tikz-qtree 中的 fit 和/或背景无法按预期工作

Question

我正在使用 绘制一棵树tikz-qtree，想要绘制backgrounds两组节点：左边的组由 组成l, l1, l2，右边的组由 组成r, rl, l3, l4, l5。但是，如下图所示，节点c也在右侧背景矩形中。

如何绘制仅由 组成的背景矩形r, rl, l3, l4, l5？

\documentclass{standalone} 
\usepackage{tikz} 
\usepackage{tikz-qtree}
\usetikzlibrary{backgrounds, fit, shapes}

\begin{document}
\begin{tikzpicture}[level distance = 25pt, sibling distance = 15pt,   edge from parent/.style= {
      draw, edge from parent path = {(\tikzparentnode) -- (\tikzchildnode)}}]   \tikzset{every tree node/.style = {align = center, circle, draw, fill = red!40},
      leaf/.style = {fill = teal!40}}

      \Tree [.\node[](c){$c$}; 
              [.\node[](l){$l$}; 
                [.\node[leaf](l1){$l_1$}; ]
                [.\node[leaf](l2){$l_2$}; ]
              ]
              [.\node[](r){$r$};
                [.\node[](rl){$rl$};
                  [.\node[leaf](l3){$l_3$}; ] 
                  [.\node[leaf](l4){$l_4$}; ]
                ] 
                [.\node[leaf](l5){$l_5$}; ]
              ]       
      ]

      \node () [draw, dashed, cyan, rounded corners, fit = (l) (l1) (l2)] {};   
      \node () [draw, dashed, cyan, rounded corners, fit = (r) (rl) (l3) (l4) (l5)] {}; 
\end{tikzpicture} 
\end{document}

Answer 1

你只需要将节点命名为 以外的其他名称r。下面，我使用 ，3r没有什么特别的原因。

\documentclass[border=10pt]{standalone} 
\usepackage{tikz} 
\usepackage{tikz-qtree}
\usetikzlibrary{backgrounds, fit, shapes}

\begin{document}
\begin{tikzpicture}[level distance = 25pt, sibling distance = 15pt,   edge from parent/.style= {
    draw, edge from parent path = {(\tikzparentnode) -- (\tikzchildnode)}}]   \tikzset{every tree node/.style = {align = center, circle, draw, fill = red!40},
    leaf/.style = {fill = teal!40}}

  \Tree [.\node[](c){$c$}; 
  [.\node[](l){$l$}; 
  [.\node[leaf](l1){$l_1$}; ]
  [.\node[leaf](l2){$l_2$}; ]
  ]
  [.\node[](3r){$r$};
  [.\node[](rl){$rl$};
  [.\node[leaf](l3){$l_3$}; ] 
  [.\node[leaf](l4){$l_4$}; ]
  ] 
  [.\node[leaf](l5){$l_5$}; ]
  ]       
  ]

  \node () [draw, dashed, cyan, rounded corners, fit = (l) (l1) (l2)] {};   
  \node () [draw, dashed, cyan, rounded corners, fit = (3r) (rl) (l3) (l4) (l5)] {}; 
\end{tikzpicture} 
\end{document}

但是，我也不知道为什么。话虽如此，我猜这(r)是树的根，因为你可以使用这个节点而不需要命名任何东西r。例如，

\begin{tikzpicture}[level distance = 25pt, sibling distance = 15pt,   edge from parent/.style= {
    draw, edge from parent path = {(\tikzparentnode) -- (\tikzchildnode)}}]   \tikzset{every tree node/.style = {align = center, circle, draw, fill = red!40},
    leaf/.style = {fill = teal!40}}

  \Tree [.\node[](c){$c$}; 
  [.\node[](l){$l$}; 
  [.\node[leaf](l1){$l_1$}; ]
  [.\node[leaf](l2){$l_2$}; ]
  ]
  [.\node[](3r){$r$};
  [.\node[](rl){$rl$};
  [.\node[leaf](l3){$l_3$}; ] 
  [.\node[leaf](l4){$l_4$}; ]
  ] 
  [.\node[leaf](l5){$l_5$}; ]
  ]       
  ]

  \node () [draw, dashed, cyan, rounded corners, fit = (l) (l1) (l2)] {};   
  \node () [draw, dashed, cyan, rounded corners, fit = (3r) (rl) (l3) (l4) (l5)] {}; 
  \node () [draw, dashed, cyan, rounded corners, fit = (r) (rl) (l3) (l4) (l5)] {}; 
\end{tikzpicture} 

产生完全合理的（即使出乎意料）输出，而不是预期的错误：

这强烈建议r命名根节点，或者可能是树根处的坐标或不可见节点。

Answer 2

我不确定为什么会发生这种情况，但作为一种解决方法，您可以添加相对于(r)要使用的明确坐标：

\documentclass{standalone} 
\usepackage{tikz} 
\usepackage{tikz-qtree}
\usetikzlibrary{backgrounds, fit, shapes,calc}

\begin{document}
\begin{tikzpicture}[level distance = 25pt, sibling distance = 15pt,   edge from parent/.style= {
      draw, edge from parent path = {(\tikzparentnode) -- (\tikzchildnode)}}]   \tikzset{every tree node/.style = {align = center, circle, draw, fill = red!40},
      leaf/.style = {fill = teal!40}}

      \Tree [.\node[](c){$c$}; 
              [.\node[](l){$l$}; 
                [.\node[leaf](l1){$l_1$}; ]
                [.\node[leaf](l2){$l_2$}; ]
              ]
              [.\node[](r){$r$};
                [.\node[](rl){$rl$};
                  [.\node[leaf](l3){$l_3$}; ] 
                  [.\node[leaf](l4){$l_4$}; ]
                ] 
                [.\node[leaf](l5){$l_5$}; ]
              ]       
      ]
      \coordinate (rr) at ($(r)-(0,.6)$);
      \node () [draw, dashed, cyan, rounded corners, fit = (l) (l1) (l2)] {};   
      \node () [draw, dashed, cyan, rounded corners, fit =  (rr) (rl) (l3) (l4) (l5) ] {}; 
\end{tikzpicture} 
\end{document}