使用 lua 代码为每个字母设置边界框（后续问题）

Question

代码中有一个错误，导致 Lua 循环中断。我尝试过即使没有下一个指针也进行r赋值。修复方法是保护赋值：head.next.prevhead

if head.next then
     head.next.prev = r
end

所以代码是：

%% thesis.tex 2014/04/11
% Source: https://math.berkeley.edu/~vojta/thesis/
% Integrated into one single file, extended using topskip's luaCharBox-code
%
\documentclass{ucbthesis}
\usepackage{luacode,luatexbase,microtype,blindtext}
\begin{luacode*}
local GLYPH_ID = node.id("glyph")

-- head is a linked list (next/prev entries pointing to the next node)
-- parent it the surrounding h/vbox
function showcharbox(head,parent)
    while head do
        if head.id == 0 or head.id == 1 then
            -- a hbox/vbox
            showcharbox(head.list,head)
        elseif head.id == GLYPH_ID then
            r = node.new("rule")
            r.width  = head.width
            r.height = head.height
            r.depth  = head.depth

            -- replace the glyph by
            -- the rule by changing the
            -- pointers of the next/prev
            -- entries of the rule node
            if head.prev then
                head.prev.next = r
            else
                -- first glyph in a list
                parent.list = r
            end

            if head.next then
              head.next.prev = r
            end

            r.prev = head.prev
            r.next = head.next

            -- now the glyph points to
            -- nowhere and we should remove
            -- it from the memory
            node.free(head)

            head = r
        end
        head = head.next
    end
    return true
end


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

\newtheorem{theorem}{Jibberish}

\begin{document}
\pagestyle{headings}

That's fine until footnote:\footnote{Davidson witting and grammatic.}

\begin{theorem}
    \tolerance=10000\hbadness=10000
    This does not work.
\end{theorem}

That's fine again: Wash, Doff, and Algorithm.

\begin{itemize}
    \item Items work partially.
    \item Salutary.  Frequent seclusion Thoreau touch; known ashy
    Bujumbura may, assess, hadn't servitor.  Wash, Doff, and Algorithm.
\end{itemize}
\end{document}

回答附加问题：我不知道为什么标题没有调用post_linebreak_filter，也许它没有分成几行？！？

您可以使用该包atbegshi来获取页面的完整内容：

\documentclass[a4paper,10pt]{article}
\usepackage{luacode,atbegshi}
\begin{luacode*}
local GLYPH_ID = node.id("glyph")

-- head is a linked list (next/prev entries pointing to the next node)
-- parent it the surrounding h/vbox
function showcharbox(head,parent)
    while head do
        if head.id == 0 or head.id == 1 then
            -- a hbox/vbox
            showcharbox(head.list,head)
        elseif head.id == GLYPH_ID then
            r = node.new("rule")
            r.width  = head.width
            r.height = head.height
            r.depth  = head.depth

            -- replace the glyph by
            -- the rule by changing the
            -- pointers of the next/prev
            -- entries of the rule node
            if head.prev then
                head.prev.next = r
            else
                -- first glyph in a list
                parent.list = r
            end

            if head.next then
              head.next.prev = r
            end

            r.prev = head.prev
            r.next = head.next

            -- now the glyph points to
            -- nowhere and we should remove
            -- it from the memory
            node.free(head)

            head = r
        end
        head = head.next
    end
    return true
end


\end{luacode*}
\AtBeginShipout {\directlua{showcharbox(tex.box["AtBeginShipoutBox"])}}%
\begin{document}

\begin{figure}
\fbox{x}
\caption{Hello World!}
\end{figure}
\end{document}

顺便说一句：请做一个米下次我们再来。文档不需要，microtype也不tikz需要显示问题。甚至blindtext不需要。

Answer 1