环境开始和结束时的 Tikzmark

Question

警告： 该代码尚未经过非常广泛的测试，并且在更复杂的情况下可能无法工作。

复杂的部分是将一些代码放在段落的开头。这\everypar就是设计要做，但是它会被许多其他东西覆盖和破坏，因此尝试使用它注定会失败。

幸运的是，LaTeX3 团队有一个可以解决这个问题的软件包，这是我从https://tex.stackexchange.com/a/326947/86，那就是l3galley。这个答案是 2016 年的，但我刚刚尝试过，它在你的用例上效果很好。

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{tikzmark}
\usepackage{tikzpagenodes}
\usepackage{lipsum}

\usepackage{xparse}
\usepackage{l3galley}

\NewDocumentCommand\OutlineParagraph { m }
{
  \tikz[overlay,remember picture] \draw
  ([yshift=\baselineskip]{{pic cs:begin-#1}-|current page text area.west}) -- 
  ([yshift=\baselineskip]{{pic cs:begin-#1}-|current page text area.east});
  \tikz[overlay,remember picture] \draw
  ({{pic cs:end-#1}-|current page text area.west}) -- 
  ({{pic cs:end-#1}-|current page text area.east});
}

\ExplSyntaxOn
\tl_new:N \g_splicer_saved_tl
\NewDocumentEnvironment{myenv}{ m }
{
  \OutlineParagraph{#1}
  \group_begin:
  \tl_set:Nn \l_splicer_name_tl {#1}
  \tl_gset:NV \g_splicer_saved_tl \g_galley_par_begin_hook_tl
  \tl_gput_right:Nn \g_galley_par_begin_hook_tl
  {
    \pgfmark{begin-#1}
  }
}
{
  \pgfmark{end-\tl_use:N \l_splicer_name_tl}
  \tl_gset:NV \g_galley_par_begin_hook_tl \g_splicer_saved_tl
  \group_end:
}
\ExplSyntaxOff

\begin{document}

\tikz[overlay,remember picture] \filldraw[red]
(pic cs:begin-nolist) circle(2pt) -- (pic cs:end-nolist) circle(2pt);

\begin{myenv}{nolist}
\lipsum[1]
\end{myenv}


\begin{myenv}{list}
\begin{itemize}
\item \lipsum[1]
\end{itemize}
\end{myenv}

\tikz[overlay,remember picture] \filldraw[blue]
(pic cs:begin-list) circle(2pt) -- (pic cs:end-list) circle(2pt);

\end{document}

得出的结果为：

现在，这已经有几个问题了。你会注意到，我把\tikz绘制红色圆圈的命令移到了前环境。这是因为，我猜，\g_galley_par_begin_hook_tl执行了几次，但实际上只有一个被排版。这导致出现这种情况，即有多个 tikzmark定义具有相同的名称，但只有一个写入辅助文件。在文档中定义 tikzmark 之前，辅助文件中的那个获胜（通常是您想要的那个），但在定义之后，最后声明的那个获胜。我有一个解决这个问题的解决方法\tikzmarknode，但我需要调查一下，看看处理这个问题的正确方法是什么\tikzmark。对于在段落开头和结尾绘制的线条，这不是问题，因为它们是在文档中定义 tikzmark 之前绘制的，所以它们使用辅助文件中的定义。

更新 2021-03-03

这是更新。它使用l3galley代码在环境中标记段落，然后使用 tikzmark 别名功能选择这些标记中的第一个和最后一个，并使用给定的名称保存它们。（注意：我稍微更新了别名代码，以便从一开始就可以使用别名，就像真正的 tikzmark 一样；不过，我不认为这在本版本的代码中使用。）

我在实际标记代码以及将其放在何处方面遇到了问题，因为即使有选项overlay，TikZ 图片也会创建一个框，如果它出现在错误的位置，则会导致问题，因此我添加了将其放在页脚中的代码。为了确保执行正确的代码，我使用 tikzmark 包中的测试来查看给定的 tikzmark 是否在给定的页面上。

\documentclass{article}
%\url{https://tex.stackexchange.com/q/585759/86}
\usepackage{tikz}
\usetikzlibrary{tikzmark}
\usepackage{tikzpagenodes}
\usepackage{lipsum}

\usepackage{xparse}
\usepackage{l3galley}


% These are the commands that will mark the start and end of the paragraphs
\NewDocumentCommand\MarkParagraphStart { O{red} m m }
{%
  \tikz[overlay,remember picture] {
    \draw[#1]
    (
    [yshift=#2]
    {{pic cs:#3 start}-|current page text area.west}) -- 
    (
    [yshift=#2]
    {{pic cs:#3 start}-|current page text area.east})
  }%
}
\NewDocumentCommand\MarkParagraphEnd { O{blue,dashed,ultra thick} m m }
{%
  \tikz[overlay,remember picture] {
    \draw[#1]
    (
    [yshift=#2]
    {{pic cs:#3 end}-|current page text area.west}) -- 
    (
    [yshift=#2]
    {{pic cs:#3 end}-|current page text area.east})
  }%
}

