerncharacters (c)
+ 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
+
+ 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 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
+ 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
+
+kernfont.handler = kerncharacters
+
+--- vim:sw=2:ts=2:expandtab
+