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if not modules then modules = { } end modules ['typo-par'] = {
version = 1.001,
comment = "companion to typo-par.mkiv",
author = "Hans Hagen, PRAGMA-ADE, Hasselt NL",
copyright = "PRAGMA ADE / ConTeXt Development Team",
license = "see context related readme files"
}
-- A playground for experiments.
local utfbyte = utf.byte
local utfchar = utf.char
local trace_paragraphs = false trackers.register("typesetters.paragraphs", function(v) trace_paragraphs = v end)
local trace_dropper = false trackers.register("typesetters.paragraphs.dropper",function(v) trace_dropper = v end)
local report_paragraphs = logs.reporter("nodes","paragraphs")
local report_dropper = logs.reporter("nodes","dropped")
typesetters.paragraphs = typesetters.paragraphs or { }
local paragraphs = typesetters.paragraphs
local nodecodes = nodes.nodecodes
local whatsitcodes = nodes.whatsitcodes
local tasks = nodes.tasks
local variables = interfaces.variables
local texattribute = tex.attribute
local unsetvalue = attributes.unsetvalue
local has_attribute = node.has_attribute
local set_attribute = node.set_attribute
local glyph_code = nodecodes.glyph
local hlist_code = nodecodes.hlist
local kern_node = nodecodes.kern
local whatsit_code = nodecodes.whatsit
local localpar_code = whatsitcodes.localpar
local a_paragraph = attributes.private("paragraphspecial")
local a_color = attributes.private('color')
local a_transparency = attributes.private('transparency')
local a_colorspace = attributes.private('colormodel')
local dropper = {
enabled = false,
-- font = 0,
-- n = 0,
-- distance = 0,
-- hoffset = 0,
-- voffset = 0,
}
local droppers = { }
typesetters.paragraphs.droppers = droppers
function droppers.set(specification)
dropper = specification or { }
end
function droppers.freeze()
if dropper.enabled then
dropper.font = font.current()
end
end
-- dropped caps experiment (will be done properly when luatex
-- stores the state in the local par node) .. btw, search still
-- works with dropped caps, as does an export
-- we need a 'par' attribute and in fact for dropped caps we don't need
-- need an attribute ... dropit will become s state counter (or end up
-- in the localpar user data
-- for the moment, each paragraph gets a number as id (attribute) ..problem
-- with nesting .. or anyhow, needed for tagging anyway
-- todo: prevent linebreak .. but normally a dropper ends up atthe top of
-- a page so this has a low priority
local function process(namespace,attribute,head)
local done = false
if head.id == whatsit_code and head.subtype == localpar_code then
-- begin of par
local a = has_attribute(head,attribute)
if a and a > 0 then
if dropper.enabled then
dropper.enabled = false -- dangerous for e.g. nested || in tufte
local first = head.next
if first and first.id == hlist_code then
-- parbox .. needs to be set at 0
first = first.next
end
if first and first.id == glyph_code then
-- if texattribute[a_paragraph] >= 0 then
-- texattribute[a_paragraph] = unsetvalue
-- end
local char = first.char
local prev = first.prev
local next = first.next
-- if prev.id == hlist_code then
-- -- set the width to 0
-- end
if next and next.id == kern_node then
next.kern = 0
end
first.font = dropper.font or first.font
-- can be a helper
local ma = dropper.ma or 0
local ca = dropper.ca
local ta = dropper.ta
if ca and ca > 0 then
set_attribute(first,a_colorspace,ma == 0 and 1 or ma)
set_attribute(first,a_color,ca)
end
if ta and ta > 0 then
set_attribute(first,a_transparency,ta)
end
--
local width = first.width
local height = first.height
local depth = first.depth
local distance = dropper.distance or 0
local voffset = dropper.voffset or 0
local hoffset = dropper.hoffset or 0
first.xoffset = - width - hoffset - distance
first.yoffset = - height - voffset
if true then
-- needed till we can store parindent with localpar
first.prev = nil
first.next = nil
local h = node.hpack(first)
h.width = 0
h.height = 0
h.depth = 0
prev.next = h
next.prev = h
h.next = next
h.prev = prev
end
if dropper.location == variables.margin then
-- okay
else
local lines = tonumber(dropper.n) or 0
if lines == 0 then -- safeguard, not too precise
lines = math.ceil((height+voffset) / tex.baselineskip.width)
end
tex.hangafter = - lines
tex.hangindent = width + distance
end
done = true
end
end
end
end
return head, done
end
local enabled = false
function paragraphs.set(n)
if n == variables.reset or not tonumber(n) or n == 0 then
texattribute[a_paragraph] = unsetvalue
else
if not enabled then
tasks.enableaction("processors","typesetters.paragraphs.handler")
if trace_paragraphs then
report_paragraphs("enabling paragraphs")
end
enabled = true
end
texattribute[a_paragraph] = n
end
end
paragraphs.attribute = a_paragraph
paragraphs.handler = nodes.installattributehandler {
name = "paragraphs",
namespace = paragraphs,
processor = process,
}
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