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如何在程序的控制流图中用 Tikz 绘制弯曲边缘

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如何在程序的控制流图中用 Tikz 绘制弯曲边缘

我正在尝试使用 Tikz 绘制程序的控制流图，并希望渲染像下图这样的输出，但我无法在给定的图中绘制弯曲边缘。

在此处输入图片描述

用于相同的代码（但用于不同的程序）

\begin{figure}    
\begin{tikzpicture}
[%
    ->,
    shorten >=2pt,
    >=stealth,
    node distance=1cm,
    noname/.style={%
      rounded corners=0.5em,
      minimum width=5em,
      minimum height=3em,
      draw,
    }
  ]
    \node[noname] (1)                                             {$Start : P$};
    \node[noname] (2) [below=of 1]                                {$c=3$};
    \node[noname] (3) [node distance=1cm and 3mm,below left=of 2] {$b = a*b$};
    \node[noname] (4) [node distance=1cm and 3mm,below right=of 2]{print $a*c$};
    \node[noname] (5) [node distance=3cm,below=of 4]              {$a=b*c$};
    \node[noname] (6) [below=of 3]                                {print $a*b$};
    \node[noname] (7) [below=of 6]                                {$Call : P$};
    \node[noname] (8) [node distance=1cm,below=of 7]              {$Return : P$};
    \node[noname] (9) [below right=of 8]                          {$Exits : P$};
    \node[noname] (10) [node distance=6cm,right =of 1]            {$Start : main$};
    \node[noname] (11) [below=of 10]                              {$a = 3$};    
    \node[noname] (12) [below=of 11]                              {$b = a*b$};    
    \node[noname] (13) [below=of 12]                              {$Call : P$};    
    \node[noname] (14) [below=of 13]                              {$Return : P$};    
    \node[noname] (15) [below=of 14]                              {$c = a*b$};    
    \node[noname] (16) [below=of 15]                              {$Exit : main$};    
    \path (1) edge                   node {} (2)
          (2) edge                   node {} (3)
          (2) edge                   node {} (4)
          (3) edge                   node {} (6)
          (4) edge                   node {} (5)
          (6) edge                   node {} (7)
          (7) edge                   node {} (8)
          (8) edge                   node {} (9)
          (5) edge [bend left = 2em]                  node {} (9)
          (10) edge                   node {} (11)
          (11) edge                   node {} (12)
          (12) edge                   node {} (13)
          (13) edge                   node {} (14)
          (14) edge                   node {} (15)
          (15) edge                   node {} (16)
          (13) edge [bend right = 1.4em]                   node {} (1)
          (9) edge  [bend left = 2.1em]                   node {} (14)
\end{tikzpicture}
\caption{Supergraph for given program} 
\label{fig:1}
\end{figure}

但它输出的图像如下：

这是另一个程序的 cfg

我怎样才能改变节点的边缘致电：P到节点开始 ： P和节点退出 ： P到节点返回 ： P到上面所需图中绘制的那个

答案1

您可以使用 的in和out选项edge，这可以让您定义路径与节点相交的角度。例如out=45表示路径从起始节点向右上方延伸，而in=45表示路径从结束节点的右上方进入。

dotted将使线变成虚线。

因此，如果你将图中的最后两个边改为

      (13) edge [out=230,in=45,dotted]                   node {} (1)
      (9) edge  [out=-30,in=180,dotted]                   node {} (14);

