如何使用 TikZ 在箭头上方和下方添加文本？

Question

我正在尝试在箭头上方和下方添加文本，但我似乎无法找到一种方法来做到这一点，而无需在彼此之上创建两个箭头，这看起来很尴尬。

我现在所拥有的看起来有点像这样：

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

\begin{document}

\begin{tikzpicture} [node distance = 4cm, auto]
    \node (0) [state, initial] {$q_0$};
    \node (1) [state, right = of 0] {$q_1$};
    \node (2) [state, right = of 1] {$q_2$};

    \path [-stealth]
        (0) edge node {A} (1)
        (1) edge [loop above] node {B} (1)
        (1) edge node {sample text above arrow} (2);
\end{tikzpicture}

\end{document}

\end{tikzpicture}

我还希望能够在和sample text below arrow之间的同一边缘添加一些。(1)(2)

Answer 1

一个非常简单的解决方案（在您的代码之前测试过）如下：

代码：

\documentclass{article}

\usepackage{tikz}
\begin{document}
    \begin{tikzpicture}
        \draw[-latex,line width=2pt] (1,0)--(5,0) node[midway,above] () {above};
        \draw[-latex,line width=2pt] (1,0)--(5,0) node[midway,below] () {below};
        \draw[red,-latex,line width=2pt] (1,0)--(5,4) node[midway,above,sloped] () {above};
        \draw[red,-latex,line width=2pt] (1,0)--(5,4) node[midway,below,sloped] () {below};
        \draw[cyan,-latex,line width=2pt] (1,0) arc (-180:0:2) node[pos=.25,below,sloped] () {below};
        \draw[cyan,-latex,line width=2pt] (1,0) arc (-180:0:2) node[pos=.75,above,sloped] () {above};
    \end{tikzpicture}   
\end{document}

编辑：您还可以考虑这个解决方案：

\documentclass{article}

\usepackage{tikz}
\begin{document}
    \begin{tikzpicture}
        \draw[-latex,line width=2pt] (1,0)--(5,0)
        node[midway,above] {above}
        node[midway,below] {below};
    
        \draw[red,-latex,line width=2pt] (1,0)--(5,4)
        node[midway,above,sloped] {above}
        node[midway,below,sloped] {below};
        
        \draw[cyan,-latex,line width=2pt] (1,0) arc (-180:0:2)
        node[midway,below,sloped] {below}
        node[midway,above,sloped] {above};
    \end{tikzpicture}   
\end{document}

输出为：

Answer 2

您可以简单地使用选项添加另一个边缘节点below（参见@Qrrbrbirlbel 评论）或使用quotes库并编写您的 MWE（最小工作示例），如下所示：

\documentclass[margin=3mm]{standalone}
%\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{arrows.meta, automata,  
                positioning,
                quotes}

\begin{document}
    \begin{tikzpicture}[
node distance = 4cm, 
every edge quotes/.style = {auto, align=center}
                        ]
\node (0) [state, initial] {$q_0$};
\node (1) [state, right = of 0] {$q_1$};
\node (2) [state, right = of 1] {$q_2$};

\path[-Stealth]
        (0) edge["A"] (1)
        (1) edge[loop above, "B"] (1)
        (1) edge["sample text\\ above arrow", 
                 "sample text\\ below arrow" swap] (2); 
    \end{tikzpicture}
\end{document}

swap相反，您可以简要地写下选项'。