tikz：在間諜之上繪製

Question

我想在 tikz-spy 上畫畫，新行應該是覆蓋那些被間諜複製的。例如：

\documentclass{standalone}

\usepackage{tikz}
\usetikzlibrary{spy,shapes}

\pgfdeclarelayer{bg}    % declare background layer
\pgfsetlayers{bg,main}  % set the order of the layers (main is the standard layer)


\begin{document}
\begin{tikzpicture}[spy using outlines={rectangle, width=4.5cm, height=3cm, magnification=4, connect spies,every spy on node/.append style={thin}},hide/.style={opacity=1}]

\begin{scope}
    \draw  circle (8) node[yshift=8.8cm,align=center] {};
    \draw  circle (8.2) node {};
    \draw (-5,7.4) -- (5,7.4);
\end{scope}

%\begin{pgfonlayer}{bg}    % select the background layer
\spy [black] on (-3.4,7.4) in node (spyleft) [left] at (-0.5,4.5);
%\end{pgfonlayer}

%\begin{pgfonlayer}{main}    % select the main layer
\draw[line width=2pt,color=blue] (-3.3,4.5) -- (-1.35,4.5) -- (-1.35,5.35) -- cycle;
%\end{pgfonlayer}

\end{tikzpicture}

\end{document}

黑色線條上方應有藍色三角形。明確地將繪圖的各個部分放入圖層中似乎沒有幫助。是否有我可以解決的特定間諜層？

（理想情況下，我還希望三角形的角由圓和線的交點來定義，但現在我很樂意手動定位它，只要我能得到正確的圖層...）

Answer 1

聲明一個前景圖層並將藍色三角形放在該圖層上。

\documentclass{standalone}

\usepackage{tikz}
\usetikzlibrary{spy,shapes}

\pgfdeclarelayer{fg}    % declare foreground layer
\pgfsetlayers{main,fg}  % set the order of the layers (main is the standard layer)


\begin{document}
\begin{tikzpicture}[spy using outlines={rectangle, width=4.5cm, height=3cm, magnification=4, connect spies,every spy on node/.append style={thin}},hide/.style={opacity=1}]

  \begin{scope}
      \draw  circle (8) node[yshift=8.8cm,align=center] {};
      \draw  circle (8.2) node {};
      \draw (-5,7.4) -- (5,7.4);
  \end{scope}
  
  \spy [black] on (-3.4,7.4) in node (spyleft) [left] at (-0.5,4.5);
  
  \begin{pgfonlayer}{fg}    % select the main layer
    \draw[line width=2pt,blue] (-3.3,4.5) -- (-1.35,4.5) -- (-1.35,5.35) -- cycle;
  \end{pgfonlayer}
\end{tikzpicture}

\end{document}