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Diffstat (limited to 'tex/context/base/typo-krn.lua')
| -rw-r--r-- | tex/context/base/typo-krn.lua | 223 |
1 files changed, 223 insertions, 0 deletions
diff --git a/tex/context/base/typo-krn.lua b/tex/context/base/typo-krn.lua new file mode 100644 index 000000000..746773e0a --- /dev/null +++ b/tex/context/base/typo-krn.lua @@ -0,0 +1,223 @@ +if not modules then modules = { } end modules ['typo-krn'] = { + version = 1.001, + comment = "companion to typo-krn.mkiv", + author = "Hans Hagen, PRAGMA-ADE, Hasselt NL", + copyright = "PRAGMA ADE / ConTeXt Development Team", + license = "see context related readme files" +} + +local utf = unicode.utf8 + +local next, type = next, type +local utfchar = utf.char + +local has_attribute = node.has_attribute +local unset_attribute = node.unset_attribute +local find_node_tail = node.tail or node.slide +local free_node = node.free +local copy_node = node.copy +local insert_node_before = node.insert_before +local insert_node_after = node.insert_after +local make_glue_spec = nodes.glue_spec +local make_kern_node = nodes.kern + +local glyph = node.id("glyph") +local kern = node.id("kern") +local disc = node.id('disc') +local glue = node.id('glue') +local hlist = node.id('hlist') +local vlist = node.id('vlist') + +local fontdata = fonts.identifiers +local chardata = fonts.characters +local quaddata = fonts.quads + +kerns = kerns or { } +kerns.mapping = kerns.mapping or { } +kerns.factors = kerns.factors or { } +kerns.attribute = attributes.private("kern") + +storage.register("kerns/mapping", kerns.mapping, "kerns.mapping") +storage.register("kerns/factors", kerns.factors, "kerns.factors") + +local mapping = kerns.mapping +local factors = kerns.factors + +function kerns.setspacing(factor) + local a = factors[factor] + if not a then + a = #mapping + 1 + factors[factors], mapping[a] = a, factor + end + tex.attribute[kerns.attribute] = a + return a +end + +-- one must use liga=no and mode=base and kern=yes +-- use more helpers +-- make sure it runs after all others +-- there will be a width adaptor field in nodes so this will change +-- todo: interchar kerns / disc nodes / can be made faster + +local function process(namespace,attribute,head,force) + local scale = tex.scale -- will go + local start, done, lastfont = head, false, nil + while start do + -- faster to test for attr first + local attr = force or has_attribute(start,attribute) + if attr and attr > 0 then + unset_attribute(start,attribute) + local krn = mapping[attr] + if krn and krn ~= 0 then + local id = start.id + if id == glyph then + lastfont = start.font + local c = start.components + if c then + local s = start + local tail = find_node_tail(c) + if s.prev then + s.prev.next = c + c.prev = s.prev + else + head = c + end + if s.next then + s.next.prev = tail + end + tail.next = s.next + start = c + start.attr = s.attr + s.attr = nil + s.components = nil + free_node(s) + done = true + end + local prev = start.prev + if prev then + local pid = prev.id + if not pid then + -- nothing + elseif pid == kern and prev.subtype == 0 then + prev.subtype = 1 + prev.kern = prev.kern + scale(quaddata[lastfont],krn) + done = true + elseif pid == glyph then + if prev.font == lastfont then + local prevchar, lastchar = prev.char, start.char + local kerns = chardata[lastfont][prevchar].kerns + local kern = kerns and kerns[lastchar] or 0 + krn = scale(kern+quaddata[lastfont],krn) + else + krn = scale(quaddata[lastfont],krn) + end + insert_node_before(head,start,make_kern_node(krn)) + done = true + elseif pid == disc then + -- a bit too complicated, we can best not copy and just calculate + -- but we could have multiple glyphs involved so ... + local disc = prev -- disc + local pre, post, replace = disc.pre, disc.post, disc.replace + local prv, nxt = disc.prev, disc.next + if pre and prv then -- must pair with start.prev + -- this one happens in most cases + local before = copy_node(prv) + pre.prev = before + before.next = pre + before.prev = nil + pre = process(namespace,attribute,before,attr) + pre = pre.next + pre.prev = nil + disc.pre = pre + free_node(before) + end + if post and nxt then -- must pair with start + local after = copy_node(nxt) + local tail = find_node_tail(post) + tail.next = after + after.prev = tail + after.next = nil + post = process(namespace,attribute,post,attr) + tail.next = nil + disc.post = post + free_node(after) + end + if replace and prv and nxt then -- must pair with start and start.prev + local before = copy_node(prv) + local after = copy_node(nxt) + local tail = find_node_tail(replace) + replace.prev = before + before.next = replace + before.prev = nil + tail.next = after + after.prev = tail + after.next = nil + replace = process(namespace,attribute,before,attr) + replace = replace.next + replace.prev = nil + after.prev.next = nil + disc.replace = replace + free_node(after) + free_node(before) + else + if prv and prv.id == glyph and prv.font == lastfont then + local prevchar, lastchar = prv.char, start.char + local kerns = chardata[lastfont][prevchar].kerns + local kern = kerns and kerns[lastchar] or 0 + krn = scale(kern+quaddata[lastfont],krn) + else + krn = scale(quaddata[lastfont],krn) + end + disc.replace = make_kern_node(krn) + end + end + end + elseif id == glue and start.subtype == 0 then + local s = start.spec + local w = s.width + if w > 0 then + local width, stretch, shrink = w+2*scale(w,krn), s.stretch, s.shrink + start.spec = make_glue_spec(width,scale(stretch,width/w),scale(shrink,width/w)) + -- local width, stretch, shrink = w+2*w*krn, s.stretch, s.shrink + -- start.spec = make_glue_spec(width,stretch*width/w,shrink*width/w)) + done = true + end + elseif false and id == kern and start.subtype == 0 then -- handle with glyphs + local sk = start.kern + if sk > 0 then + -- start.kern = scale(sk,krn) + start.kern = sk*krn + done = true + end + elseif lastfont and (id == hlist or id == vlist) then -- todo: lookahead + if start.prev then + insert_node_before(head,start,make_kern_node(scale(quaddata[lastfont],krn))) + done = true + end + if start.next then + insert_node_after(head,start,make_kern_node(scale(quaddata[lastfont],krn))) + done = true + end + end + end + end + if start then + start = start.next + end + end + return head, done +end + +kerns.process = function(namespace,attribute,head) + return process(namespace,attribute,head) -- no direct map, because else fourth argument is tail == true +end + +lists.handle_kerning = nodes.install_attribute_handler { + name = "kern", + namespace = kerns, + processor = kerns.process, +} + +function kerns.enable() + tasks.enableaction("processors","lists.handle_kerning") +end |