import ``letterspace-support.lua`` as ``luaotfload-extralibs.lua``

from the mercurial source: https://bitbucket.org/phg/characterkerning

1 files changed, 403 insertions, 0 deletions

diff --git a/luaotfload-extralibs.lua b/luaotfload-extralibs.lua
new file mode 100644
index 0000000..f192d1e
--- /dev/null
+++ b/luaotfload-extralibs.lua
@@ -0,0 +1,403 @@
+if not modules then modules = { } end modules ["extralibs"] = {
+    version   = 2.200,
+    comment   = "companion to luaotfload.lua",
+    author    = "Hans Hagen, Philipp Gesang",
+    copyright = "PRAGMA ADE / ConTeXt Development Team",
+    license   = "GPL v.2.0",
+}
+
+-- extralibs: set up an emulation layer to load additional Context
+--            libraries
+
+--===================================================================--
+---                             PREPARE
+--===================================================================--
+
+local getmetatable    = getmetatable
+local require         = require
+local select          = select
+local setmetatable    = setmetatable
+local tonumber        = tonumber
+
+local texattribute    = tex.attribute
+
+local new_node        = node.new
+local copy_node       = node.copy
+
+-----------------------------------------------------------------------
+--- namespace
+-----------------------------------------------------------------------
+
+--- The “typesetters” namespace isn’t bad at all; there is no need
+--- to remove it after loading.
+
+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 namespace          = "kern" --- <= attribute <= plugin.name
+local callback_name      = "typesetters.kerncharacters"
+
+-----------------------------------------------------------------------
+--- node-ini
+-----------------------------------------------------------------------
+
+nodes              = nodes or { } --- should be present with luaotfload
+local bothways     = function (t) return table.swapped (t, t) end
+
+nodes.kerncodes = bothways({
+  [0] = "fontkern",
+  [1] = "userkern",
+  [2] = "accentkern",
+})
+
+nodes.skipcodes = bothways({
+  [  0] = "userskip",
+  [  1] = "lineskip",
+  [  2] = "baselineskip",
+  [  3] = "parskip",
+  [  4] = "abovedisplayskip",
+  [  5] = "belowdisplayskip",
+  [  6] = "abovedisplayshortskip",
+  [  7] = "belowdisplayshortskip",
+  [  8] = "leftskip",
+  [  9] = "rightskip",
+  [ 10] = "topskip",
+  [ 11] = "splittopskip",
+  [ 12] = "tabskip",
+  [ 13] = "spaceskip",
+  [ 14] = "xspaceskip",
+  [ 15] = "parfillskip",
+  [ 16] = "thinmuskip",
+  [ 17] = "medmuskip",
+  [ 18] = "thickmuskip",
+  [100] = "leaders",
+  [101] = "cleaders",
+  [102] = "xleaders",
+  [103] = "gleaders",
+})
+
+-----------------------------------------------------------------------
+--- node-res
+-----------------------------------------------------------------------
+
+nodes.pool        = nodes.pool or { }
+local pool        = nodes.pool
+
+local kern        = new_node("kern", nodes.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.gluespec = function (width, stretch, shrink, 
+                          stretch_order, shrink_order)
+  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
+  return s
+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 markdata           = fonthashes.marks
+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 characters = identifiers[k].characters
+      t[k] = characters
+      return characters
+    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
+
+if not markdata then
+  markdata = { }
+  setmetatableindex(markdata, function(t, k)
+    if k == true then
+      return marks[currentfont()]
+    else
+      local resources = identifiers[k].resources or { }
+      local marks = resources.marks or { }
+      t[k] = marks
+      return marks
+    end
+  end)
+  fonthashes.marks = markdata
+end
+
+interfaces                = interfaces or { }
+interfaces.variables      = interfaces.variables or { }
+interfaces.variables.max  = "max"
+
+-----------------------------------------------------------------------
+--- attr-ini
+-----------------------------------------------------------------------
+
+attributes = attributes or { } --- to be removed with cleanup
+
+local hidden = {
+  a_kerns     = luatexbase.new_attribute("typo-krn:a_kerns",    true),
+  a_fontkern  = luatexbase.new_attribute("typo-krn:a_fontkern", true),
+}
+
+attributes.private = attributes.private or function (attr_name)
+  local res = hidden[attr_name]
+  if not res then
+    res = luatexbase.new_attribute(attr_name)
+  end
+  return res
+end
+
+attributes.unsetvalue = luatexbase.get_unset_value()
+
+-----------------------------------------------------------------------
+--- luat-sto
