创建一个展开为菱形的圆圈运算符

Question 1

这个答案处理 TeX/LaTeX 的数学排版问题。起点是 JLDiaz 的解决方案，它基于 Andrew Swann 的答案。

\comp应该是二元运算符（\mathbin）。
的内容\comp设置为数学。
如果在下标、分数内使用数学，则数学会自动调整大小。tikz解决方案切换到文本模式并返回数学。我们需要知道哪种样式处于活动状态（\displaystyle、\textstyle、\scriptstyle、\scriptscriptstyle）。LaTeX\mathpalette有助于设置此样式（它使用 TeX 的\mathchoice）。
数学符号周围可以添加空格，由控制\mathsurround。当我们从文本切换到数学符号时，这些空格不能添加。LaTeX 可以\m@th帮到这种情况，因为它设置\mathsurround为0pt。
我从切换到ex以mu获得更好的缩放行为，并使用 dimen 寄存器来设置包括和在内tikz的参数。inner sepline width
在脚本样式中，TeX 不会在二元运算符周围设置额外的空间。但恕我直言，如果相邻符号比其内容更靠近框，它看起来会有点奇怪。因此，在脚本样式中添加了一半细的空格。在显示和文本样式中添加了四分之一细的空格。\nonscript忽略脚本样式中的以下数学胶水。
此外minimum width，还添加了一条隐形规则来改善微小或空内容的行为。
\comp有一个可选参数，可以将选项传递给节点设置。

文件：

\documentclass{article}

\usepackage{tikz}
\usetikzlibrary{shapes}
\usepackage{color}

\makeatletter
\newcommand*\comp[2][]{%
  \ensuremath{%
    \mathbin{%
      \mathpalette{\comp@aux{#1}}{#2}%
    }%
  }%
}
\newdimen\comp@unit
\newcommand*{\comp@aux}[3]{%
  #2%
  \mskip.5\thinmuskip\nonscript\mskip-.25\thinmuskip
  \begingroup
    \sbox0{%
      $%
        \m@th % \mathsurround=0pt
        #2% \displaystyle, \textstyle, ...
        \mkern9mu %
      $%
    }%
  \edef\x{\endgroup
    \comp@unit=\the\wd0 %
  }\x
  \tikz[baseline=(char.base)]{%
    \node[
      rectangle,
      draw,
      minimum height=2\comp@unit,
      minimum width=2\comp@unit,
      rounded corners=\comp@unit,
      inner sep=.33\comp@unit,
      line width=.05\comp@unit,
      #1%
    ] (char) {%
      $%
        \m@th % \mathsurround=0pt
        #2% \displaystyle, \textstyle, ...
        \rule{0pt}{\comp@unit}%
        #3%
      $%
    };%
  }%
  \mskip.5\thinmuskip\nonscript\mskip-.25\thinmuskip
}
\makeatother