\ExplSyntaxOn

% Boolean to control whether we are marking paragraphs
\bool_new:N \g_tikzmark_paragraphs_bool
% Count to keep track of paragraphs
\int_new:N \g_tikzmark_paragraph_count_int

% Installs the hooks to possibly mark the start of paragraphs
\tl_gput_right:Nn \g_galley_par_begin_hook_tl
{
  % Are we marking paragraphs?
  \bool_if:NT \g_tikzmark_paragraphs_bool
  {
    % Increment the counter
    \int_gincr:N \g_tikzmark_paragraph_count_int
    % Mark this place
    \pgfmark{paragraph~start~\int_use:N \g_tikzmark_paragraph_count_int}
  }
}
% Installs the hooks to possibly mark the end of paragraphs
\tl_gput_right:Nn \g_galley_par_end_hook_tl
{
  % Are we marking paragraphs?
  \bool_if:NT \g_tikzmark_paragraphs_bool
  {
    % Mark this place
    \pgfmark{paragraph~end~\int_use:N \g_tikzmark_paragraph_count_int}
  }
}

% We do the actual drawing in the footer, this prop will contain a list of
% commands to execute.  To decide which commands, we associate each one
% with a tikzmark.  If the tikzmark is on the current page, the command
% is executed and deleted.
\prop_new:N \g_tikzmark_actions_prop

% This is the command that possibly executes the code
\cs_new:Npn \tikzmark_process_prop:
{
  \prop_map_inline:Nn \g_tikzmark_actions_prop
  {
    \iftikzmarkoncurrentpage{##1}%
    ##2
    \prop_gremove:Nn \g_tikzmark_actions_prop {##1}
    \fi
  }
}

% Install the processing commands in the footer
\tl_gput_right:cn {@oddfoot}
{
  \tikzmark_process_prop:
}
\tl_gput_right:cn {@evenfoot}
{
  \tikzmark_process_prop:
}

% The value of \baselineskip needs to be fixed at the invocation time rather
% than execution time.  Fortunately, LaTeX3 is adept at handling expansion
% so we wrap the code to install the marks in LaTeX3 functions.
\cs_new:Npn \tikzmark_paragraph_start:nnn #1#2#3
{
  \prop_gput:Nnn \g_tikzmark_actions_prop {#1} {
    \MarkParagraphStart {#2}{#3}
  }
}
\cs_new:Npn \tikzmark_paragraph_end:nnn #1#2#3
{
  \prop_gput:Nnn \g_tikzmark_actions_prop {#1} {
    \MarkParagraphEnd {#2}{#3}
  }
}

\cs_generate_variant:Nn \tikzmark_paragraph_start:nnn {nVn}

% We don't use this command, but it demonstrates how to make a user
% command to draw things using tikzmarks 
\NewDocumentCommand \TikzmarkExecute { m m }
{
  \prop_gput:Nnn \g_tikzmark_actions_prop {#1} {#2}
}

% Here's the environment to mark paragraphs
\NewDocumentEnvironment{MarkSection}{ m }
{
  % Set the boolean for marking the paragraphs
  \bool_gset_true:N \g_tikzmark_paragraphs_bool
  % Alias the mark at the start of the first paragraph
  \tikzmarkalias{#1~start}{paragraph~start~\int_eval:n { \g_tikzmark_paragraph_count_int +1 }}
  % Install the code to draw the marks at the start and end
  \tikzmark_paragraph_start:nVn {#1~start} \baselineskip {#1}
  \tikzmark_paragraph_end:nnn {#1~end} {-2pt} {#1}
}
{
  % If we're in horizontal mode when the environment ends then
  % we want to exit it to ensure that the end of the last paragraph
  % is marked
  \ifhmode
  \par
  \fi
  % Stop marking paragraphs
  \bool_gset_false:N \g_tikzmark_paragraphs_bool
  % Alias the end of the last paragraph
  \tikzmarkalias{#1~end}{paragraph~end~\int_use:N \g_tikzmark_paragraph_count_int}
}

\ExplSyntaxOff


\begin{document}

\begin{MarkSection}{no list}
\lipsum[1-4]
\end{MarkSection}

\begin{MarkSection}{list}
\begin{itemize}
\item \lipsum[1]
\item \lipsum[2]
\item \lipsum[3]
\item \lipsum[4]
\end{itemize}
\end{MarkSection}

\end{document}

结果是这样的：

Answer 1