Tikz：路径生成大片空白

Question

让我们假设以下情况（这是我能想到的最简单的情况）：一个圆与一条线的两个不同点相交，我们将这些点称为 C 和 D。

\documentclass[a4paper, 10pt]{article}
    \usepackage{tikz}
    \usetikzlibrary{intersections}
\begin{document}
And here we've got a text about whatever it's talking about and probably is introducing this:
    
    \begin{figure}[h!]
    \centering
        \begin{tikzpicture}
        \coordinate (A) at (-2,0);
        \coordinate (B) at (2,0);
        \coordinate (P) at (0,1);
        \draw [name path=line] (A)--(B);
        \draw [name path=circle] (P) circle (1.5cm);
        \path [name intersections ={of=line and circle,name=N,total=\t}];
        \node at (N-1)[below left]{C};
        \node at (N-2)[below right]{D};
        \end{tikzpicture}
    \end{figure}

Which lead us to the meaning of the figure.
\end{document}

我的情况实际上使用了 through 库，在示例中，就像给出线的一个点（C 或 D）并从 P 处通过该点绘制一个圆。我真的不知道它是否能改变问题。问题是：如果我只想要坐标怎么办？我不会使用 \draw，而是使用 \path（或 \node at (?) [circle through (...)];）和任何命令来简单地获取坐标。在示例中，我只是切换\draw [name path=circle] (P) circle (1.5cm);到\path [name path=circle] (P) circle (1.5cm);

\documentclass[a4paper, 10pt]{article}
    \usepackage{tikz}
    \usetikzlibrary{intersections}
\begin{document}
And here we've got a text about whatever it's talking about and probably is introducing this:
    
    \begin{figure}[h!]
    \centering
        \begin{tikzpicture}
        \coordinate (A) at (-2,0);
        \coordinate (B) at (2,0);
        \coordinate (P) at (0,1);
        \draw [name path=line] (A)--(B);
        \path [name path=circle] (P) circle (1.5cm);
        \path [name intersections ={of=line and circle,name=N,total=\t}];
        \node at (N-1)[below left]{C};
        \node at (N-2)[below right]{D};
        \end{tikzpicture}
    \end{figure}

Which lead us to the meaning of the figure.
\end{document}

这个巨大的空白区域。如何消除它才能得到如下效果：

顺便说一下，对于最后一幅图像，我只是输入了 C 和 D 坐标作为它们两个实际 X 坐标的近似值。

Answer 1

即使没有绘制路径，它们仍会对边界框产生影响。因此，您可能需要overlay在辅助路径和坐标上使用键。overlay确保它们不会对边界框产生影响。

\documentclass[a4paper, 10pt]{article}
\usepackage{tikz}
\usetikzlibrary{intersections}
\begin{document}
And here we've got a text about whatever it's talking about and probably is introducing this:
    
    \begin{figure}[h!]
    \centering
        \begin{tikzpicture}
        \path (-2,0) coordinate (A) (2,0) coordinate (B);
        \path[overlay] (0,1) coordinate (P);
        \draw [name path=line] (A)--(B);
        \path[overlay,name path=circle] (P) circle[radius=1.5cm];
        \path [name intersections ={of=line and circle,name=N}];
        \node at (N-1)[below left]{C};
        \node at (N-2)[below right]{D};
        \end{tikzpicture}
    \end{figure}

Which lead us to the meaning of the figure.
\end{document}

Answer 2

另一种方法是重置边界框并重新创建它以仅包含特定节点和范围（使用本地边界框）。

\documentclass[a4paper, 10pt]{article}
    \usepackage{tikz}
    \usetikzlibrary{intersections,fit}
\begin{document}
And here we've got a text about whatever it's talking about and probably is introducing this:
    
    \begin{figure}[h!]
    \centering
        \begin{tikzpicture}
        \coordinate (A) at (-2,0);
        \coordinate (B) at (2,0);
        \coordinate (P) at (0,1);
        \draw [name path=line] (A)--(B);
        \path [name path=circle] (P) circle (1.5cm);
        \path [name intersections ={of=line and circle,name=N,total=\t}];
        \node (C) at (N-1)[below left]{C};
        \node (D) at (N-2)[below right]{D};
        \pgfresetboundingbox
        \node[fit=(A) (B) (C) (D)] {};
        \draw[red] (current bounding box.south west) rectangle (current bounding box.north east);
        \end{tikzpicture}
    \end{figure}

Which lead us to the meaning of the figure.
\end{document}