\begin{document}

$a \oplus b \ominus c$

$a \comp{x} b \comp{y} c \comp{} d \comp{Z} e \comp{\cdot} f$

$a \comp{x+y+z} b \comp{\displaystyle\int_0^\infty \frac{x}{z}\,\mathrm{d}x} c$

$a \comp{x} b^{c \comp{y} d}
\frac{e \comp{z} f}{g \comp{2x} h_{i \comp{2y} j}}$

$a \comp[red]{r} b \comp[green]{g} c \comp[blue]{b} d$

\end{document}

$\comp 示例$

Answer

这个答案处理 TeX/LaTeX 的数学排版问题。起点是 JLDiaz 的解决方案，它基于 Andrew Swann 的答案。

\comp应该是二元运算符（\mathbin）。
的内容\comp设置为数学。
如果在下标、分数内使用数学，则数学会自动调整大小。tikz解决方案切换到文本模式并返回数学。我们需要知道哪种样式处于活动状态（\displaystyle、\textstyle、\scriptstyle、\scriptscriptstyle）。LaTeX\mathpalette有助于设置此样式（它使用 TeX 的\mathchoice）。
数学符号周围可以添加空格，由控制\mathsurround。当我们从文本切换到数学符号时，这些空格不能添加。LaTeX 可以\m@th帮到这种情况，因为它设置\mathsurround为0pt。
我从切换到ex以mu获得更好的缩放行为，并使用 dimen 寄存器来设置包括和在内tikz的参数。inner sepline width
在脚本样式中，TeX 不会在二元运算符周围设置额外的空间。但恕我直言，如果相邻符号比其内容更靠近框，它看起来会有点奇怪。因此，在脚本样式中添加了一半细的空格。在显示和文本样式中添加了四分之一细的空格。\nonscript忽略脚本样式中的以下数学胶水。
此外minimum width，还添加了一条隐形规则来改善微小或空内容的行为。
\comp有一个可选参数，可以将选项传递给节点设置。

文件：

\documentclass{article}

\usepackage{tikz}
\usetikzlibrary{shapes}
\usepackage{color}

\makeatletter
\newcommand*\comp[2][]{%
  \ensuremath{%
    \mathbin{%
      \mathpalette{\comp@aux{#1}}{#2}%
    }%
  }%
}
\newdimen\comp@unit
\newcommand*{\comp@aux}[3]{%
  #2%
  \mskip.5\thinmuskip\nonscript\mskip-.25\thinmuskip
  \begingroup
    \sbox0{%
      $%
        \m@th % \mathsurround=0pt
        #2% \displaystyle, \textstyle, ...
        \mkern9mu %
      $%
    }%
  \edef\x{\endgroup
    \comp@unit=\the\wd0 %
  }\x
  \tikz[baseline=(char.base)]{%
    \node[
      rectangle,
      draw,
      minimum height=2\comp@unit,
      minimum width=2\comp@unit,
      rounded corners=\comp@unit,
      inner sep=.33\comp@unit,
      line width=.05\comp@unit,
      #1%
    ] (char) {%
      $%
        \m@th % \mathsurround=0pt
        #2% \displaystyle, \textstyle, ...
        \rule{0pt}{\comp@unit}%
        #3%
      $%
    };%
  }%
  \mskip.5\thinmuskip\nonscript\mskip-.25\thinmuskip
}
\makeatother

\begin{document}

$a \oplus b \ominus c$

$a \comp{x} b \comp{y} c \comp{} d \comp{Z} e \comp{\cdot} f$

$a \comp{x+y+z} b \comp{\displaystyle\int_0^\infty \frac{x}{z}\,\mathrm{d}x} c$

$a \comp{x} b^{c \comp{y} d}
\frac{e \comp{z} f}{g \comp{2x} h_{i \comp{2y} j}}$

$a \comp[red]{r} b \comp[green]{g} c \comp[blue]{b} d$

\end{document}

$\comp 示例$

Question 2

使用tikzAndrew Swann 的答案中的方法，但使用圆角矩形而不是椭圆形，并仔细设置角半径和矩形高度，您可以得到一个很好的近似值：

\documentclass{article}
\usepackage{tikz}
\begin{document}
\thispagestyle{empty}

\usetikzlibrary{shapes}

\newcommand*\compel[1]{\tikz[baseline=(char.base)]{
\node[rectangle,draw,minimum height=3ex, minimum width=3ex, rounded corners=1.5ex] (char) {#1};}}

\compel{x} \compel{\( x+y+z \)}

\end{document}

Answer

使用tikzAndrew Swann 的答案中的方法，但使用圆角矩形而不是椭圆形，并仔细设置角半径和矩形高度，您可以得到一个很好的近似值：

\documentclass{article}
\usepackage{tikz}
\begin{document}
\thispagestyle{empty}

\usetikzlibrary{shapes}

\newcommand*\compel[1]{\tikz[baseline=(char.base)]{
\node[rectangle,draw,minimum height=3ex, minimum width=3ex, rounded corners=1.5ex] (char) {#1};}}

