summaryrefslogtreecommitdiff
path: root/src/luaotfload-letterspace.lua
diff options
context:
space:
mode:
authorPhilipp Gesang <phg@phi-gamma.net>2015-11-26 23:12:49 +0100
committerPhilipp Gesang <phg@phi-gamma.net>2015-11-26 23:12:49 +0100
commitfec6aa52281f689c7cfdd7b379f5dccbc2ce7cef (patch)
tree2c0c0709d729127d64837dd4f7c796559d73e7a0 /src/luaotfload-letterspace.lua
parent54654688c8aa643ec9cc068eb25464d40ead84a0 (diff)
downloadluaotfload-fec6aa52281f689c7cfdd7b379f5dccbc2ce7cef.tar.gz
[letterspace] fix handling of interword space
Fix https://github.com/lualatex/luaotfload/issues/297 Interword glue hasn’t been considered yet. This again adapts the relevant logic from Context to our letterspacing method. The code is deliberately simplistic and will most likely not address all constellations of a glue preceding a character.
Diffstat (limited to 'src/luaotfload-letterspace.lua')
-rw-r--r--src/luaotfload-letterspace.lua94
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