如何从文本到节点添加箭头？

Question

我目前正在使用 Tikz 绘制有限自动机。我需要从一段文本向有限自动机的一个节点添加一个箭头，如示例所示。

我尝试使用“draw=none”创建节点。但是，这引发了两个问题。我无法在两行上写入所需的文本，而且，虽然创建了节点的边界框，但并未显示，因此箭头看起来非常糟糕，因为如此长的文本的边界框非常大。

\documentclass[11pt]{report}

\usepackage{pgf}
\usepackage{tikz}
\usetikzlibrary{arrows, automata}

\begin{document}

(not important stuff)

\begin{tikzpicture}[->,>=stealth', shorten >=1pt, auto, node distance=2.8cm, semithick]
\node[state] (A)                    {$Alarm$};
\node[state] (B) [above of=A]       {$Reset$};
\node[state] (C) [above right of=A] {$S1$};
\node[state] (D) [right of=A]       {$S2$};
\node[state] (E) [below right of=A] {$S3$};
\node[state] (F) [below of=A]       {$S4$};
\node[state] (G) [left of=A]        {$Open$};
\node[statem, draw=none] (H) [above left of=B] {Reset input(from any state)};

\path (A) edge [loop left]  node {0, 1} (A)
      (B) edge [bend left]  node {1}    (C)
          edge              node {0}    (A)
      (C) edge [bend left]  node {0}    (D)
          edge              node {1}    (A)
      (D) edge [bend left]  node {1}    (E)
          edge              node {0}    (A)
      (E) edge [bend left]  node {1}    (F)
          edge              node {0}    (A)
      (F) edge [bend left]  node {0}    (G)
          edge              node {1}    (A)
      (G) edge [bend left]  node {0}    (B)
          edge [loop left]  node {1}    (G)
      (H) edge              node {}     (B);
\end{tikzpicture}

(more not important stuff)

\end{document}

PS 如果知道如何将箭头移动到边缘的中间也会很感激（目前它们位于边缘的末端）。

Answer 1

以下是使用automata库和装饰将箭头放置在边缘中间的一种可能性：

代码：

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{automata,decorations.markings,positioning,arrows}

\begin{document}

\begin{tikzpicture}[
midarr/.style 2 args={
  decoration={
    markings,
    mark=at position 0.5 with {\arrow[xshift=3.333pt]{triangle 45} \node[#1] {#2};},
  },
    postaction=decorate,
},
state/.append style={minimum size=35pt},
node distance=1.3cm and 1.3cm
]
\node[state]
  (open) {Open};
\node[state,right=of open]
  (alarm) {Alarm};
\node[state,right=of alarm]
  (s1) {S1};
\node[state,above=of alarm,xshift=10pt]
  (reset) {Reset};
\node[state,below=of alarm,xshift=10pt]
  (s2) {S2};
\node[left=of reset,align=right,yshift=20pt]
  (resetany) {Reset input\\ (from any state)};
\draw[-triangle 45]
  (resetany.east) -- (reset);

\draw[midarr={right=2pt}{1}]
  (s2) -- (alarm);  
\draw[midarr={right=2pt}{0}]
  (reset) -- (alarm);  
\draw[midarr={below=1pt}{0}]
  (s1) -- (alarm);  
\draw[midarr={below left}{0}]
  (s2) to[bend left] (open);  
\draw[midarr={above left}{0}]
  (open) to[bend left] (reset);  
\draw[midarr={above right}{1}]
  (reset) to[bend left] (s1);  
\draw[midarr={below right}{1}]
  (s1) to[bend left] (s2);
\draw[midarr={left}{$0,1$}]
  (alarm) to[out=230,in=130,looseness=2.5] (alarm);
\draw[midarr={left}{1}]
  (open) to[out=230,in=130,looseness=2.5] (open);
\end{tikzpicture}

\end{document}

有一种initial样式（参考文档），但我选择了一种\node具有一些属性的简单样式来放置“重置输入（从任何状态）”文本。

这是问题代码的修改版本，使用与以前相同的想法：

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{automata,decorations.markings,positioning,arrows}

\begin{document}

\begin{tikzpicture}[
midarr/.style 2 args={
  decoration={
    markings,
    mark=at position 0.5 with {\arrow[xshift=3.333pt]{stealth'} \node[#1] {#2};},
  },
    postaction=decorate,
},
state/.append style={minimum size=35pt},
node distance=1.6cm and 1.6cm,
semithick,
>=stealth',
shorten >=1pt
]
\node[state]
  at (0,0)
  (alarm) {Alarm};
\node[state,left=of alarm]
  (open) {Open};
\node[state]
  at (45:2.8cm)
  (s1) {S1};
\node[state,right=of alarm]
  (s2) {S2};
\node[state,above=of alarm]
  (reset) {Reset};
\node[state]
  at (-45:2.8cm)
  (s3) {S3};
\node[state,below=of alarm]
  (s4) {S4};

\draw[midarr={right=2pt}{0}]
  (reset) -- (alarm);  
\draw[midarr={below right=1pt}{1}]
  (s1) -- (alarm);  
\draw[midarr={below=1pt}{0}]
  (s2) -- (alarm);  
\draw[midarr={below left}{0}]
  (s3) -- (alarm);  
\draw[midarr={left=2pt}{1}]
  (s4) -- (alarm);  
\draw[midarr={below left}{0}]
  (s4) to[bend left] (open);  
\draw[midarr={above left}{0}]
  (open) to[bend left] (reset);  
\draw[midarr={above right}{1}]
  (reset) to[out=0,in=132] (s1);  
\draw[midarr={right=2pt}{0}]
  (s1) to[out=-45,in=90] (s2);  
\draw[midarr={right=2pt}{1}]
  (s2) to[out=-90,in=45] (s3);  
\draw[midarr={below right}{1}]
  (s3) to[out=-135,in=0] (s4);  
\draw[midarr={left}{$0,1$}]
  (alarm) to[out=230,in=130,looseness=2.5] (alarm);
\draw[midarr={left}{1}]
  (open) to[out=230,in=130,looseness=2.5] (open);

\node[left=of reset,align=right,yshift=30pt,xshift=10pt]
  (resetany) {Reset input\\ (from any state)};
\draw[-stealth']
  (resetany.east) -- (reset);
\end{tikzpicture}

\end{document}