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找到 TikZ 图片中某个点相对于独立包绘制的边框的坐标

tag-icon • tag-icon tikz-pgf standalone tikz-node coordinates
找到 TikZ 图片中某个点相对于独立包绘制的边框的坐标

考虑一个 TikZ 图片，其中有一个圆在 TikZ 坐标系中以 (0,0) 为中心。节点周围是一个复杂的形状，例如如下所示的曲线。在包中standalone，边框经过计算以自动贴合图片内容。

编译时是否可以输出standalone坐标系中（0,0）的最终坐标？

最小工作示例

以下代码片段生成了下图的简化版本。

\documentclass{standalone}
\usepackage{tikz}
\begin{document}
\begin{tikzpicture}
\coordinate (c1) at (0,0);
\coordinate (c2) at (-2, 0.2);
\node[circle,inner sep=2pt,draw=none,fill=red] at (c1) {};
\draw[color=blue,bend left=150] (c1) to (c2);
\end{tikzpicture}
\end{document}

在此处输入图片描述

答案1

节点中心的坐标（在 处(0,0)）将保持不变。但您可以提取边界框的坐标（如果使用包，则与输出格式相同standalone），并使用这些坐标来计算节点中心与每条边的距离。

您可以使用虚拟节点current bounding box及其锚点north east并south west结合\pgfgetlastxy获取当前边界框的坐标（south west但您可能只需要）：

\path (current bounding box.north east); 
\pgfgetlastxy{\boundingboxeast}{\boundingboxnorth} 
\path (current bounding box.south west); 
\pgfgetlastxy{\boundingboxwest}{\boundingboxsouth}

以下代码将打印(current bounding box.south west) is at (-77.49pt,-13.25343pt).到日志中：

\documentclass{standalone}
\usepackage{tikz}

\begin{document}
\begin{tikzpicture}

\coordinate (c1) at (0,0);
\coordinate (c2) at (-2, 0.2);
\node[circle,inner sep=2pt,draw=none,fill=red] at (c1) {};
\draw[color=blue,bend left=150] (c1) to (c2);

\path (current bounding box.south west); 
\pgfgetlastxy{\boundingboxwest}{\boundingboxsouth}
\message{(current bounding box.south west) is at (\boundingboxwest,\boundingboxsouth).}

\end{tikzpicture}
\end{document}

您可以创建一个这样的自定义辅助宏：

\documentclass{standalone}
\usepackage{tikz}

\NewDocumentCommand{\whereiscoordinate}{m}{
    \path (current bounding box.south west); 
    \pgfgetlastxy{\currentboundingboxwest}{\currentboundingboxsouth}
    \path #1; 
    \pgfgetlastxy{\currentcoordinatex}{\currentcoordinatey}
    \pgfmathsetmacro{\currentcoordinatedistancex}
        {-1*\currentboundingboxwest+\currentcoordinatex}
    \pgfmathsetmacro{\currentcoordinatedistancey}
        {-1*\currentboundingboxsouth+\currentcoordinatey}
    \message{Coordinate #1 
        is \currentcoordinatedistancex pt from the left and  
        \currentcoordinatedistancey pt from the bottom
        of the current bounding box. ^^J}
}

\begin{document}
\begin{tikzpicture}

\coordinate (c1) at (0,0);
\coordinate (c2) at (-2, 0.2);
\node[circle,inner sep=2pt,draw=none,fill=red] at (c1) {};
\draw[color=blue,bend left=150] (c1) to (c2);

\whereiscoordinate{(0,0)}
% prints to the log:
% Coordinate (0,0) is 77.49pt from the left and 13.25343pt from the bottom 
% of the current bounding box.

\whereiscoordinate{(-2,0.2)}
% prints to the log:
% Coordinate (-2,0.2) is 20.58452pt from the left and 18.9439pt from the bottom 
% of the current bounding box.

\end{tikzpicture}
\end{document}

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