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if not modules then modules = { } end modules ['lpdf-tag'] = {
version = 1.001,
comment = "companion to lpdf-tag.mkiv",
author = "Hans Hagen, PRAGMA-ADE, Hasselt NL",
copyright = "PRAGMA ADE / ConTeXt Development Team",
license = "see context related readme files"
}
local format, match, concat = string.format, string.match, table.concat
local lpegmatch = lpeg.match
local utfchar = utf.char
local trace_tags = false trackers.register("structure.tags", function(v) trace_tags = v end)
local report_tags = logs.new("tags")
local pdfdictionary = lpdf.dictionary
local pdfarray = lpdf.array
local pdfboolean = lpdf.boolean
local pdfconstant = lpdf.constant
local pdfreference = lpdf.reference
local pdfunicode = lpdf.unicode
local pdfstring = lpdf.string
local pdfflushobject = lpdf.flushobject
local pdfreserveobject = lpdf.reserveobject
local pdfpagereference = lpdf.pagereference
local new_pdfliteral = nodes.pdfliteral
local hlist = node.id("hlist")
local vlist = node.id("vlist")
local glyph = node.id("glyph")
local glue = node.id("glue")
local disc = node.id("disc")
local whatsit = node.id("whatsit")
local a_tagged = attributes.private('tagged')
local a_image = attributes.private('image')
local has_attribute, set_attribute, traverse_nodes, traverse_id = node.has_attribute, node.set_attribute, node.traverse, node.traverse_id
local tosequence = nodes.tosequence
local copy_node, slide_nodelist = node.copy, node.slide
local structure_stack = { }
local structure_kids = pdfarray()
local structure_ref = pdfreserveobject()
local parent_ref = pdfreserveobject()
local root = { pref = pdfreference(structure_ref), kids = structure_kids }
local tree = { }
local elements = { }
local names = pdfarray()
local taglist = { } -- set later
local colonsplitter = lpeg.splitat(":")
local dashsplitter = lpeg.splitat("-")
local add_ids = false -- true
local mapping = {
document = "Div",
division = "Div",
paragraph = "P",
construct = "Span",
structure = "Sect",
structuretitle = "H",
structurenumber = "H",
structurecontent = "Div",
itemgroup = "L",
item = "Li",
itemtag = "Lbl",
itemcontent = "LBody",
description = "Li",
descriptiontag = "Lbl",
descriptioncontent = "LBody",
verbatimblock = "Code",
verbatim = "Code",
register = "Div",
registersection = "Div",
registertag = "Span",
registerentries = "Div",
registerentry = "Span",
registersee = "Span",
registerpages = "Span",
registerpage = "Span",
table = "Table",
tablerow = "TR",
tablecell = "TD",
tabulate = "Table",
tabulaterow = "TR",
tabulatecell = "TD",
list = "TOC",
listitem = "TOCI",
listtag = "Lbl",
listcontent = "P",
listdata = "P",
listpage = "Reference",
delimitedblock = "BlockQuote",
delimited = "Quote",
subsentence = "Span",
float = "Div",
floatcaption = "Caption",
floattag = "Span",
floattext = "Span",
floatcontent = "P",
image = "P",
mpgraphic = "P",
formulaset = "Div",
formula = "Div",
formulatag = "Span",
formulacontent = "P",
subformula = "Div",
link = "Link",
math = "Div",
mn = "Span",
mi = "Span",
mo = "Span",
ms = "Span",
mrow = "Span",
msubsup = "Span",
msub = "Span",
msup = "Span",
merror = "Span",
munderover = "Span",
munder = "Span",
mover = "Span",
mtext = "Span",
mfrac = "Span",
mroot = "Span",
msqrt = "Span",
}
local usedmapping = { }
local usedlabels = { }
function backends.codeinjections.mapping()
return mapping -- future versions may provide a copy
end
function backends.codeinjections.maptag(original,target)
mapping[original] = target
end
local function finishstructure()
if #structure_kids > 0 then
local nums = pdfarray()
for i=1,#tree do
nums[#nums+1] = i-1
nums[#nums+1] = pdfreference(pdfflushobject(tree[i]))
end
local parenttree = pdfdictionary {
Nums = nums
}
-- we need to split names into smaller parts (e.g. alphabetic or so)
if add_ids then
local kids = pdfdictionary {
Limits = pdfarray { names[1], names[#names-1] },
Names = names,
}
local idtree = pdfdictionary {
Kids = pdfarray { pdfreference(pdfflushobject(kids)) },
}
end
--
local rolemap = pdfdictionary()
for k, v in next, usedmapping do
k = usedlabels[k] or k
rolemap[k] = pdfconstant(mapping[k] or "Span") -- or "Div"
end
local structuretree = pdfdictionary {
Type = pdfconstant("StructTreeRoot"),
K = pdfreference(pdfflushobject(structure_kids)),
ParentTree = pdfreference(pdfflushobject(parent_ref,parenttree)),
IDTree = (add_ids and pdfreference(pdfflushobject(idtree))) or nil,
RoleMap = rolemap,
}
pdfflushobject(structure_ref,structuretree)
lpdf.addtocatalog("StructTreeRoot",pdfreference(structure_ref))
--
local markinfo = pdfdictionary {
Marked = pdfboolean(true),
-- UserProperties = pdfboolean(true),
-- Suspects = pdfboolean(true),
}
lpdf.addtocatalog("MarkInfo",pdfreference(pdfflushobject(markinfo)))
