如何设置相对于默认单位的圆角半径

Question

背景：当我绘制 时tikzpicture，我只使用默认单位（即，我没有指定任何单位，如\draw (0,0) -- (1,1);）。

问题：当选项中没有给出单位时[rounded corners = <value>]，TikZ似乎假设给定的长度以 表示pt，即与默认单位不同。下面的例子突出显示了这种现象。（这可能是由于[rounded corners]= [rounded corners = 4pt]？）

\documentclass[margin=1cm]{standalone}
    \usepackage{tikz}

\begin{document}
    \begin{tikzpicture}[very thick]
        \draw [help lines, black!10] (-.5,-.5) grid (7.5,3.5);

        \draw [rounded corners=1] (0,0) rectangle ++(3,3) node [midway] {\footnotesize\texttt{rounded corners=1}};

        \draw [rounded corners=1cm] (4,0) rectangle ++(3,3) node [midway] {\footnotesize\texttt{rounded corners=1cm}};
    \end{tikzpicture}
\end{document}

---

问题：我想将圆角半径指定为默认单位的倍数（不假设1 default unit = 1cm）。我该如何实现？

Answer 1

好吧，你总是可以将默认单位保存在宏中并写入rounded corners=<number>\macroname。或者你可以使用包装器样式定义来自动执行此操作。例如：

\documentclass[border=10pt,multi,tikz]{standalone}
\begin{document}
\tikzset{%
  ebo unit/.store in=\ebounit,
  ebo corners/.style={rounded corners=#1\ebounit},
}
\begin{tikzpicture}[very thick, ebo unit=cm]
  \draw [help lines, black!10] (-.5,-.5) grid (7.5,3.5);
  \draw [ebo corners=1] (0,0) rectangle ++(3,3) node [midway] {\footnotesize\texttt{rounded corners=1}};
  \draw [rounded corners=1cm] (4,0) rectangle ++(3,3) node [midway] {\footnotesize\texttt{rounded corners=1cm}};
  \begin{scope}[ebo unit=mm,blue]
    \draw [ebo corners=5] (0,0) ++(.25,.25) rectangle ++(3,3) node [midway] {\footnotesize\texttt{rounded corners=5}};
    \draw [rounded corners=5mm] (4,0) ++(.25,.25) rectangle ++(3,3) node [midway] {\footnotesize\texttt{rounded corners=5mm}};
  \end{scope}
  \begin{scope}[ebo unit=ex,green]
    \draw [ebo corners=8] (0,0) ++(-.25,-.25) rectangle ++(3,3) node [midway] {\footnotesize\texttt{rounded corners=8}};
    \draw [rounded corners=8ex] (4,0) ++(-.25,-.25) rectangle ++(3,3) node [midway] {\footnotesize\texttt{rounded corners=8ex}};
  \end{scope}
\end{tikzpicture}
\end{document}