Support 'opbd' (OpenType protrusion) feature

Code scrapped from ConTeXt, AFAIK, no font implements OpenType optical
bounds (on of Linux Libertine font has traces of it), but I plan to use
it in my fonts. The committed feature file is prepared for Pagella, we
can later have font specific feature files like this.

3 files changed, 363 insertions, 11 deletions

diff --git a/otfl-font-dum.lua b/otfl-font-dum.lua
index 8e13b5b..1d79ab1 100644
--- a/otfl-font-dum.lua
+++ b/otfl-font-dum.lua
@@ -155,20 +155,119 @@ fonts.protrusions.setups = fonts.protrusions.setups or { }
 
 local setups  = fonts.protrusions.setups
 
+-- As this is experimental code, users should not depend on it. The
+-- implications are still discussed on the ConTeXt Dev List and we're
+-- not sure yet what exactly the spec is (the next code is tested with
+-- a gyre font patched by / fea file made by Khaled Hosny). The double
+-- trick should not be needed it proper hanging punctuation is used in
+-- which case values < 1 can be used.
+--
+-- preferred (in context, usine vectors):
+--
+-- \definefontfeature[whatever][default][mode=node,protrusion=quality]
+--
+-- using lfbd and rtbd, with possibibility to enable only one side :
+--
+-- \definefontfeature[whocares][default][mode=node,protrusion=yes,  opbd=yes,script=latn]
+-- \definefontfeature[whocares][default][mode=node,protrusion=right,opbd=yes,script=latn]
+--
+-- idem, using multiplier
+--
+-- \definefontfeature[whocares][default][mode=node,protrusion=2,opbd=yes,script=latn]
+-- \definefontfeature[whocares][default][mode=node,protrusion=double,opbd=yes,script=latn]
+--
+-- idem, using named feature file (less frozen):
+--
+-- \definefontfeature[whocares][default][mode=node,protrusion=2,opbd=yes,script=latn,featurefile=texgyrepagella-regularxx.fea]
+
+local function map_opbd_onto_protrusion(tfmdata,value,opbd)
+    local characters, descriptions = tfmdata.characters, tfmdata.descriptions
+    local otfdata = tfmdata.shared.otfdata
+    local singles = otfdata.shared.featuredata.gpos_single
+    local script, language = tfmdata.script, tfmdata.language
+    local done, factor, left, right = false, 1, 1, 1
+    local setup = setups[value]
+    if setup then
+        factor = setup.factor or 1
+        left   = setup.left   or 1
+        right  = setup.right  or 1
+    else
+        factor = tonumber(value) or 1
+    end
+    if opbd ~= "right" then
+        local validlookups, lookuplist = fonts.otf.collect_lookups(otfdata,"lfbd",script,language)
+        if validlookups then
+            for i=1,#lookuplist do
+                local lookup = lookuplist[i]
+                local data = singles[lookup]
+                if data then
+                    if trace_protrusion then
+                        logs.report("fonts","set left protrusion using lfbd lookup '%s'",lookup)
+                    end
+                    for k, v in next, data do
+                    --  local p = - v[3] / descriptions[k].width-- or 1 ~= 0 too but the same
+                        local p = - (v[1] / 1000) * factor * left
+                        characters[k].left_protruding = p
+                        if trace_protrusion then
+                            logs.report("opbd","lfbd -> %s -> 0x%05X (%s) -> %0.03f (%s)",lookup,k,utfchar(k),p,concat(v," "))
+                        end
+                    end
+                    done = true
+                end
+            end
+        end
+    end
+    if opbd ~= "left" then
+        local validlookups, lookuplist = fonts.otf.collect_lookups(otfdata,"rtbd",script,language)
+        if validlookups then
+            for i=1,#lookuplist do
+                local lookup = lookuplist[i]
+                local data = singles[lookup]
+                if data then
+                    if trace_protrusion then
+                        logs.report("fonts","set right protrusion using rtbd lookup '%s'",lookup)
+                    end
+                    for k, v in next, data do
+                    --  local p = v[3] / descriptions[k].width -- or 3
+                        local p = (v[1] / 1000) * factor * right
+                        characters[k].right_protruding = p
+                        if trace_protrusion then
+                            logs.report("opbd","rtbd -> %s -> 0x%05X (%s) -> %0.03f (%s)",lookup,k,utfchar(k),p,concat(v," "))
+                        end
+                    end
+                end
+                done = true
+            end
+        end
+    end
+    tfmdata.auto_protrude = done
+end
+
+-- The opbd test is just there because it was discussed on the
+-- context development list. However, the mentioned fxlbi.otf font
+-- only has some kerns for digits. So, consider this feature not
+-- supported till we have a proper test font.
