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if not modules then modules = { } end modules ['font-imp-reorder'] = {
version = 1.001,
comment = "companion to font-ini.mkiv and hand-ini.mkiv",
author = "Hans Hagen, PRAGMA-ADE, Hasselt NL",
copyright = "PRAGMA ADE / ConTeXt Development Team",
license = "see context related readme files"
}
if not context then return end
local next = next
local find = string.find
local sortedhash, sortedkeys, sort = table.sortedhash, table.sortedkeys, table.sort
local fonts = fonts
local otf = fonts.handlers.otf
local registerotffeature = otf.features.register
-- This is a rather special test-only feature that I added for the sake of testing
-- Idris's husayni. We wanted to know if uniscribe obeys the order of lookups in a
-- font, in spite of what the description of handling arabic suggests. And indeed,
-- mixed-in lookups of other features (like all these ss* in husayni) are handled
-- the same in context as in uniscribe. If one sets reorderlookups=arab then we sort
-- according to the "assumed" order so e.g. the ss* move to after the standard
-- features. The observed difference in rendering is an indication that uniscribe is
-- quite faithful to the font (while e.g. tests with the hb plugin demonstrate some
-- interference, apart from some hard coded init etc expectations). Anyway, it means
-- that we're okay with the (generic) node processor. A pitfall is that in context
-- we can actually control more, so we can trigger an analyze pass with e.g.
-- dflt/dflt while the libraries depend on the script settings for that. Uniscribe
-- probably also parses the string and when seeing arabic will follow a different
-- code path, although it seems to treat all features equal.
local trace_reorder = trackers.register("fonts.reorderlookups",function(v) trace_reorder = v end)
local report_reorder = logs.reporter("fonts","reorder")
local vectors = { }
vectors.arab = {
gsub = {
ccmp = 1,
isol = 2,
fina = 3,
medi = 4,
init = 5,
rlig = 6,
rclt = 7,
calt = 8,
liga = 9,
dlig = 10,
cswh = 11,
mset = 12,
},
gpos = {
curs = 1,
kern = 2,
mark = 3,
mkmk = 4,
},
}
local function compare(a,b)
local what_a = a.what
local what_b = b.what
if what_a ~= what_b then
return a.index < b.index
end
local when_a = a.when
local when_b = b.when
if when_a == when_b then
return a.index < b.index
else
return when_a < when_b
end
end
function otf.reorderlookups(tfmdata,vector)
local order = vectors[vector]
if not order then
return
end
local oldsequences = tfmdata.resources.sequences
if oldsequences then
local sequences = { }
for i=1,#oldsequences do
sequences[i] = oldsequences[i]
end
for i=1,#sequences do
local s = sequences[i]
local features = s.features
local kind = s.type
local index = s.index
if features then
local when
local what
for feature in sortedhash(features) do
if not what then
what = find(kind,"^gsub") and "gsub" or "gpos"
end
local newwhen = order[what][feature]
if not newwhen then
-- skip
elseif not when then
when = newwhen
elseif newwhen < when then
when = newwhen
end
end
s.ondex = s.index
s.index = i
s.what = what == "gsub" and 1 or 2
s.when = when or 99
else
s.ondex = s.index
s.index = i
s.what = 1
s.when = 99
end
end
sort(sequences,compare)
local swapped = 0
for i=1,#sequences do
local sequence = sequences[i]
local features = sequence.features
if features then
local index = sequence.index
if index ~= i then
swapped = swapped + 1
end
if trace_reorder then
if swapped == 1 then
report_reorder()
report_reorder("start swapping lookups in font %!font:name!",tfmdata)
report_reorder()
report_reorder("gsub order: % t",table.swapped(order.gsub))
report_reorder("gpos order: % t",table.swapped(order.gpos))
report_reorder()
end
report_reorder("%03i : lookup %03i, type %s, sorted %2i, moved %s, % t",
i,index,sequence.what == 1 and "gsub" or "gpos",sequence.when or 99,
(index > i and "-") or (index < i and "+") or "=",sortedkeys(features))
end
end
sequence.what = nil
sequence.when = nil
sequence.index = sequence.ondex
end
if swapped > 0 then
if trace_reorder then
report_reorder()
report_reorder("stop swapping lookups, %i lookups swapped",swapped)
report_reorder()
end
tfmdata.shared.reorderedsequences = sequences
end
end
end
-- maybe delay till ra is filled
local function initialize(tfmdata,key,value)
if value then
otf.reorderlookups(tfmdata,value)
end
end
registerotffeature {
name = "reorderlookups",
description = "reorder lookups",
manipulators = {
base = initialize,
node = initialize,
}
}
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