\compel{x} \compel{\( x+y+z \)}

\end{document}

Question 3

调整答案以制作 \textcircled 数字的好方法？可以使用ellipse来自的形状tikz。

\documentclass{article}

\usepackage{tikz}
\usetikzlibrary{shapes}

\newcommand*\compel[1]{\tikz[baseline=(char.base)]{
\node[ellipse,draw,inner sep=0.5pt] (char) {#1};}}

\begin{document}
\compel{x} \compel{\( x+y+z \)}

\end{document}

椭圆示例

形状cylinder与你的愿望非常接近

\newcommand*\compcy[1]{\tikz[baseline=(char.base)]{
\node[cylinder,draw,inner sep=0.5pt] (char) {#1}; }}

\compcy{x} \compcy{\( x+y+z \)}

圆柱体样品

因此人们可以疯狂地尝试修改该代码：

\documentclass{article}

\usepackage{tikz}
\usetikzlibrary{shapes}

\makeatletter
% Keys for shape flatcircle
%
% /pgf/shape aspect              : Ratio between the x and y radii of the flatcircle end.
% /pgf/flatcircle uses custom fill : Use a custom fill for the flatcircle.
% /pgf/flatcircle end fill         : Custom color for the flatcircle end.
% /pgf/flatcircle body fill        : Custom color for the flatcirclebody.
%

\newif\ifpgfflatcircleusescustomfill
\pgfkeys{/pgf/.cd,
    flatcircle uses custom fill/.is if=pgfflatcircleusescustomfill,
    flatcircle end fill/.initial=white,
    flatcircle body fill/.initial=white
}


