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-- Copyright (c) 2022-2023 Thomas Kelkel kelkel@emaileon.de
-- This file may be distributed and/or modified under the
-- conditions of the LaTeX Project Public License, either
-- version 1.3c of this license or (at your option) any later
-- version. The latest version of this license is in
-- http://www.latex-project.org/lppl.txt
-- and version 1.3c or later is part of all distributions of
-- LaTeX version 2009/09/24 or later.
-- Version: 0.3
local ID = node.id
local GLYPH = ID ( "glyph" )
local DISC = ID ( "disc" )
local GLUE = ID ( "glue" )
local KERN = ID ( "kern" )
local WI = ID ( "whatsit" )
local HLIST = ID ( "hlist" )
local VLIST = ID ( "vlist" )
local PDF_LITERAL = table.swapped ( node.whatsits () )["pdf_literal"]
local NEW = node.new
local PREV = node.prev
local NEXT = node.next
local TAIL = node.tail
local INS_B = node.insert_before
local INS_A = node.insert_after
local HAS_GLYPH = node.has_glyph
local T = node.traverse
local T_ID = node.traverse_id
local FLOOR = math.floor
local ABS = math.abs
local ATC = luatexbase.add_to_callback
-----
local on_top = false
local DIR = PREV
local AB = INS_B
local f = 1
function showkerning_on_top ()
on_top = true
DIR = NEXT
AB = INS_A
f = - 1
end
local function round ( num, dec )
return FLOOR ( num * 10^dec + 0.5 ) / 10^dec
end
local function calc_value ( value )
value = round ( value / 65781, 3 )
return value
end
local function find_first_last ( n, node_type, last )
local d = NEXT
if last then
d = PREV
n = TAIL ( n )
end
while true do
if n and n.id == node_type then
return n
end
if d ( n ) then
n = d ( n )
else
return false
end
end
end
local function find_glyph ( n, d )
local kern_value = 0
if d ( n ) then
n = d ( n )
while not ( n.id == GLYPH or n.replace and HAS_GLYPH ( n.replace ) ) do
if not d ( n ) then return false end
if n.id == GLUE then
kern_value = kern_value + n.width
end
n = d ( n )
end
else
return false
end
local return_value = n
if n.id == DISC then
return_value = find_first_last ( n.replace, GLYPH, d == PREV )
for kern_node in T_ID ( KERN, n.replace ) do
kern_value = kern_value + kern_node.kern
end
end
return return_value, n, kern_value
end
local function check_glyph ( n, d, has_prev_next_glyph, prev_next_glyph, insert_prev_next )
local kern_value
if find_glyph ( n, d ) then
prev_next_glyph, insert_prev_next, kern_value = find_glyph ( n, d )
has_prev_next_glyph = true
end
return has_prev_next_glyph, prev_next_glyph, insert_prev_next, kern_value
end
local function get_x_value ( n, x_value )
local exp_fac = 1
if n.expansion_factor then
exp_fac = n.expansion_factor / 1000000 + 1
end
if n.width then
x_value = x_value + calc_value ( n.width ) * exp_fac
elseif n.kern then
x_value = x_value + calc_value ( n.kern ) * exp_fac
end
return x_value
end
local function find_kern ( n, d )
local kern_value = 0
local disc = false
if d ( n ) then
n = d ( n )
while n and not ( n.id == GLYPH or disc ) do
if n.id == KERN then
kern_value = get_x_value ( n, kern_value )
elseif n.replace then
local start_point = n.replace
if d == PREV then
start_point = TAIL ( n.replace )
end
if start_point.id == KERN then
kern_value = get_x_value ( start_point, kern_value )
end
disc = true
end
if d ( n ) then
n = d ( n )
else
break
end
end
if not ( kern_value == 0 ) then
return kern_value
end
end
return false
end
local function make_rule ( head, n, kern_node, current_head, disc_list )
local color = "0 0 0"
local has_prev_glyph = false
local has_next_glyph = false
local prev_glyph = n
local next_glyph = n
local insert_prev = n
local insert_next = n
local insert_point = n
local x_value = 0
local height = 0
local depth = 0
local prev_kern_value = 0
local next_kern_value = 0
local thickness = calc_value ( kern_node.kern )
