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LuaTex 获取“字形”节点的位置

tag-icon • tag-icon luatex tex-core
LuaTex 获取“字形”节点的位置

我试图在生成 pdf 文件时记录字形节点的位置，但调用 pdf.getpos() 函数时总是得到 0 值。我该如何修复它？这是我的代码，输出记录在输出文件“test.txt”中。

\documentclass{article}
\usepackage{luacode,luatexbase}
\usepackage[letterpaper,left=1in,right=1in,top=1in,bottom=1in]{geometry}

\begin{document}
\begin{luacode*}
local GLYPH_ID = node.id("glyph")

function getposition(head)
  while head do
    if head.id == 0 or head.id == 1 then
      getposition(head.list)
    elseif head.id == GLYPH_ID then
      local savepos = node.new("whatsit","save_pos")
      local h,v  =  pdf.getpos()
      file = io.open("test.txt", "a")
      file:write(tostring(h), " ", tostring(v),"\n")
      file:close()
    end
    head = head.next
  end
  return true
end

luatexbase.add_to_callback("post_linebreak_filter",getposition,"getposition")
\end{luacode*}

My \emph{text} should be here and it can be really long so the lines can break but I still need to get position of glyph nodes.

\end{document}

答案1

关注此处的评论https://tex.stackexchange.com/a/591608/249348，答案如下((TeX Live 2021) (format=lualatex 2021.8.18)):

\documentclass{scrbook}

\usepackage{fontspec}
\usepackage{luacode}

\setmainfont{Libertinus Serif}
\begin{luacode}
function PrintPos()
    local x,y = pdf.getpos()
    file = io.open("test.txt", "a")
     file:write(x," ",y,"\string\n")
     file:close()
end
function ProcessList(head)
    for n in node.traverse(head) do
        if node.is_glyph(n) then
            local printpos = node.new("whatsit","late_lua")
            printpos.data = PrintPos
            node.insert_after(head, n, printpos)
        end
        if n.head ~= nil then
            ProcessList(n.head)
        end
    end
end
function PrintCoordinates()
    local soBox = tex.getbox("ShipoutBox")
    ProcessList(soBox)
end
\end{luacode}
\AddToHook{shipout/before}{\directlua{PrintCoordinates()}}

\begin{document}
My \emph{text} should be here and it can be really long so the lines can break but I still need to get position of glyph nodes.
\end{document}

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