TikZ 多部分节点锚点不一致

Question

在下面的例子中，为什么节点锚点的位置不一致？

\input tikz
\usetikzlibrary{arrows,shapes.multipart}
\tikzset{
  font=\tt, >= stealth, every picture/.style={thick}, pointer/.style={*->},
  box/.style={draw, inner sep=2ex, fill=black!10, rounded corners,
    rectangle, rectangle split, rectangle split parts=2,
    rectangle split ignore empty parts=false, rectangle split horizontal}}
\tikzpicture[every node/.append style={at end}]
  \node[box] (1) {};
  \draw[pointer] (1.text) -- +(0,-1) node[anchor=north,box] (2) {};
  \draw[pointer] (2.text) -- +(0,-1) node[anchor=north] {1};
  \draw[pointer] (2.two) -- +(0,-1) node[anchor=north] {2};
  \draw[pointer] (1.two) -- +(1,0) node[anchor=base west,box] (3) {};
  \draw[pointer] (3.text) -- +(0,-1) node[anchor=north] {3};
  \draw[pointer] (3.two) -- +(0,-1) node[anchor=north] {4};
\endtikzpicture
\bye

理想情况下，我希望黑点正好位于中心。

Answer 1

我不确定你采取的方法是否正确。在 pgfmanual 中，你可以看到没有给出不同部分的中心。我认为某个部分（例如“一”）的中心是$(1.west)!.5!(1.one split)$。我快速编写了下一个代码，可以编写一些更优雅的代码。

更新版本 2：我找到了一种创建每个部分中心坐标的方法，但我找不到如何使用样式创建圆圈。（c1 3）设计节点第一部分的中心（3）。代码中有一些修改，例如at end

\input tikz
\usetikzlibrary{arrows,shapes.multipart,calc}

\tikzset{
  font=\tt, 
  >= stealth, 
  every picture/.style={thick},
  box/.style={at end,
              draw, 
              inner sep=2ex, 
              fill=black!10, 
              rounded corners,
              rectangle, 
              rectangle split, 
              rectangle split parts=2,
              rectangle split ignore empty parts=false, 
              rectangle split horizontal,
              append after command={%
              \pgfextra{%
                \let\mainnode=\tikzlastnode} 
                coordinate (c1 \mainnode) at ($(\mainnode.west)!.5!(\mainnode.one split)$)
                coordinate (c2 \mainnode) at ($(\mainnode.one split)!.5!(\mainnode.east)$)}}}
\tikzpicture
  \node[box] (1) {};
   \draw[->] (c1 1) -- +(0,-1) node[anchor=north,box] (2) {};
   \draw[->] (c1 2) -- +(0,-1) node[anchor=north] {1};
   \draw[->] (c2 2) -- +(0,-1) node[anchor=north] {2};
   \draw[->] (c2 1) -- +(1,0)  node[anchor=west,box] (3) {};
   \draw[->] (c1 3) -- +(0,-1) node[anchor=north] {3};
   \draw[->] (c2 3) -- +(0,-1) node[anchor=north] {4};  
   \foreach \i in {1,2,3}{\draw[fill=black] (c1 \i)circle(2pt) (c2 \i)circle(2pt);}
\endtikzpicture
\bye 

与 Marc 解决方案的区别

\node[box] (1) { };
\draw[] (1.one|-1.west) circle(2pt);
\draw[fill=black] ($(1.west)!.5!(1.one split)$)circle(2pt); 

给出

更新版本 3。可以直接绘制圆圈，但在这种情况下，您不能同时绘制箭头。代码很有趣，也许有人可以为箭头找到一个好主意（当我们使用时只有箭头box）

\input tikz
\usetikzlibrary{arrows,shapes.multipart,calc}

\tikzset{
  font=\tt, 
  >= stealth, 
  every picture/.style={thick},
  box/.style={
              draw, 
              inner sep=2ex, 
              fill=black!10, 
              rounded corners,
              rectangle, 
              rectangle split, 
              rectangle split parts=2,
              rectangle split ignore empty parts=false, 
              rectangle split horizontal,
              append after command={%
                \pgfextra{\let\mainnode=\tikzlastnode 
                \coordinate (c1 \mainnode) at ($(\mainnode.west)!.5!(\mainnode.one split)$);
                \coordinate (c2 \mainnode) at ($(\mainnode.one split)!.5!(\mainnode.east)$);
                \draw[fill=black] (c1 \mainnode)circle(2pt) (c2 \mainnode)circle(2pt);}
                }}}
\tikzpicture
   \node[box] (1) {};
   \path (c1 1)     -- +(0,-1) node[anchor=north,box] (2) {};
   \draw[->] (c1 2) -- +(0,-1) node[anchor=north] {1};
   \draw[->] (c2 2) -- +(0,-1) node[anchor=north] {2};
   \path (c2 1)     -- +(1,0)  node[anchor=west,box] (3) {};
   \draw[->] (c1 3) -- +(0,-1) node[anchor=north] {3};
   \draw[->] (c2 3) -- +(0,-1) node[anchor=north] {4};
   \draw[->] (c1 1) --  (2.north);
   \draw[->] (c2 1) --  (3.west); 
\endtikzpicture
\bye 

我们得到了相同的结果。

Answer 2

看起来这是一个错误。有两个原因。指针样式导致箭头的起始位置错误。除此之外，方框文本部分内的定位看起来也可疑。下面我将展示如何使用普通箭头并计算（看起来是）文本部分的中心来解决这些问题two。

\usetikzlibrary{calc}

\usetikzlibrary{arrows,shapes.multipart}
\begin{document}
\tikzset{
  font=\tt, >= stealth, every picture/.style={thick}, pointer/.style={*->},
  box/.style={draw, inner sep=2ex, fill=black!10, rounded corners,
    rectangle, rectangle split, rectangle split parts=2,
    rectangle split ignore empty parts=false, rectangle split horizontal}}
\tikzpicture[every node/.append style={at end}]
  \node[box] (1) {};
  \draw[->] (1.mid) -- +(0,-1) node[anchor=north,box] (2) {};
  \draw[->] (2.mid) -- +(0,-1) node[anchor=north] {1};
  \draw[->] (2.two|-2.east) -- +(0,-1) node[anchor=north] {2};
  \draw[->] (1.two|-1.east) -- +(1,0) node[anchor=base west,box] (3) {};
  \draw[->] (3.mid) -- +(0,-1) node[anchor=north] {3};
  \draw[->] (3.two|-3.east) -- +(0,-1) node[anchor=north] {4};
\endtikzpicture