luametalatex/luametalatex-pdf-outline.lua

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local function add_outline(outline, title, action, level, open, attr)
local entry = {title = title, action = action, attr = attr, open = open, level = level}
-- Now find the right nesting level. We have to deal with non-continuous
-- levels, so we search the last entry which still had a smaller level
-- and append under that
local parent
repeat
parent = outline
outline = outline[#outline]
until not outline or outline.level >= level
parent[#parent + 1] = entry
end
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local function add_legacy(outline, title, action, count, attr)
local state = outline.legacy
if not state then
state = {}
outline.legacy = state
end
local level = #state
if level ~= 0 then
state[level] = state[level] - 1
end
local open
if count and count ~= 0 then
open = count > 0
if not open then
count = -count
end
state[level+1] = count
else
open = false -- Doesn't matter without children
while state[#state] == 0 do
state[#state] = nil
end
end
return outline:add(title, action, level, open, attr)
end
local function assign_objnum(pdf, outline)
local objnum = pdf:getobj()
outline.objnum = objnum
local cur
for i=1,#outline do
local prev = cur
cur = outline[i]
cur.parent = objnum
assign_objnum(pdf, cur)
if prev then
cur.prev = prev.objnum
prev.next = cur.objnum
end
end
if outline[1] then
outline.first, outline.last = outline[1].objnum, outline[#outline].objnum
end
end
local function get_count(pdf, outline)
local count = 0
for i=1,#outline do
local child = outline[i]
local sub = get_count(pdf, child)
local open = child.open
child.count = sub ~= 0 and (open and sub or -sub) or nil
count = count + 1 + (open and sub or 0)
end
return count
end
local function write_objects(pdf, outline)
local content = "<<"
local title = outline.title
if title then
content = string.format("%s/Title%s", content, title)
end
local parent = outline.parent
if parent then
content = string.format("%s/Parent %i 0 R", content, parent)
end
local prev = outline.prev
if prev then
content = string.format("%s/Prev %i 0 R", content, prev)
end
local next = outline.next
if next then
content = string.format("%s/Next %i 0 R", content, next)
end
local first = outline.first
if first then
content = string.format("%s/First %i 0 R", content, first)
end
local last = outline.last
if last then
content = string.format("%s/Last %i 0 R", content, last)
end
local action = outline.action
if action then
content = string.format("%s/A %i 0 R", content, action)
end
local count = outline.count
if count then
content = string.format("%s/Count %i", content, count)
end
content = content .. (outline.attr or '') .. ">>"
pdf:indirect(outline.objnum, content)
for i=1,#outline do
write_objects(pdf, outline[i])
end
end
local function write_outline(outline, pdf)
assign_objnum(pdf, outline)
local count = get_count(pdf, outline)
outline.count = count == #outline and count or nil
write_objects(pdf, outline)
return outline.objnum
end
local meta = {__index = {
write = write_outline,
add = add_outline,
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add_legacy = add_legacy,
}}
return function()
return setmetatable({}, meta)
end