\pgfdeclareshape{flatcircle}{%
    \savedmacro\getflatcirclepoints{%
        \pgfmathsetlength\pgf@xc{\pgfkeysvalueof{/pgf/inner xsep}}%
        \pgf@x\pgf@xc%
        \advance\[email protected]\wd\pgfnodeparttextbox%
        \pgfmathsetlength\pgf@yc{\pgfkeysvalueof{/pgf/inner ysep}}%
        \pgf@y\pgf@yc%
        \advance\[email protected]\ht\pgfnodeparttextbox%
        \advance\[email protected]\dp\pgfnodeparttextbox%
        \ifpgfshapeborderusesincircle%
            \pgfmathsetmacro\rotate{\pgfkeysvalueof{/pgf/shape border rotate}}%
            \ifdim\pgf@x<\pgf@y%
                \pgf@x\pgf@y%
            \else%
                \pgf@y\pgf@x%
            \fi%
            \[email protected]\pgf@x%
            \[email protected]\pgf@y%           
        \else%
            \pgfmathmod{\pgfkeysvalueof{/pgf/shape border rotate}}{360}%
            \ifdim\pgfmathresult pt<0pt\relax%
                \pgfmathadd@{\pgfmathresult}{360}%
            \fi%
            \pgfmathsetcount\c@pgf@counta{+\pgfmathresult}%
            \advance\c@pgf@counta45\relax%
            \divide\c@pgf@counta90\relax%
            \multiply\c@pgf@counta90\relax%
            \edef\rotate{\the\c@pgf@counta}%
            \ifnum\c@pgf@counta=90\relax%
                \pgf@xa\pgf@x%
                \pgf@x\pgf@y%
                \pgf@y\pgf@xa%
                \pgf@yc\pgf@xc%
            \else%
                \ifnum\c@pgf@counta=270\relax%
                    \pgf@xa\pgf@x%
                    \pgf@x\pgf@y%
                    \pgf@y\pgf@xa%
                    \pgf@yc\pgf@xc%
                \fi%
            \fi%
        \fi%
        \addtosavedmacro\rotate%
        \pgf@xa\pgf@x%
        \pgf@ya\pgf@y%
        \pgfutil@tempdima\pgfshapeaspect\pgf@ya%
        \pgfutil@tempdimb\pgf@ya%
        %
        % Adjust for minimum height.
        %
        \pgfmathsetlength\pgf@xc{\pgfkeysvalueof{/pgf/minimum width}}%
        \ifdim\pgfutil@tempdimb<.5\pgf@xc\relax%
            \[email protected]\pgf@xc%
            \pgf@ya\pgfutil@tempdimb%
        \fi%
        %
        % Calculate how far the node contents can extend into the flatcircle bottom.
        %
        \pgf@yb\pgfutil@tempdimb%
        \advance\pgf@yb-\pgf@yc%
        \pgfmathdivide@{\pgfmath@tonumber{\pgf@yb}}{\pgfmath@tonumber{\pgfutil@tempdimb}}%
        \pgfmathasin@{\pgfmathresult}%
        \pgfmathcos@{\pgfmathresult}%
        \let\angle\pgfmathresult%
        \pgf@xb\pgfmathresult\pgfutil@tempdima%
        %
        % Adjust for minimum width.
        %
        \[email protected]\pgflinewidth%
        \advance\[email protected]\pgf@xa%
        \advance\[email protected]\pgfutil@tempdima%
        \advance\pgf@x-\pgf@xb%
        \pgfmathsetlength\pgf@xc{\pgfkeysvalueof{/pgf/minimum height}}%
        \ifdim\pgf@x<\pgf@xc%
            \advance\pgf@xc-\pgf@x%
            \advance\[email protected]\pgf@xc%
        \fi%        
        %
        % Add the larger of the outer sep to the radii.
        %
        \pgf@x\pgfutil@tempdima\relax%
        \pgf@y\pgfutil@tempdimb\relax%
        \pgfmathsetlength\pgf@xc{\pgfkeysvalueof{/pgf/outer xsep}}%
        \pgfmathsetlength\pgf@yc{\pgfkeysvalueof{/pgf/outer ysep}}%
        \ifdim\pgf@xc>\pgf@yc%
            \advance\pgf@x\pgf@xc%
            \advance\pgf@y\pgf@xc%
            \edef\outersep{\the\pgf@xc}%
        \else%
            \advance\pgf@x\pgf@yc%
            \advance\pgf@y\pgf@yc%
            \edef\outersep{\the\pgf@yc}%
        \fi%
        \edef\xradius{\the\pgf@x}%
        \edef\yradius{\the\pgf@y}%
        \addtosavedmacro\xradius%
        \addtosavedmacro\yradius%
        \addtosavedmacro\outersep%
        %
        \pgfextract@process\flatcirclecenter{%
            \pgf@x\pgfutil@tempdima%
            \advance\[email protected]\pgflinewidth%
            \advance\pgf@x\pgf@xb%
            \[email protected]\pgf@x% 
            \pgf@y0pt%
        }%
        \addtosavedmacro\flatcirclecenter%
