diff options
Diffstat (limited to 'src/luaotfload-letterspace.lua')
| -rw-r--r-- | src/luaotfload-letterspace.lua | 94 |
1 files changed, 71 insertions, 23 deletions
diff --git a/src/luaotfload-letterspace.lua b/src/luaotfload-letterspace.lua index ab81881..5fa25f9 100644 --- a/src/luaotfload-letterspace.lua +++ b/src/luaotfload-letterspace.lua @@ -6,6 +6,9 @@ if not modules then modules = { } end modules ['letterspace'] = { license = "see context related readme files" } +--- This code diverged quite a bit from its origin in Context. Please +--- do *not* report bugs on the Context list. + local log = luaotfload.log local logreport = log.report @@ -39,7 +42,6 @@ local new_node = nodedirect.new local nodepool = nodedirect.pool local new_kern = nodepool.kern -local new_glue = nodepool.glue local nodecodes = nodes.nodecodes @@ -47,6 +49,7 @@ local glyph_code = nodecodes.glyph local kern_code = nodecodes.kern local disc_code = nodecodes.disc local math_code = nodecodes.math +local glue_code = nodecodes.glue local fonthashes = fonts.hashes local chardata = fonthashes.characters @@ -81,11 +84,17 @@ local kerncodes = bothways { [0] = "fontkern" , [1] = "userkern" , [2] = "accentkern" } +local skipcodes = bothways { [0] = "userskip" + , [13] = "spaceskip" + , [14] = "xspaceskip" + } -kerncodes.kerning = kerncodes.fontkern --- idiosyncrasy -local kerning_code = kerncodes.kerning -local userkern_code = kerncodes.userkern - +kerncodes.kerning = kerncodes.fontkern --- idiosyncrasy +local kerning_code = kerncodes.kerning +local userkern_code = kerncodes.userkern +local userskip_code = skipcodes.userskip +local spaceskip_code = skipcodes.spaceskip +local xspaceskip_code = skipcodes.xspaceskip ----------------------------------------------------------------------- --- node-res @@ -93,19 +102,30 @@ local userkern_code = kerncodes.userkern local glue_spec = new_node "glue_spec" -nodepool.glue = function (width, stretch, shrink, - stretch_order, shrink_order) +local new_gluespec = function (width, + stretch, shrink, + stretch_order, shrink_order) + local spec = copy_node(glue_spec) + if width then setfield(spec, "width" , width ) end + if stretch then setfield(spec, "stretch" , stretch ) end + if shrink then setfield(spec, "shrink" , shrink ) end + if stretch_order then setfield(spec, "stretch_order", stretch_order) end + if shrink_order then setfield(spec, "shrink_order" , shrink_order ) end + return spec +end + +local new_glue = function (width, stretch, shrink, + stretch_order, shrink_order) local n = new_node "glue" - if not width then + if not width then return n end -- no spec - elseif width == false or tonumber(width) then - local s = copy_node(glue_spec) - if width then setfield(s, "width" , width ) end - if stretch then setfield(s, "stretch" , stretch ) end - if shrink then setfield(s, "shrink" , shrink ) end - if stretch_order then setfield(s, "stretch_order", stretch_order) end - if shrink_order then setfield(s, "shrink_order" , shrink_order ) end - setfield(n, "spec", s) + if width == false then + local width = tonumber(width) + if width then + setfield(n, "spec", + new_gluespec(width, stretch, shrink, + stretch_order, shrink_order)) + end else -- shared setfield(n, "spec", copy_node(width)) @@ -198,6 +218,22 @@ local kern_injector = function (fillup, kern) return new_kern(kern) end +local kernable_skip = function (n) + local st = getsubtype (n) + return st == userskip_code + or st == spaceskip_code + or st == xspaceskip_code +end + +local function spec_injector (fillup, width, stretch, shrink) + if fillup then + local spec = new_gluespec(width, 2 * stretch, 2 * shrink) + setfield(spec, "stretch_order", 1) + return spec + end + return new_gluespec(width,stretch,shrink) +end + --[[doc-- Caveat lector. @@ -221,13 +257,11 @@ kerncharacters = function (head) local identifiers = fonthashes.identifiers local kernfactors = kernfactors - local firstkern = true while start do local id = getid(start) if id == glyph_code then - --- 1) look up kern factor (slow, but cached rudimentarily) local krn local fontid = getfont(start) @@ -304,6 +338,21 @@ kerncharacters = function (head) if not pid then -- nothing + elseif pid == glue_code and kernable_skip(prev) then + local spec = getfield(prev, "spec") + local wd = getfield(spec, "width") + if wd > 0 then + --- formula taken from Context + --- existing_width extended by four times the + --- width times the font’s kernfactor + local newwd = wd + --[[two en to a quad]] 4 * wd * krn + local stretched = (getfield(spec,"stretch") * newwd) / wd + local shrunk = (getfield(spec,"shrink") * newwd) / wd + setfield(prev, "spec", + spec_injector(fillup, newwd, stretched, shrunk)) + done = true + end + elseif pid == kern_code then local prev_subtype = getsubtype(prev) if prev_subtype == kerning_code --- context does this by means of an @@ -412,11 +461,10 @@ kerncharacters = function (head) krn = quaddata[lastfont]*krn -- here end setfield(disc, "replace", kern_injector(false, krn)) - end - - end - end - end + end --[[if replace and prv and nxt]] + end --[[if not pid]] + end --[[if prev]] + end --[[if id == glyph_code]] ::nextnode:: if start then |