+
 function fonts.initializers.common.protrusion(tfmdata,value)
     if value then
-        local setup = setups[value]
-        if setup then
-            local factor, left, right = setup.factor or 1, setup.left or 1, setup.right or 1
-            local emwidth = tfmdata.parameters.quad
-            tfmdata.auto_protrude = true
-            for i, chr in next, tfmdata.characters do
-                local v, pl, pr = setup[i], nil, nil
-                if v then
-                    pl, pr = v[1], v[2]
+        local opbd = tfmdata.shared.features.opbd
+        if opbd then
+            -- possible values: left right both yes no (experimental)
+            map_opbd_onto_protrusion(tfmdata,value,opbd)
+        elseif value then
+            local setup = setups[value]
+            if setup then
+                local factor, left, right = setup.factor or 1, setup.left or 1, setup.right or 1
+                local emwidth = tfmdata.parameters.quad
+                tfmdata.auto_protrude = true
+                for i, chr in next, tfmdata.characters do
+                    local v, pl, pr = setup[i], nil, nil
+                    if v then
+                        pl, pr = v[1], v[2]
+                    end
+                    if pl and pl ~= 0 then chr.left_protruding  = left *pl*factor end
+                    if pr and pr ~= 0 then chr.right_protruding = right*pr*factor end
                 end
-                if pl and pl ~= 0 then chr.left_protruding  = left *pl*factor end
-                if pr and pr ~= 0 then chr.right_protruding = right*pr*factor end
             end
         end
     end
diff --git a/tests/opbd.fea b/tests/opbd.fea
new file mode 100644
index 0000000..affc3c5
--- /dev/null
+++ b/tests/opbd.fea
@@ -0,0 +1,244 @@
+
+lookup RightBounds {
+  lookupflag 0;
+    pos \exclam <100 0 0 0>;
+    pos \percent <100 0 0 0>;
+    pos \ampersand <100 0 0 0>;
+    pos \parenright <300 0 0 0>;
+    pos \asterisk <200 0 0 0>;
+    pos \plus <250 0 0 0>;
+    pos \comma <500 0 0 0>;
+    pos \hyphen <500 0 0 0>;
+    pos \period <700 0 0 0>;
+    pos \slash <300 0 0 0>;
+    pos \one <100 0 0 0>;
+    pos \seven <50 0 0 0>;
+    pos \colon <500 0 0 0>;
+    pos \semicolon <500 0 0 0>;
+    pos \question <200 0 0 0>;
+    pos \at <50 0 0 0>;
+    pos \A <50 0 0 0>;
+    pos \K <50 0 0 0>;
+    pos \L <50 0 0 0>;
+    pos \T <50 0 0 0>;
+    pos \V <50 0 0 0>;
+    pos \W <50 0 0 0>;
+    pos \X <50 0 0 0>;
+    pos \Y <50 0 0 0>;
+    pos \k <50 0 0 0>;
+    pos \p <50 0 0 0>;
+    pos \r <50 0 0 0>;
+    pos \v <50 0 0 0>;
+    pos \w <50 0 0 0>;
+    pos \x <50 0 0 0>;
+    pos \y <70 0 0 0>;
+    pos \asciitilde <250 0 0 0>;
+    pos \Agrave <50 0 0 0>;
+    pos \Aacute <50 0 0 0>;
+    pos \Acircumflex <50 0 0 0>;
+    pos \Atilde <50 0 0 0>;
+    pos \Adieresis <50 0 0 0>;
+    pos \Aring <50 0 0 0>;
+    pos \Amacron <50 0 0 0>;
+    pos \Abreve <50 0 0 0>;
+    pos \Aogonek <50 0 0 0>;
+    pos \Kcommaaccent <50 0 0 0>;
+    pos \kcommaaccent <50 0 0 0>;
+    pos \Lacute <50 0 0 0>;
+    pos \Lcommaaccent <50 0 0 0>;
