Tikz 网格不使用 tikzpicture 单位长度

Question 1

根据手册，网格是按照/tikz/step=h手册中所述的配置步骤绘制a number or dimension or coordinate的(no default, initially 1cm)。

因此，如果您希望网格不以 1cm 为单位绘制，则必须更改step，如（或本地，仅针对网格绘制命令）：

\documentclass{article}
\usepackage{tikz}

\begin{document}

\begin{tikzpicture}
    \draw[very thick] (-2,-2) rectangle (2,2);
    \draw (-2,-2) grid (2,2);
    \fill (1,1) circle [radius=3pt];
\end{tikzpicture}


\begin{tikzpicture}[x=0.5cm,y=0.5cm,step=0.5cm]
    \draw[very thick] (-2,-2) rectangle (2,2);
    \draw (-2,-2) grid (2,2);
    \fill (1,1) circle [radius=3pt];
\end{tikzpicture}

\end{document}

Answer

根据手册，网格是按照/tikz/step=h手册中所述的配置步骤绘制a number or dimension or coordinate的(no default, initially 1cm)。

因此，如果您希望网格不以 1cm 为单位绘制，则必须更改step，如（或本地，仅针对网格绘制命令）：

\documentclass{article}
\usepackage{tikz}

\begin{document}

\begin{tikzpicture}
    \draw[very thick] (-2,-2) rectangle (2,2);
    \draw (-2,-2) grid (2,2);
    \fill (1,1) circle [radius=3pt];
\end{tikzpicture}


\begin{tikzpicture}[x=0.5cm,y=0.5cm,step=0.5cm]
    \draw[very thick] (-2,-2) rectangle (2,2);
    \draw (-2,-2) grid (2,2);
    \fill (1,1) circle [radius=3pt];
\end{tikzpicture}

\end{document}

Question 2

xstep网格分离由和控制，ystep它们分别将值存储在\tikz@grid@x和中\tikz@grid@y。它们的初始值定义为tikz.code.tex

\def\tikz@grid@x{1cm}%
\def\tikz@grid@y{1cm}%

在您的第二个示例中，您设置了x=0.5cm, y=0.5cm，这意味着(-2, -2)被解析为(-1cm, -1cm)并且(2, 2)被解析为(1cm, 1cm)。这是因为当将 coordinates 传递给 parse 时，首先检查 x 和 y 坐标是否以为单位\tikz@checkunit。然后 tikz 可以判断它是否以为单位\iftikz@isdimension，如果不是，则坐标设置为\pgfpointxy，否则坐标设置为\pgfpoint。实际上有四种情况需要处理，相关代码是

\def\tikz@@@parse@regular#1#2#3){%
  \pgfutil@in@,{#3}%
  \ifpgfutil@in@%
    \tikz@parse@splitxyz{#1}{#2}#3,%
  \else%
    \tikz@checkunit{#2}%
    \iftikz@isdimension%
      \tikz@checkunit{#3}%
      \iftikz@isdimension%
        \def\pgfutil@next{#1{\pgfpoint{#2}{#3}}}%
      \else%
        \def\pgfutil@next{#1{\pgfpointadd{\pgfpoint{#2}{0pt}}{\pgfpointxy{0}{#3}}}}%
      \fi%
    \else%
      \tikz@checkunit{#3}%
      \iftikz@isdimension%
        \def\pgfutil@next{#1{\pgfpointadd{\pgfpoint{0pt}{#3}}{\pgfpointxy{#2}{0}}}}%
      \else%
        \def\pgfutil@next{#1{\pgfpointxy{#2}{#3}}}%
      \fi%
    \fi%
  \fi%
  \pgfutil@next%
}%

类似的解析机制也适用xstep于ystep

    \tikz@checkunit{\tikz@grid@x}%
    \iftikz@isdimension%
      \pgf@process{\pgfpoint{\tikz@grid@x}{0pt}}%
    \else%
      \pgf@process{\pgfpointxy{\tikz@grid@x}{0}}%
    \fi%
    \pgf@xb=\pgf@x%
    \pgf@yb=\pgf@y%
    \tikz@checkunit{\tikz@grid@y}%
    \iftikz@isdimension%
      \pgf@process{\pgfpoint{0pt}{\tikz@grid@y}}%
    \else%
      \pgf@process{\pgfpointxy{0}{\tikz@grid@y}}%
    \fi%
    \advance\pgf@xb by\pgf@x%
    \advance\pgf@yb by\pgf@y%
    \pgfpathgrid[stepx=\pgf@xb,stepy=\pgf@yb]%
      {\pgfqpoint{\pgf@xa}{\pgf@ya}}{\pgfqpoint{\tikz@lastx}{\tikz@lasty}}%

在您的示例中，它们只是1cm，因此可以通过

\draw (-1cm, -1cm) grid (1cm, 1cm);

并且\fill (1, 1) circle [radius=3pt];等于\fill (0.5cm, 0.5cm) circle (3pt);不在任何网格点上。

Answer