        %
        \pgfextract@process\beforetop{%
            \pgf@x\pgf@xa%
                        \advance\pgf@x-\pgf@xb%
%           \advance\pgf@x\pgfutil@tempdima%
%           \advance\[email protected]\pgflinewidth%
            \pgf@y\pgf@ya%
        }%
        \pgfextract@process\afterbottom{%
            \pgf@x-\pgf@xa%
            \advance\pgf@x\pgf@xb%
            \pgf@y\pgf@ya%
        }%
        \addtosavedmacro\beforetop%
        \addtosavedmacro\afterbottom%       
        \pgfmathsetlength\pgf@yc{\pgfkeysvalueof{/pgf/outer ysep}}%
        \pgfextract@process\beforetopanchor{%
            \beforetop%
            \advance\pgf@y\pgf@yc%
        }%
        \pgfextract@process\afterbottomanchor{%
            \afterbottom%
            \advance\pgf@y\pgf@yc%
        }%
        \addtosavedmacro\beforetopanchor%       
        \addtosavedmacro\afterbottomanchor% 
        %
        \beforetopanchor%
        \advance\pgf@x\xradius\relax%
        \ifdim\pgf@x>\pgf@y%
            \edef\externalradius{\the\pgf@x}%
        \else%
            \edef\externalradius{\the\pgf@y}%
        \fi%
        \addtosavedmacro\externalradius%
    }
    \savedanchor\centerpoint{%
        \[email protected]\wd\pgfnodeparttextbox%
        \[email protected]\ht\pgfnodeparttextbox%
        \advance\[email protected]\dp\pgfnodeparttextbox%
    }%
    \savedanchor\midpoint{%
        \[email protected]\wd\pgfnodeparttextbox%
        \pgfmathsetlength\pgf@y{+0.5ex}%
    }%
    \savedanchor\basepoint{%
        \[email protected]\wd\pgfnodeparttextbox%
        \pgf@y0pt%
    }%
    \anchor{center}{\centerpoint}
    \anchor{shape center}{%
        \getflatcirclepoints%
        \pgfmathrotatepointaround{\pgfpointadd{\flatcirclecenter}{\centerpoint}}%
            {\centerpoint}{\rotate}%    
    }%
    \anchor{mid}{\midpoint}%
    \anchor{mid east}{%
        \getflatcirclepoints%
        \let\pgf@flatcircle@referencepoint\midpoint%
        \pgf@anchor@flatcircle@border{\pgfqpoint{\externalradius}{0pt}}%
    }%
    \anchor{mid west}{%
        \getflatcirclepoints%
        \let\pgf@flatcircle@referencepoint\midpoint%
        \pgf@anchor@flatcircle@border{\pgfqpoint{-\externalradius}{0pt}}%
    }%
    \anchor{base}{\basepoint}%
    \anchor{base east}{%
        \getflatcirclepoints%
        \let\pgf@flatcircle@referencepoint\basepoint%
        \pgf@anchor@flatcircle@border{\pgfqpoint{\externalradius}{0pt}}%
    }%
    \anchor{base west}{%
        \getflatcirclepoints%
        \let\pgf@flatcircle@referencepoint\basepoint%
        \pgf@anchor@flatcircle@border{\pgfqpoint{-\externalradius}{0pt}}%
    }%
    \anchor{north}{%
        \getflatcirclepoints%
        \pgf@anchor@flatcircle@border{\pgfqpoint{0pt}{\externalradius}}%
    }%
    \anchor{south}{%
        \getflatcirclepoints%
        \pgf@anchor@flatcircle@border{\pgfqpoint{0pt}{-\externalradius}}%
    }%
    \anchor{east}{%
        \getflatcirclepoints%
        \pgf@anchor@flatcircle@border{\pgfqpoint{\externalradius}{0pt}}%
    }%
    \anchor{west}{%
        \getflatcirclepoints%
        \pgf@anchor@flatcircle@border{\pgfqpoint{-\externalradius}{0pt}}%
    }%
    \anchor{north east}{%
        \getflatcirclepoints%
        \pgf@anchor@flatcircle@border{\pgfqpoint{\externalradius}{\externalradius}}%
    }%
    \anchor{south west}{%
        \getflatcirclepoints%
        \pgf@anchor@flatcircle@border{\pgfqpoint{-\externalradius}{-\externalradius}}%
    }%
    \anchor{south east}{%
        \getflatcirclepoints%
        \pgf@anchor@flatcircle@border{\pgfqpoint{\externalradius}{-\externalradius}}%
    }%
    \anchor{north west}{%
        \getflatcirclepoints%
        \pgf@anchor@flatcircle@border{\pgfqpoint{-\externalradius}{\externalradius}}%
    }%
    \anchor{before top}{%
        \getflatcirclepoints%
        \pgfmathrotatepointaround{\pgfpointadd{\beforetopanchor}{\centerpoint}}{\centerpoint}{\rotate}%
    }