--
for fulltag, element in next, elements do
pdfflushobject(element.knum,element.kids)
end
end
end
lpdf.registerdocumentfinalizer(finishstructure,"document structure")
local index, pageref, pagenum, list = 0, nil, 0, nil
local pdf_mcr = pdfconstant("MCR")
local pdf_struct_element = pdfconstant("StructElem")
local function initializepage()
index = 0
pagenum = tex.count.realpageno
pageref = pdfreference(pdfpagereference(pagenum))
list = pdfarray()
tree[pagenum] = list -- we can flush after done, todo
end
local function finishpage()
-- flush what can be flushed
lpdf.addtopageattributes("StructParents",pagenum-1)
end
-- here we can flush and free elements that are finished
local function makeelement(fulltag,parent)
local tag, n = lpegmatch(dashsplitter,fulltag)
local tg, detail = lpegmatch(colonsplitter,tag)
local k, r = pdfarray(), pdfreserveobject()
usedmapping[tg] = true
tg = usedlabels[tg] or tg
local d = pdfdictionary {
Type = pdf_struct_element,
S = pdfconstant(tg),
ID = (add_ids and fulltag) or nil,
T = detail and detail or nil,
P = parent.pref,
Pg = pageref,
K = pdfreference(r),
--~ Alt = " Who cares ",
--~ ActualText = " Hi Hans ",
}
local s = pdfreference(pdfflushobject(d))
if add_ids then
names[#names+1] = fulltag
names[#names+1] = s
end
local kids = parent.kids
kids[#kids+1] = s
elements[fulltag] = { tag = tag, pref = s, kids = k, knum = r, pnum = pagenum }
end
local function makecontent(parent,start,stop,slist,id)
local tag, kids = parent.tag, parent.kids
local last = index
if id == "image" then
local d = pdfdictionary {
Type = pdf_mcr,
Pg = pageref,
MCID = last,
Alt = "image",
}
kids[#kids+1] = d
elseif pagenum == parent.pnum then
kids[#kids+1] = last
else
local d = pdfdictionary {
Type = pdf_mcr,
Pg = pageref,
MCID = last,
}
-- kids[#kids+1] = pdfreference(pdfflushobject(d))
kids[#kids+1] = d
end
--
local bliteral = new_pdfliteral(format("/%s <</MCID %s>>BDC",tag,last))
local prev = start.prev
if prev then
prev.next, bliteral.prev = bliteral, prev
end
start.prev, bliteral.next = bliteral, start
if slist and slist.list == start then
slist.list = bliteral
elseif not prev then
report_tags("this can't happen: injection in front of nothing")
end
--
local eliteral = new_pdfliteral("EMC")
local next = stop.next
if next then
next.prev, eliteral.next = eliteral, next
end
stop.next, eliteral.prev = eliteral, stop
--
index = index + 1
list[index] = parent.pref
return bliteral, eliteral
end
-- -- --
local level, last, ranges, range = 0, nil, { }, { }
local function collectranges(head,list)
for n in traverse_nodes(head) do
local id = n.id -- 14: image, 8: literal (mp)
if id == glyph then
local at = has_attribute(n,a_tagged)
if not at then
range = nil
elseif last ~= at then
range = { at, "glyph", n, n, list } -- attr id start stop list
ranges[#ranges+1] = range
last = at
elseif range then
range[4] = n -- stop
end
elseif id == hlist or id == vlist then
local at = has_attribute(n,a_image)
if at then
local at = has_attribute(n,a_tagged)
if not at then
range = nil
else
ranges[#ranges+1] = { at, "image", n, n, list } -- attr id start stop list
end
last = nil
else
slide_nodelist(n.list) -- temporary hack till math gets slided (tracker item)
collectranges(n.list,n)
end
end
end
end
function backends.nodeinjections.addtags(head)
-- no need to adapt head, as we always operate on lists
level, last, ranges, range = 0, nil, { }, { }
initializepage()
collectranges(head)
if trace_tags then
for i=1,#ranges do
local range = ranges[i]
local attr, id, start, stop = range[1], range[2], range[3], range[4]
local tags = taglist[attr]
if tags then
report_tags("%s => %s : %05i %s",tosequence(start,start),tosequence(stop,stop),attr,concat(tags," "))
end
end
end
for i=1,#ranges do
local range = ranges[i]
local attr, id, start, stop, list = range[1], range[2], range[3], range[4], range[5]
local tags = taglist[attr]
local prev = root
local noftags, tag = #tags, nil
for j=1,noftags do
local tag = tags[j]
if not elements[tag] then
makeelement(tag,prev)
end
prev = elements[tag]
end
local b, e = makecontent(prev,start,stop,list,id)
if start == head then
report_tags("this can't happen: parent list gets tagged")
head = b
end
end
finishpage()
-- can be separate feature
--
-- injectspans(head) -- does to work yet
--
return head, true
end
function backends.codeinjections.enabletags(tg,lb)
taglist = tg
usedlabels = lb
structure.tags.handler = backends.nodeinjections.addtags
tasks.enableaction("shipouts","structure.tags.handler")
tasks.enableaction("shipouts","nodes.accessibility.handler")
tasks.enableaction("math","noads.add_tags")
if trace_tags then
report_tags("enabling structure tags")
end
end
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