为何忽略西北锚点？

Question

在下面的代码片段中，我期望节点垂直对齐。但看起来锚点被忽略了。

\documentclass{article}
\usepackage{graphicx}
\usepackage{tikz}
\usetikzlibrary{positioning,matrix}
\newcommand{\imgwidth}{2cm}
\begin{document}
    \begin{tikzpicture}
      \node[inner sep=5, draw, rectangle] (baz) {\includegraphics[height=\imgwidth,width=\imgwidth]{example-grid-100x100pt}};
%
      \node[inner sep=5, draw, rectangle, anchor=north west, below=of baz.south west] (bar)
      {\includegraphics[width=\imgwidth,height=\imgwidth]{example-grid-100x100pt}};
%
      \node[inner sep=5, draw, rectangle, anchor=north west, below=of bar.south west] (foo)
      {\includegraphics[width=\imgwidth,height=\imgwidth]{example-grid-100x100pt}};
    \end{tikzpicture}
\end{document}

为什么布局中不使用锚点？

Answer 1

正如我在评论中提到的，锚点必须位于节点选项的最后一个位置（稍微缩短的代码）：

\documentclass{article}
\usepackage{graphicx}
\usepackage{tikz}
\usetikzlibrary{positioning,matrix}
\newcommand{\imgwidth}{2cm}
\begin{document}
    \begin{tikzpicture}[every node/.style={rectangle, draw, inner sep=5}]
      \node (baz) 
      {\includegraphics[height=\imgwidth,width=\imgwidth]{example-grid-100x100pt}};
%
      \node[below=of baz.south west, anchor=north west] (bar)
      {\includegraphics[width=\imgwidth,height=\imgwidth]{example-grid-100x100pt}};
%
      \node[below=of bar.south west,anchor=north west] (foo)
      {\includegraphics[width=\imgwidth,height=\imgwidth]{example-grid-100x100pt}};
    \end{tikzpicture}
\end{document}

但是，使用更简单的代码就可以获得相同的结果：

\documentclass{article}
\usepackage{graphicx}
\usepackage{tikz}
\usetikzlibrary{positioning}
\newcommand{\imgwidth}{2cm}
\begin{document}
    \begin{tikzpicture}[every node/.style={rectangle, draw, inner sep=5}]
      \node (baz) {\includegraphics[height=\imgwidth,width=\imgwidth]{example-grid-100x100pt}};
%
      \node[below=of baz] (bar)
      {\includegraphics[width=\imgwidth,height=\imgwidth]{example-grid-100x100pt}};
%
      \node[below=of bar] (foo)
      {\includegraphics[width=\imgwidth,height=\imgwidth]{example-grid-100x100pt}};
    \end{tikzpicture}
\end{document}