    \anchor{top}{%
        \getflatcirclepoints%
        \pgfmathrotatepointaround{%
            \pgfpointadd{%
                \beforetop%
                \pgf@y0pt\relax%
                \advance\pgf@x\xradius\relax%
            }{\centerpoint}}{\centerpoint}{\rotate}%
    }
    \anchor{after top}{%
        \getflatcirclepoints%
        \pgfmathrotatepointaround{\pgfpointadd{\beforetopanchor\pgf@y-\pgf@y}{\centerpoint}}{\centerpoint}{\rotate}%
    }
    \anchor{before bottom}{%
        \getflatcirclepoints%
        \pgfmathrotatepointaround{\pgfpointadd{\afterbottomanchor\pgf@y-\pgf@y}{\centerpoint}}{\centerpoint}{\rotate}%
    }
    \anchor{bottom}{%
        \getflatcirclepoints%
        \pgfmathrotatepointaround{%
            \pgfpointadd{%
                \afterbottom%
                \pgf@y0pt\relax%
                \advance\pgf@x-\xradius\relax%
            }{\centerpoint}}{\centerpoint}{\rotate}%
    }
    \anchor{after bottom}{%
        \getflatcirclepoints%
        \pgfmathrotatepointaround{\pgfpointadd{\afterbottomanchor}{\centerpoint}}{\centerpoint}{\rotate}%
    }   
    \backgroundpath{%
        \getflatcirclepoints%
        {%
            \pgf@x\xradius\relax%
            \advance\pgf@x-\outersep\relax%
            \edef\xradius{\the\pgf@x}%
            \pgf@y\yradius\relax%
            \advance\pgf@y-\outersep\relax%
            \edef\yradius{\the\pgf@y}%
            \pgftransformshift{\centerpoint}%
            \pgftransformrotate{\rotate}%
            \pgfpathmoveto{\afterbottom}%
            \pgfpatharc{90}{270}{\xradius and \yradius}%
            \pgfpathlineto{\beforetop\pgf@y-\pgf@y}%
            \pgfpatharc{-90}{90}{\xradius and \yradius}%
            \pgfpathclose%
%           \pgfpathmoveto{\beforetop}%
%           \pgfpatharc{90}{270}{\xradius and \yradius}%
        }%
    }%
    \behindbackgroundpath{%
        \ifpgfflatcircleusescustomfill%
            \getflatcirclepoints%
            \pgf@x\xradius\relax%
            \advance\pgf@x-\outersep\relax%
            \edef\xradius{\the\pgf@x}%
            \pgf@y\yradius\relax%
            \advance\pgf@y-\outersep\relax%
            \edef\yradius{\the\pgf@y}%
            {%              
                \pgftransformshift{\centerpoint}%
                \pgftransformrotate{\rotate}%
                \pgfpathmoveto{\afterbottom}%
                \pgfpatharc{90}{270}{\xradius and \yradius}%
                \pgfpathlineto{\beforetop\pgf@y-\pgf@y}%
                \pgfpatharc{270}{90}{\xradius and \yradius}%
                \pgfpathclose%
                \expandafter\pgfsetfillcolor\expandafter{\pgfkeysvalueof{/pgf/flatcircle body fill}}%
                \pgfusepath{fill}%
                %
                \pgfpathmoveto{\beforetop}%
                \pgfpatharc{90}{-270}{\xradius and \yradius}%
                \pgfpathclose
                \expandafter\pgfsetfillcolor\expandafter{\pgfkeysvalueof{/pgf/flatcircle end fill}}%
                \pgfusepath{fill}%
            }%      
        \fi%    
    }%
    \anchorborder{%
        \pgfextract@process\externalpoint{}%
        \getflatcirclepoints%
        \pgfutil@ifundefined{pgf@flatcircle@referencepoint}{\let\referencepoint\centerpoint}{%
            \let\referencepoint\pgf@flatcircle@referencepoint}%
        \pgfextract@process\externalpoint{%
            \externalpoint%
            \pgf@xa\pgf@x%
            \pgf@ya\pgf@y%
            \referencepoint%
            \advance\pgf@x\pgf@xa%
            \advance\pgf@y\pgf@ya%
        }%
        \pgfmathanglebetweenpoints{\centerpoint}{\externalpoint}%
        \pgfmathsubtract@{\pgfmathresult}{\rotate}%
        \ifdim\pgfmathresult pt<0pt\relax%
            \pgfmathadd@{\pgfmathresult}{360}%
        \fi%
        \let\externalangle\pgfmathresult%
        %
        \pgfmathanglebetweenpoints{\referencepoint}{\pgfpointadd{\afterbottomanchor}{\centerpoint}}%
        \ifdim\externalangle pt<\pgfmathresult pt\relax%