has_prev_glyph, prev_glyph, insert_prev, prev_kern_value = check_glyph ( n, PREV, has_prev_glyph, prev_glyph, insert_prev )
has_next_glyph, next_glyph, insert_next, next_kern_value = check_glyph ( n, NEXT, has_next_glyph, next_glyph, insert_next )
if disc_list and not ( TAIL ( current_head ) == kern_node ) and not ( current_head == kern_node ) then
has_prev_glyph, prev_glyph, insert_prev, prev_kern_value = check_glyph ( kern_node, PREV, has_prev_glyph, kern_node, kern_node )
has_next_glyph, next_glyph, insert_next, next_kern_value = check_glyph ( kern_node, NEXT, has_next_glyph, kern_node, kern_node )
end
if not on_top and has_prev_glyph then
insert_point = insert_prev
x_value = get_x_value ( prev_glyph, x_value )
x_value = x_value + calc_value ( prev_kern_value )
if disc_list and HAS_GLYPH ( current_head ) and TAIL ( current_head ) == kern_node then
for some_node in T ( current_head ) do
if some_node == TAIL ( current_head ) then break end
x_value = get_x_value ( some_node, x_value )
end
end
elseif on_top then
insert_point = insert_next
if has_next_glyph then
x_value = get_x_value ( next_glyph, x_value )
x_value = x_value + calc_value ( next_kern_value )
end
if disc_list and HAS_GLYPH ( current_head ) and current_head == kern_node then
local kern_counter = 0
for some_node in T ( current_head ) do
if some_node.id == KERN then
kern_counter = kern_counter + 1
end
if not ( some_node == current_head ) then
x_value = get_x_value ( some_node, x_value )
end
end
if find_kern ( n, NEXT ) then
x_value = x_value + find_kern ( n, NEXT )
end
end
end
if disc_list and HAS_GLYPH ( current_head ) then
if TAIL ( current_head ) == kern_node then
has_prev_glyph = false
has_prev_glyph, prev_glyph = check_glyph ( kern_node, PREV, has_prev_glyph, prev_glyph, insert_prev )
end
if current_head == kern_node then
has_next_glyph = false
has_next_glyph, next_glyph = check_glyph ( kern_node, NEXT, has_next_glyph, next_glyph, insert_next )
end
end
if has_prev_glyph then
height = calc_value ( prev_glyph.height )
depth = calc_value ( prev_glyph.depth )
if has_next_glyph then
if next_glyph.height > prev_glyph.height then height = calc_value ( next_glyph.height ) end
if next_glyph.depth > prev_glyph.depth then depth = calc_value ( next_glyph.depth ) end
end
elseif has_next_glyph then
height = calc_value ( next_glyph.height )
depth = calc_value ( next_glyph.depth )
end
if find_kern ( n, PREV ) then
thickness = thickness + find_kern ( n, PREV )
end
if thickness ~= 0 and thickness > calc_value ( tex.hsize ) * - 1 then
if thickness > 0 then
color = "0 1 0"
else
color = "1 0 0"
end
if disc_list and not ( TAIL ( current_head ) == kern_node ) and not ( current_head == kern_node ) then
current_head = AB ( current_head, insert_point, NEW ( WI, PDF_LITERAL ) )
else
head = AB ( head, insert_point, NEW ( WI, PDF_LITERAL ) )
end
x_value = ( x_value + calc_value ( kern_node.expansion_factor ) + thickness * 0.5 ) * f
DIR ( insert_point ).mode = 0
DIR ( insert_point ).data = "q " .. ABS ( thickness ) .. " w " .. x_value .. " " .. - depth .. " m " .. x_value .. " " .. height .. " l " .. color .. " RG S Q"
end
return head, current_head
end
local function show_kerns ( head )
for n in T ( head ) do
if n.id == HLIST or n.id == VLIST then
n.head = show_kerns ( n.head )
elseif n.id == KERN and not find_kern ( n, NEXT ) then
head = make_rule ( head, n, n, head, false )
elseif n.replace then
local REPLACE = n.replace
for kern_node in T_ID ( KERN, REPLACE ) do
if not find_kern ( kern_node, NEXT ) then
head, REPLACE = make_rule ( head , n, kern_node, REPLACE, true )
end
end
n.replace = REPLACE
end
end
return head
end
ATC ( "post_linebreak_filter", show_kerns, "show kerns in postline" )
ATC ( "hpack_filter", show_kerns, "show kerns in hpack" )
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