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Diffstat (limited to 'tex/context/base/mkiv/font-imp-reorder.lua')
| -rw-r--r-- | tex/context/base/mkiv/font-imp-reorder.lua | 172 |
1 files changed, 172 insertions, 0 deletions
diff --git a/tex/context/base/mkiv/font-imp-reorder.lua b/tex/context/base/mkiv/font-imp-reorder.lua new file mode 100644 index 000000000..250aa47c6 --- /dev/null +++ b/tex/context/base/mkiv/font-imp-reorder.lua @@ -0,0 +1,172 @@ +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" +} + +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, + } +} |