+    pos \Lcaron <50 0 0 0>;
+    pos \Ldot <50 0 0 0>;
+    pos \Lslash <50 0 0 0>;
+    pos \racute <50 0 0 0>;
+    pos \rcommaaccent <50 0 0 0>;
+    pos \rcaron <50 0 0 0>;
+    pos \wcircumflex <50 0 0 0>;
+    pos \ycircumflex <70 0 0 0>;
+    pos \Acaron <50 0 0 0>;
+    pos \Aringacute <50 0 0 0>;
+    pos \Adblgrave <50 0 0 0>;
+    pos \rdblgrave <50 0 0 0>;
+    pos \uni021A <50 0 0 0>;
+    pos \Alpha <50 0 0 0>;
+    pos \Kappa <50 0 0 0>;
+    pos \Lambda <50 0 0 0>;
+    pos \Tau <50 0 0 0>;
+    pos \Ldotbelow <50 0 0 0>;
+    pos \Ldotbelowmacron <50 0 0 0>;
+    pos \rdotaccent <50 0 0 0>;
+    pos \rdotbelow <50 0 0 0>;
+    pos \rdotbelowmacron <50 0 0 0>;
+    pos \Tdotbelow <50 0 0 0>;
+    pos \Tlinebelow <50 0 0 0>;
+    pos \wgrave <50 0 0 0>;
+    pos \wacute <50 0 0 0>;
+    pos \wdieresis <50 0 0 0>;
+    pos \Ahookabove <50 0 0 0>;
+    pos \Acircumflexacute <50 0 0 0>;
+    pos \Acircumflexgrave <50 0 0 0>;
+    pos \Acircumflexhookabove <50 0 0 0>;
+    pos \Acircumflextilde <50 0 0 0>;
+    pos \Acircumflexdotbelow <50 0 0 0>;
+    pos \Abreveacute <50 0 0 0>;
+    pos \Abrevegrave <50 0 0 0>;
+    pos \Abrevehookabove <50 0 0 0>;
+    pos \Abrevetilde <50 0 0 0>;
+    pos \Abrevedotbelow <50 0 0 0>;
+    pos \ygrave <70 0 0 0>;
+    pos \ydotbelow <70 0 0 0>;
+    pos \yhookabove <70 0 0 0>;
+    pos \ytilde <70 0 0 0>;
+    pos \endash <300 0 0 0>;
+    pos \emdash <200 0 0 0>;
+    pos \quoteleft <700 0 0 0>;
+    pos \quoteright <700 0 0 0>;
+    pos \quotedblleft <400 0 0 0>;
+    pos \quotedblright <400 0 0 0>;
+    pos \Aogonekacute <50 0 0 0>;
+    pos \L_uni0303 <50 0 0 0>;
+    pos \T_uni0303 <50 0 0 0>;
+    pos \T_uni0308 <50 0 0 0>;
+} RightBounds;
+
+lookup LeftBounds {
+  lookupflag 0;
+    pos \percent <-100 0 -100 0>;
+    pos \ampersand <-50 0 -50 0>;
+    pos \parenleft <-100 0 -100 0>;
+    pos \asterisk <-200 0 -200 0>;
+    pos \plus <-250 0 -250 0>;
+    pos \hyphen <-400 0 -400 0>;
+    pos \slash <-200 0 -200 0>;
+    pos \one <-100 0 -100 0>;
+    pos \at <-50 0 -50 0>;
+    pos \A <-50 0 -50 0>;
+    pos \J <-50 0 -50 0>;
+    pos \T <-50 0 -50 0>;
+    pos \V <-50 0 -50 0>;
+    pos \W <-50 0 -50 0>;
+    pos \X <-50 0 -50 0>;
+    pos \Y <-50 0 -50 0>;
+    pos \p <-50 0 -50 0>;
+    pos \q <-50 0 -50 0>;
+    pos \v <-50 0 -50 0>;
+    pos \w <-50 0 -50 0>;
+    pos \x <-50 0 -50 0>;
+    pos \y <-50 0 -50 0>;
+    pos \asciitilde <-200 0 -200 0>;
+    pos \Agrave <-50 0 -50 0>;
+    pos \Aacute <-50 0 -50 0>;
+    pos \Acircumflex <-50 0 -50 0>;
+    pos \Atilde <-50 0 -50 0>;
+    pos \Adieresis <-50 0 -50 0>;
+    pos \Aring <-50 0 -50 0>;
+    pos \Amacron <-50 0 -50 0>;
+    pos \Abreve <-50 0 -50 0>;
+    pos \Aogonek <-50 0 -50 0>;
+    pos \Jcircumflex <-50 0 -50 0>;
+    pos \wcircumflex <-50 0 -50 0>;
+    pos \ycircumflex <-50 0 -50 0>;
+    pos \Acaron <-50 0 -50 0>;
+    pos \Aringacute <-50 0 -50 0>;
+    pos \Adblgrave <-50 0 -50 0>;
+    pos \uni021A <-50 0 -50 0>;
+    pos \Alpha <-50 0 -50 0>;
+    pos \Lambda <-50 0 -50 0>;
