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-- Copyright 2012-2023 Patrick Gundlach, patrick@gundla.ch Public repository:
-- https://github.com/pgundlach/lvdebug (issues/pull requests,...) Version: see
-- Makefile
-- Permission is hereby granted, free of charge, to any person obtaining a copy
-- of this software and associated documentation files (the "Software"), to deal
-- in the Software without restriction, including without limitation the rights
-- to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
-- copies of the Software, and to permit persons to whom the Software is
-- furnished to do so, subject to the following conditions:
--
-- The above copyright notice and this permission notice shall be included in
-- all copies or substantial portions of the Software.
--
-- THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-- IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-- FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-- AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-- LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-- OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
-- SOFTWARE.
-- There are 65782 scaled points in a PDF point
-- Therefore we need to divide all TeX lengths by
-- this amount to get the PDF points.
local number_sp_in_a_pdf_point = 65782
-- The idea is the following: at page shipout, all elements on a page are fixed.
-- TeX creates an intermediate data structure before putting that into the PDF
-- We can "intercept" that data structure and add pdf_literal (whatist) nodes,
-- that makes glues, kerns and other items visible by drawing a rule, rectangle
-- or other visual aids. This has no influence on typeset material, because
-- these pdf_literal instructions are only visible to the PDF file (PDF
-- renderer) and have no size themselves.
-- We recursively loop through the contents of boxes and look at the (linear)
-- list of items in that box. We start at the "shipout box".
-- The "algorithm" goes like this:
--
-- head = pointer_to_beginning_of_box_material
-- while head is not nil
-- if this_item_is_a_box
-- recurse_into_contents
-- draw a rectangle around the contents
-- elseif this_item_is_a_glue
-- draw a rule that has the length of that glue
-- elseif this_item_is_a_kern
-- draw a rectangle with width of that kern
-- ...
-- end
-- move pointer to the next item in the list
-- -- the pointer is "nil" if there is no next item
-- end
local HLIST = node.id("hlist")
local VLIST = node.id("vlist")
local RULE = node.id("rule")
local DIR = node.id("dir")
local DISC = node.id("disc")
local GLUE = node.id("glue")
local KERN = node.id("kern")
local PENALTY = node.id("penalty")
local function math_round(num, idp)
if idp and idp>0 then
local mult = 10^idp
return math.floor(num * mult + 0.5) / mult
end
return math.floor(num + 0.5)
end
local curdir = {}
local show_page_elements
function show_page_elements(parent)
local head = parent.list
while head do
local has_dir = false
if head.dir == "TLT" then
table.insert(curdir,"ltr")
has_dir=true
elseif head.dir == "TRT" then
table.insert(curdir,"rtl") has_dir=true
end
if head.id == HLIST or head.id == VLIST then
local rule_width = 0.1
local wd = math_round(head.width / number_sp_in_a_pdf_point - rule_width ,2)
local ht = math_round((head.height + head.depth) / number_sp_in_a_pdf_point - rule_width ,2)
local dp = math_round(head.depth / number_sp_in_a_pdf_point - rule_width / 2 ,2)
-- recurse into the contents of the box
show_page_elements(head)
local rectangle = node.new("whatsit","pdf_literal")
if curdir[#curdir] == "rtl" then wd = wd * -1 end
if head.id == HLIST then -- hbox
rectangle.data = string.format("q 0.5 G %g w %g %g %g %g re s Q", rule_width, -rule_width / 2, -dp, wd, ht)
else
rectangle.data = string.format("q 0.1 G %g w %g %g %g %g re s Q", rule_width, -rule_width / 2, 0, wd, -ht)
end
head.list = node.insert_before(head.list,head.list,rectangle)
elseif head.id == RULE then
local show_rule = node.new("whatsit","pdf_literal")
if head.width == -1073741824 or head.height == -1073741824 or head.depth == -1073741824 then
-- ignore for now -- these rules are stretchable
else
local dp = math_round( head.depth / number_sp_in_a_pdf_point ,2)
local ht = math_round( head.height / number_sp_in_a_pdf_point ,2)
show_rule.data = string.format("q 1 0 0 RG 1 0 0 rg 0.4 w 0 %g m 0 %g l S Q",-dp,ht)
end
parent.list = node.insert_before(parent.list,head,show_rule)
elseif head.id == DISC then
local hyphen_marker = node.new("whatsit","pdf_literal")
hyphen_marker.data = "q 0 0 1 RG 0.3 w 0 -1 m 0 0 l S Q"
parent.list = node.insert_before(parent.list,head,hyphen_marker)
elseif head.id == DIR then
local mode = string.sub(head.dir,1,1)
local texdir = string.sub(head.dir,2,4)
local ldir
if texdir == "TLT" then ldir = "ltr" else ldir = "rtl" end
if mode == "+" then
table.insert(curdir,ldir)
elseif mode == "-" then
local x = table.remove(curdir)
if x ~= ldir then
print(string.format("paragraph direction incorrect, found %s, expected %s",ldir,x))
end
end
elseif head.id == GLUE then
local head_spec = head.spec
if not head_spec then
head_spec = head
end
local wd = head_spec.width
local color = "0.5 G"
if parent.glue_sign == 1 and parent.glue_order == head_spec.stretch_order then
wd = wd + parent.glue_set * head_spec.stretch
color = "0 0 1 RG"
elseif parent.glue_sign == 2 and parent.glue_order == head_spec.shrink_order then
wd = wd - parent.glue_set * head_spec.shrink
color = "1 0 1 RG"
end
local pdfstring = node.new("whatsit","pdf_literal")
local wd_bp = math_round(wd / number_sp_in_a_pdf_point,2)
if curdir[#curdir] == "rtl" then wd_bp = wd_bp * -1 end
if parent.id == HLIST then
pdfstring.data = string.format("q %s [0.2] 0 d 0.5 w 0 0 m %g 0 l S Q", color, wd_bp)
else -- vlist
pdfstring.data = string.format("q 0.1 G 0.1 w -0.5 0 m 0.5 0 l -0.5 %g m 0.5 %g l S [0.2] 0 d 0.5 w 0.25 0 m 0.25 %g l S Q",-wd_bp,-wd_bp,-wd_bp)
end
parent.list = node.insert_before(parent.list,head,pdfstring)
elseif head.id == KERN then
local rectangle = node.new("whatsit","pdf_literal")
local color = "1 1 0 rg"
if head.kern < 0 then color = "1 0 0 rg" end
local k = math_round(head.kern / number_sp_in_a_pdf_point,2)
if parent.id == HLIST then
rectangle.data = string.format("q %s 0 w 0 0 %g 1 re B Q",color, k )
else
rectangle.data = string.format("q %s 0 w 0 0 1 %g re B Q",color, -k )
end
parent.list = node.insert_before(parent.list,head,rectangle)
elseif head.id == PENALTY then
local color = "1 g"
local rectangle = node.new("whatsit","pdf_literal")
if head.penalty < 10000 then
color = string.format("%d g", 1 - math.floor(head.penalty / 10000))
end
rectangle.data = string.format("q %s 0 w 0 0 1 1 re B Q",color)
parent.list = node.insert_before(parent.list,head,rectangle)
end
if has_dir then
table.remove(curdir)
end
head = head.next
end
return true
end
return {
show_page_elements = show_page_elements
}
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