+-----------------------------------------------------------------------
+
+--- Storage is so ridiculously well designed in Context it’s a pity
+--- we can’t just force every package author to use it.
+
+storage           = storage or { }
+storage.register  = storage.register or function (...)
+  local t = { ... }
+  --- sorry
+  return t
+end
+
+-----------------------------------------------------------------------
+--- node-fin
+-----------------------------------------------------------------------
+
+local plugin_store = { }
+
+local installattributehandler = function (plugin)
+  --- Context has some load() magic here.
+  plugin_store[plugin.name] = plugin.processor
+end
+
+nodes.installattributehandler = installattributehandler
+
+-----------------------------------------------------------------------
+--- node-tsk
+-----------------------------------------------------------------------
+
+nodes.tasks               = nodes.tasks or { }
+nodes.tasks.enableaction  = function () end
+
+-----------------------------------------------------------------------
+--- core-ctx
+-----------------------------------------------------------------------
+
+commands = commands or { }
+
+--===================================================================--
+---                              LOAD
+--===================================================================--
+
+--- we should be ready at this moment to insert the library
+
+require "typo-krn"
+
+--===================================================================--
+---                              CLEAN
+--===================================================================--
+--- interface
+-----------------------------------------------------------------------
+
+local factors           = kerns.factors
+local mapping           = kerns.mapping
+local unsetvalue        = attributes.unset_value
+local process_kerns     = plugin_store.kern
+
+local kerncharacters = function (head)
+  return process_kerns("kerns", hidden.a_kerns, head)
+end
+
+--- callback wrappers
+local add_kern_processor = function (...)
+  for i=1, select("#", ...) do
+    luatexbase.add_to_callback(
+      select(i, ...), kerncharacters, callback_name
+    )
+  end
+end
+local remove_kern_processor = function (...)
+  for i=1, select("#", ...) do
+    luatexbase.remove_from_callback(
+      select(i, ...), kerncharacters, callback_name
+    )
+  end
+end
+
+--- we use the same callbacks as a node processor in Context
+kerns.enablecharacterkerning = function ( )
+  add_kern_processor("pre_linebreak_filter", "hpack_filter")
+end
+
+kerns.disablecharacterkerning = function ( )
+  remove_kern_processor("pre_linebreak_filter", "hpack_filter")
+end
+
+local enabled = false --- callback state
+
+--- we just replace the kern enabler with our modified version
+kerns.set = function (factor)
+  if factor ~= v_max then
+    factor = tonumber(factor) or 0
+  end
+  if factor == v_max or factor ~= 0 then
+    if not enabled then
+      kerns.enablecharacterkerning()
+      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[hidden.a_kerns] = factor
+  return factor
+end
+
+
+-----------------------------------------------------------------------
+--- options
+-----------------------------------------------------------------------
+
+kerns.keepligature = false --- supposed to be of type function
+kerns.keeptogether = false --- supposed to be of type function
+
+-----------------------------------------------------------------------
+--- erase fake Context layer
+-----------------------------------------------------------------------
+
+attributes     = nil
+--commands       = nil  --- used in lualibs
+storage        = nil    --- not to confuse with utilities.storage
+nodes.tasks    = nil
+
+collectgarbage"collect"
+
+--[[example--
+
+\input luaotfload.sty
+\RequireLuaModule{letterspace-support.lua}
+\def\setcharacterkerning#1{% #1 factor : float
+  \directlua{typesetters.kerns.set(0.618)}%
+}
+%directlua{typesetters.kerns.enablecharacterkerning()}
+
+\font\iwona       = "name:Iwona:mode=node"                at 42pt
+\font\lmregular   = "name:Latin Modern Roman:mode=node"   at 42pt
+
+{\iwona
+ foo
+ {\setcharacterkerning{0.618}%
+  bar}
+ baz}
+
+{\lmregular
+ foo {\setcharacterkerning{0.125}ff fi ffi fl Th} baz}
+
+{\lmregular
+ \directlua{ %% I’m not exactly sure how those work
+    typesetters.kerns.keepligature = function (start)
+      print("[liga]", start)
+      return true
+    end
+    typesetters.kerns.keeptogether = function (start)
+      print("[keeptogether]", start)
+      return true
+    end}%
+ foo {\setcharacterkerning{0.125}ff fi ffi fl Th} baz}
+
+\bye
+--example]]--
+
+-- vim:ts=2:sw=2:expandtab