+    pos \Tau <-50 0 -50 0>;
+    pos \Tdotbelow <-50 0 -50 0>;
+    pos \Tlinebelow <-50 0 -50 0>;
+    pos \wgrave <-50 0 -50 0>;
+    pos \wacute <-50 0 -50 0>;
+    pos \wdieresis <-50 0 -50 0>;
+    pos \Ahookabove <-50 0 -50 0>;
+    pos \Acircumflexacute <-50 0 -50 0>;
+    pos \Acircumflexgrave <-50 0 -50 0>;
+    pos \Acircumflexhookabove <-50 0 -50 0>;
+    pos \Acircumflextilde <-50 0 -50 0>;
+    pos \Acircumflexdotbelow <-50 0 -50 0>;
+    pos \Abreveacute <-50 0 -50 0>;
+    pos \Abrevegrave <-50 0 -50 0>;
+    pos \Abrevehookabove <-50 0 -50 0>;
+    pos \Abrevetilde <-50 0 -50 0>;
+    pos \Abrevedotbelow <-50 0 -50 0>;
+    pos \ygrave <-50 0 -50 0>;
+    pos \ydotbelow <-50 0 -50 0>;
+    pos \yhookabove <-50 0 -50 0>;
+    pos \ytilde <-50 0 -50 0>;
+    pos \endash <-300 0 -300 0>;
+    pos \emdash <-200 0 -200 0>;
+    pos \quoteleft <-500 0 -500 0>;
+    pos \quoteright <-500 0 -500 0>;
+    pos \quotedblleft <-300 0 -300 0>;
+    pos \quotedblright <-300 0 -300 0>;
+    pos \Aogonekacute <-50 0 -50 0>;
+    pos \J_uni030C.cap <-50 0 -50 0>;
+    pos \T_uni0303 <-50 0 -50 0>;
+    pos \T_uni0308 <-50 0 -50 0>;
+} LeftBounds;
+
+feature rtbd {
+
+  script DFLT;
+     language dflt ;
+      lookup RightBounds;
+
+  script grek;
+     language dflt ;
+      lookup RightBounds;
+
+  script latn;
+     language dflt ;
+      lookup RightBounds;
+     language AZE  exclude_dflt;
+      lookup RightBounds;
+     language CRT  exclude_dflt;
+      lookup RightBounds;
+     language MOL  exclude_dflt;
+      lookup RightBounds;
+     language NLD  exclude_dflt;
+      lookup RightBounds;
+     language PLK  exclude_dflt;
+      lookup RightBounds;
+     language ROM  exclude_dflt;
+      lookup RightBounds;
+     language TRK  exclude_dflt;
+      lookup RightBounds;
+
+  script thai;
+     language dflt ;
+      lookup RightBounds;
+} rtbd;
+
+feature lfbd {
+
+  script DFLT;
+     language dflt ;
+      lookup LeftBounds;
+
+  script grek;
+     language dflt ;
+      lookup LeftBounds;
+
+  script latn;
+     language dflt ;
+      lookup LeftBounds;
+     language AZE  exclude_dflt;
+      lookup LeftBounds;
+     language CRT  exclude_dflt;
+      lookup LeftBounds;
+     language MOL  exclude_dflt;
+      lookup LeftBounds;
+     language NLD  exclude_dflt;
+      lookup LeftBounds;
+     language PLK  exclude_dflt;
+      lookup LeftBounds;
+     language ROM  exclude_dflt;
+      lookup LeftBounds;
+     language TRK  exclude_dflt;
+      lookup LeftBounds;
+
+  script thai;
+     language dflt ;
+      lookup LeftBounds;
+} lfbd;
+
diff --git a/tests/opbd.tex b/tests/opbd.tex
new file mode 100644
index 0000000..4c45781
--- /dev/null
+++ b/tests/opbd.tex
@@ -0,0 +1,9 @@
+\input luaotfload.sty
+
+\pdfprotrudechars2 \pdfadjustspacing2
+
+\font\testa=file:texgyrepagella-regular:script=latn                                at 12pt
+\font\testb=file:texgyrepagella-regular:mode=node;script=latn;protrusion=yes;featurefile=opbd.fea;+opbd at 12pt
+\testa \input tufte \par
+\testb \input tufte \par
+\bye