关于绘制集合补集的维恩图的问题

Question

我对 TikZ 的了解非常有限。我在我的文档中绘制了这种风格的维恩图：

\begin{figure}[H]
    \centering
\begin{tikzpicture}
\def\firstcircle{(0,0) circle (1.5cm)}
\def\secondcircle{(0:2cm) circle (1.5cm)}

\colorlet{circle edge}{red!50}
\colorlet{circle area}{red!20}

\tikzset{filled/.style={fill=circle area, draw=circle edge, thick},
    outline/.style={draw=circle edge, thick}}

\setlength{\parskip}{5mm}
\begin{scope}
\clip \firstcircle;
\fill[filled] \secondcircle;
\end{scope}
\draw[outline] \firstcircle node {$M_1$};
\draw[outline] \secondcircle node {$M_2$};
\node[anchor=south] at (current bounding box.north) {$M_1 \cap M_2$};
\end{tikzpicture}
\end{figure}

现在，我想画一个补集在维基百科上查看此内容，所以我需要在其周围画一个框并填充一些颜色。操作应该在图片的顶部（如上图所示）。有人知道如何以与第一张图相同的一般风格做到这一点吗？

谢谢你！

Answer 1

\documentclass[tikz, margin=3mm]{standalone}
\usetikzlibrary{backgrounds, fit}

\begin{document}
\begin{tikzpicture}
\def\firstcircle{(0,0) circle (1.5cm)}
\def\secondcircle{(0:2cm) circle (1.5cm)}

\colorlet{circle edge}{red!50}
\colorlet{circle area}{red!20}

\tikzset{
    filled/.style = {draw=circle edge, fill=#1!, thick},
   outline/.style = {draw=circle edge, thick},
         F/.style = {draw, inner sep=7mm, fit=(current bounding box),
                  node contents={}}
}
\draw[filled=white] \firstcircle node {$M_1$};
\draw[outline] \secondcircle node {$M_2$};
\scoped[on background layer]
 \node (a) [F, fill=circle area];  
\node[anchor=north] at (current bounding box.north) {A^c=M_1 \setminus M_2};
\end{tikzpicture}
\end{document}