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if not modules then modules = { } end modules ['luatex-gadgets'] = {
version = 1.001,
comment = "companion to luatex-gadgets.tex",
author = "Hans Hagen, PRAGMA-ADE, Hasselt NL",
copyright = "PRAGMA ADE / ConTeXt Development Team",
license = "see context related readme files"
}
if context then return end
-- This module contains some maybe useful gadgets. More might show up here
-- as side effect of tutorials or articles. Don't use this file in ConTeXt
-- because we often have similar mechanisms already.
gadgets = gadgets or { } -- global namespace
-- marking content for optional removal
local marking = { }
gadgets.marking = marking
local marksignal = 5001 -- will be set in the tex module
local lastmarked = 0
local marked = { }
local local_par = 6
local whatsit_node = 8
function marking.setsignal(n)
marksignal = tonumber(n) or marksignal
end
function marking.mark(str)
local currentmarked = marked[str]
if not currentmarked then
lastmarked = lastmarked + 1
currentmarked = lastmarked
marked[str] = currentmarked
end
tex.setattribute(marksignal,currentmarked)
end
function marking.remove(str)
local attr = marked[str]
if not attr then
return
end
local list = tex.nest[tex.nest.ptr]
if list then
local head = list.head
local tail = list.tail
local last = tail
if last[marksignal] == attr then
local first = last
while true do
local prev = first.prev
if not prev
or prev[marksignal] ~= attr
or (prev.id == whatsit_node and prev.subtype == local_par) then
break
else
first = prev
end
end
if first == head then
list.head = nil
list.tail = nil
else
local prev = first.prev
list.tail = prev
prev.next = nil
end
node.flush_list(first)
end
end
end
-- local imgscan = img.scan
--
-- local valid = {
-- ["png"] = "^" .. string.char(0x89,0x50,0x4E,0x47,0x0D,0x0A,0x1A,0x0A),
-- ["jpg"] = "^" .. string.char(0xFF,0xD8,0xFF),
-- ["jp2"] = "^" .. string.char(0x00,0x00,0x00,0x0C,0x6A,0x50,0x20,0x20,0x0D,0x0A),
-- ["pdf"] = "^" .. ".-%%PDF",
-- }
--
-- function img.scan(t)
-- if t and t.filename then
-- local f = io.open(t.filename,"rb")
-- if f then
-- local d = f:read(4096)
-- for k, v in next,valid do
-- if string.find(d,v) then
-- f:close() -- be nice
-- return imgscan(t)
-- end
-- end
-- f:close() -- be nice
-- end
-- end
-- end
--
-- print(img.scan({filename = "hacker1b.tif"}))
-- print(img.scan({filename = "cow.pdf"}))
-- print(img.scan({filename = "mill.png"}))
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