如何使用 Tikz 的 fit 包含标签？

Question

我正在使用 TikZ 创建图表。它运行良好，但是当我尝试使用它fit来制作背景时，它不够大：

请注意，绿色没有覆盖标签 Gateway 和 Root。我认为如果有一种方法可以引用节点的标签（类似于我可以执行的方法node.north等），那么应该可以。

这是我正在使用的代码：

\documentclass{article}
\usepackage{tikz}
\begin{document}\usetikzlibrary{arrows,decorations.pathmorphing,backgrounds,positioning,fit,petri}

\begin{tikzpicture}
    [gateway/.style={circle, fill=blue!20!white, draw=blue, thick, inner sep=0pt,
                     minimum size=6mm, label=below:Gateway},
     root/.style={circle, fill=red!20!white, draw=red, thick, inner sep=0pt,
                  minimum size=6mm, label=below:Root},
     node/.style={circle, fill=gray!20!white, draw=gray, thick, inner sep=0pt,
                  minimum size=6mm, label=below:Node},
     every edge/.style={<->, semithick, draw}, 
     ]
    \node[gateway] (gateway_1) at ( 0, 0) {};
    \node[root]    (root_1)    at (10, 0) {};
    \node[node]    (node_1)    at ( 5, 5) {}
         edge node [auto] {connect} (root_1)
         edge (gateway_1);
    
    \begin{pgfonlayer}{background}
        \node [fill=green!20!white, fit=(gateway_1) (root_1) (node_1)]{};
    \end{pgfonlayer}
\end{tikzpicture}
\end{document}

所以当然正如标题所说，我如何在背景中包含标签？

谢谢！

Answer 1

来自 pgf 手册的相关信息，“建立边界框”部分

有一个节点可以让你获取当前边界框的大小。该current bounding box节点具有矩形形状，其大小始终是当前边界框的大小。

因此，您可以使用此节点的坐标来填充背景：

\documentclass{minimal}
\usepackage{tikz}
\usetikzlibrary{arrows,decorations.pathmorphing,backgrounds,positioning,fit,petri}

\begin{document}
\begin{tikzpicture}
    [gateway/.style={circle, fill=blue!20!white, draw=blue, thick, inner sep=0pt,
                     minimum size=6mm, label=below:Gateway},
     root/.style={circle, fill=red!20!white, draw=red, thick, inner sep=0pt,
                  minimum size=6mm, label=below:Root},
     node/.style={circle, fill=gray!20!white, draw=gray, thick, inner sep=0pt,
                  minimum size=6mm, label=below:Node},
     every edge/.style={<->, semithick, draw}, 
     ]
    \coordinate[gateway] (gateway_1) at ( 0, 0);
    \coordinate[root]    (root_1)    at (10, 0);
    \coordinate[node]    (node_1)    at ( 5, 5)
         edge node [auto] {connect} (root_1)
         edge (gateway_1);

    \begin{pgfonlayer}{background}
        \fill[green!20!white] (current bounding box.south west) rectangle
            (current bounding box.north east);
    \end{pgfonlayer}
\end{tikzpicture}
\end{document}

注意我还\node用对象替换了您的空对象\coordinate。坐标相当于节点，除了一些小细节，例如没有默认形状。坐标不包含文本，因此不需要一组空括号{}。

---

更新

这是一个更灵活的版本，它使用环境local bounding box参数scope仅为范围的内容计算边界框：

\begin{tikzpicture}
    [gateway/.style={circle, fill=blue!20!white, draw=blue, thick, inner sep=0pt,
                     minimum size=6mm, label=below:Gateway},
     root/.style={circle, fill=red!20!white, draw=red, thick, inner sep=0pt,
                  minimum size=6mm, label=below:Root},
     node/.style={circle, fill=gray!20!white, draw=gray, thick, inner sep=0pt,
                  minimum size=6mm, label=below:Node},
     every edge/.style={<->, semithick, draw},
     background fill/.store in=\bgfill,
     background fill=green!20!white,   % Default value
     fill background/.style={
       local bounding box=bbox,
       execute at end scope={
         \begin{pgfonlayer}{background}
           \coordinate[rectangle,fill=\bgfill,fit=(bbox)];
         \end{pgfonlayer}}
    }]

    \begin{scope}[fill background,background fill=red!20!white]
      \coordinate[gateway] (gateway_1) at ( 0, 0);
      \coordinate[root]    (root_1)    at (10, 0);
      \coordinate[node]    (node_1)    at ( 5, 5)
           edge node [auto] {connect} (root_1)
           edge (gateway_1);
    \end{scope}    

    \begin{scope}[fill background]
      \coordinate[gateway] (gateway_2) at ( 2.5, -2);
      \coordinate[node]    (node_2) at ( 7.5, -2)
           edge (gateway_2);
    \end{scope}    

\end{tikzpicture}

对于每个标有 的范围fill background，边界框都存储在名为 的节点中bbox。execute at end scope用于在范围结束时自动在背景层上创建填充。 键background fill设置为更改 的值，\bgfill以便可以自定义背景颜色。

结果是：