使用盒子的宽度作为 parshape

Question

我使用 tcolorbox 来生成带框定理，其中标题是一个框，我想根据框的宽度在框标题后面的某个距离处开始定理文本。为此，我使用命令set parshape在第一行上放置缩进。我想使用宏根据框的宽度进行缩进\tcbsetmacrotowidthofnode，这可以计算此宽度（命令\mywidth），但我无法在 parshape 中使用它。请注意，我可以使用此框的高度来放置框架的长度，没有任何问题。

我给出了我使用的文件，其中可以注意到我使用了缩进命令{\hsize-(width("Theorem")+0.666em+10.5mm)}，这是可以接受的，而不是我想要的命令，例如{\hsize-\mywidth}。请注意，当是单位时可以接受此命令\tcbcounter，但当是十分之一时则不能接受。我使用 Xelatex 进行编译。

我的问题当然是：如何使用框宽度以合适的方式缩进我的环境文本？

\documentclass{book}

\usepackage[most]{tcolorbox} %So called package for boxing and so...
    \usetikzlibrary{calc} % for the let-syntax etc
\RequirePackage{tikz}

\makeatletter       %%  MACRO ENABLING USE OF SETCOUNTER FOR TCOLORBOX
\newcommand{\settcbcounter}[2]{%
  \@ifundefined{c@tcb@cnt@#1}{%
    \GenericError{Error}{counter name #1 is no tcb counter }{}{}%
  }{%
    \setcounter{tcb@cnt@#1}{#2}%
  }
}
\makeatother

\newlength\LineW
\setlength\LineW{0.5mm}
\tikzset{
  frameline/.style={
    draw=red!75!black,line width=\LineW
  }
}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   Arabic Commands and fonts
\usepackage{polyglossia}
\setmainlanguage[numerals=maghrib]{arabic}
\setotherlanguage{english}
\setmainfont[Script=Arabic]{Arial}  %%  can use any font
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%


\newcommand{\myboxnode}[1]{%
\node[
   fill=red!5!white, draw=red!75!black, line width=.5pt, 
   below left, minimum height=.1em, 
   align=center,
   font=\bfseries
   ] (tmpbox) at 
     ([xshift=-1mm-0.5\LineW,yshift=-1mm-0.5\LineW]frame.north east)
   {\RL{#1 {\normalsize \thetcbcounter}}}}


\newtcolorbox[auto counter,number within=chapter,
        number freestyle={\noexpand\arabic{\tcbcounter}}]{theo}[1][]{%
        enhanced jigsaw,
        breakable, 
        colback=white,
        opacityframe=0,
        top=2mm, bottom=2mm,
        left=2mm, right=2mm,
        % drawing corners on top and title
        underlay unbroken and first={%
            \myboxnode{Theorem};
            \tcbsetmacrotoheightofnode\HHH{tmpbox}
            % \global\let so it's available outside the underlay unbroken and first
            \global\let\myheight\HHH
            \tcbsetmacrotowidthofnode\BBB{tmpbox}
            \global\let\mywidth\BBB
            % draw top right frame
            \draw [frameline=red]
                  ([shift={(0, -\myheight-2.5mm)}]frame.north east) |- 
                  ([shift={(-\textwidth/4,0)}]frame.north east);
            % draw top left frame
            \draw [frameline=red]
                  ([shift={(0,-\myheight-2.5mm)}]frame.north west) |-
                  ([shift={(\textwidth/4,0)}]frame.north west);
        },
        % if box breaks across pages, draw corners on last part
        underlay unbroken and last={%
            % draw bottom right frame
            \draw [frameline=red]
                  ([shift={(0, \myheight+2.5mm)}]frame.south east) |- 
                  ([shift={(-\textwidth/4,0)}]frame.south east);
            % draw bottom left frame
            \draw [frameline=red]
                  ([yshift=\myheight+2.5mm]frame.south west) |- 
                  ([xshift=\textwidth/4]frame.south west);
        },
        set parshape/.code={%
            % 0.666em is twice the inner sep
            \pgfmathsetlengthmacro{\parwidth}{\hsize-(width("Theorem")+0.666em+10.5mm)}
            \tcbset{
                before upper={\vspace*{.5mm}\parshape 2
                    0pt \parwidth
                    0pt \hsize}
                   }
        },
       set parshape={}
#1}


\begin{document}

\begin{theo}
The\\
First\\
Theorem
\end{theo}

\settcbcounter{theo}{9}

\begin{theo}
 The\\
Tenth\\
Theorem
\end{theo}

\end{document}