            \pgfmathanglebetweenpoints{\referencepoint}{\pgfpointadd{\beforetopanchor}{\centerpoint}}%
            \ifdim\externalangle pt<\pgfmathresult pt\relax%
                \pgfmathrotatepointaround{%
                    \pgfmathpointintersectionoflineandarc%
                        {\pgfmathrotatepointaround{\externalpoint}{\centerpoint}{-\rotate}}%
                        {\pgfmathrotatepointaround{\referencepoint}{\centerpoint}{-\rotate}}%
                        {%
                            \beforetop%
                            \pgf@xa\pgf@x%
                            \centerpoint%
                            \advance\pgf@x\pgf@xa%
                        }%
                        {0}{90}{\xradius and \yradius}%
                    }{\centerpoint}{\rotate}%
            \else%
                \pgfpointintersectionoflines{%
                    \pgfmathrotatepointaround{\pgfpointadd{\afterbottomanchor}{\centerpoint}}%
                        {\centerpoint}{\rotate}}{%
                    \pgfmathrotatepointaround{\pgfpointadd{\beforetopanchor}{\centerpoint}}%
                        {\centerpoint}{\rotate}}%
                    {\referencepoint}{\externalpoint}%
            \fi%
        \else%
            \pgfmathanglebetweenpoints{\referencepoint}{\pgfpointadd{\afterbottomanchor\pgf@y-\pgf@y}{\centerpoint}}%
            \ifdim\externalangle pt>\pgfmathresult pt\relax%
                \pgfmathanglebetweenpoints{\referencepoint}{\pgfpointadd{\beforetopanchor\pgf@y-\pgf@y}{\centerpoint}}%
                \ifdim\externalangle pt>\pgfmathresult pt\relax%
                    \pgfmathrotatepointaround{%
                        \pgfmathpointintersectionoflineandarc%
                            {\pgfmathrotatepointaround{\externalpoint}{\centerpoint}{-\rotate}}%
                            {\pgfmathrotatepointaround{\referencepoint}{\centerpoint}{-\rotate}}%
                            {%
                                \beforetop%
                                \pgf@xa\pgf@x%
                                \centerpoint
                                \advance\pgf@x\pgf@xa%
                            }%
                            {270}{360}{\xradius and \yradius}%
                        }{\centerpoint}{\rotate}%
                \else%
                    \pgfpointintersectionoflines{%
                        \pgfmathrotatepointaround{\pgfpointadd{\afterbottomanchor\pgf@y-\pgf@y}{\centerpoint}}%
                            {\centerpoint}{\rotate}}{%
                        \pgfmathrotatepointaround{\pgfpointadd{\beforetopanchor\pgf@y-\pgf@y}{\centerpoint}}%
                            {\centerpoint}{\rotate}}%
                        {\referencepoint}{\externalpoint}%
                \fi%
            \else%
                \pgfmathrotatepointaround{%
                    \pgfmathpointintersectionoflineandarc%
                        {\pgfmathrotatepointaround{\externalpoint}{\centerpoint}{-\rotate}}%
                        {\pgfmathrotatepointaround{\referencepoint}{\centerpoint}{-\rotate}}%
                        {%
                            \afterbottom%
                            \pgf@xa\pgf@x%
                            \centerpoint
                            \advance\pgf@x\pgf@xa%
                        }%
                        {90}{270}{\xradius and \yradius}%
                    }{\centerpoint}{\rotate}%
            \fi%
        \fi%
    }
}
\makeatother

\newcommand*\comp[1]{\tikz[baseline=(char.base)]{
\node[flatcircle,draw,inner ysep=1pt,inner xsep=0pt] (char) {#1};}}

\begin{document}
\comp{x} \comp{\( x+y+z \)} \comp{y} \comp{\( \int \)}

\end{document}

平圆样品

这只是圆柱形状的代码pgflibraryshapes.geometric.code.tex，其中几行被注释掉了。我在整个过程cylinder中用替换了flatcircle，注释掉了在圆柱右侧绘制左点半圆的行，注释掉了将\pgfextract@process\beforetop圆柱右侧向右移动的移动命令，并将校正符号翻转为\pgf@x。\pgf@xb最后，在调用此代码时，分别在 x 和 y 方向上设置内部分离，在第一种情况下会产生一个圆形。代码很长，因为它包括设置锚点、允许旋转等所有 pgf 材料。

Answer