你得到：

在此处输入图片描述

下面是完整代码。（当然，你不需要为所有边添加空节点，因此我删除了node{}。）

\documentclass{standalone}
\usepackage{tikz}
\usetikzlibrary{positioning}
\begin{document}
\begin{tikzpicture}
[%
    ->,
    shorten >=2pt,
    >=stealth,
    node distance=1cm,
    noname/.style={%
      rounded corners=0.5em,
      minimum width=5em,
      minimum height=3em,
      draw,
    }
  ]
    \node[noname] (1)                                             {$Start : P$};
    \node[noname] (2) [below=of 1]                                {$c=3$};
    \node[noname] (3) [node distance=1cm and 3mm,below left=of 2] {$b = a*b$};
    \node[noname] (4) [node distance=1cm and 3mm,below right=of 2]{print $a*c$};
    \node[noname] (5) [node distance=3cm,below=of 4]              {$a=b*c$};
    \node[noname] (6) [below=of 3]                                {print $a*b$};
    \node[noname] (7) [below=of 6]                                {$Call : P$};
    \node[noname] (8) [node distance=1cm,below=of 7]              {$Return : P$};
    \node[noname] (9) [below right=of 8]                          {$Exits : P$};
    \node[noname] (10) [node distance=6cm,right =of 1]            {$Start : main$};
    \node[noname] (11) [below=of 10]                              {$a = 3$};    
    \node[noname] (12) [below=of 11]                              {$b = a*b$};    
    \node[noname] (13) [below=of 12]                              {$Call : P$};    
    \node[noname] (14) [below=of 13]                              {$Return : P$};    
    \node[noname] (15) [below=of 14]                              {$c = a*b$};    
    \node[noname] (16) [below=of 15]                              {$Exit : main$};    
    \path (1) edge                   (2)
          (2) edge                   (3)
          (2) edge                   (4)
          (3) edge                   (6)
          (4) edge                   (5)
          (6) edge                   (7)
          (7) edge                   (8)
          (8) edge                   (9)
          (5) edge [bend left = 2em]                  (9)
          (10) edge                   (11)
          (11) edge                   (12)
          (12) edge                   (13)
          (13) edge                   (14)
          (14) edge                   (15)
          (15) edge                   (16)
          (13) edge [out=230,in=45,dotted]                   (1)
          (9) edge  [out=-30,in=180,dotted]                   (14);
\end{tikzpicture}
\end{document}

答案2

使用.. controls <first control point> and <second control point> .. <end point>

\begin{tikzpicture}
[%
    ->,
    shorten >=2pt,
    >=stealth,
    node distance=1cm,
    noname/.style={%
      rounded corners=0.5em,
      minimum width=5em,
      minimum height=3em,
      draw,
    }
  ]
    \node[noname] (1)                                             {$Start : P$};
    \node[noname] (2) [below=of 1]                                {$c=3$};
    \node[noname] (3) [node distance=1cm and 3mm,below left=of 2] {$b = a*b$};
    \node[noname] (4) [node distance=1cm and 3mm,below right=of 2]{print $a*c$};
    \node[noname] (5) [node distance=3cm,below=of 4]              {$a=b*c$};
    \node[noname] (6) [below=of 3]                                {print $a*b$};
    \node[noname] (7) [below=of 6]                                {$Call : P$};
    \node[noname] (8) [node distance=1cm,below=of 7]              {$Return : P$};
    \node[noname] (9) [below right=of 8]                          {$Exits : P$};
    \node[noname] (10) [node distance=6cm,right =of 1]            {$Start : main$};
    \node[noname] (11) [below=of 10]                              {$a = 3$};    
    \node[noname] (12) [below=of 11]                              {$b = a*b$};    
    \node[noname] (13) [below=of 12]                              {$Call : P$};    
    \node[noname] (14) [below=of 13]                              {$Return : P$};    
    \node[noname] (15) [below=of 14]                              {$c = a*b$};    
    \node[noname] (16) [below=of 15]                              {$Exit : main$};    
    \draw (1) edge (2)
          (2) edge (3)
          (2) edge (4)
          (3) edge (6)
          (4) edge (5)
          (6) edge (7)
          (7) edge (8)
          (8) edge (9)
          (5) edge [bend left = 2em] (9)
          (10) edge (11)
          (11) edge (12)
          (12) edge (13)
          (13) edge (14)
          (14) edge (15)
          (15) edge (16);
    \draw[->] (13) .. controls +(left:4cm) and +(right:4cm) .. (1);
    \draw[->] (9)[anchor=east] .. controls +(right:3cm) and +(left:5cm) .. (14);
\end{tikzpicture}

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