TikZ overlay does not increase node size internally

Question

I was experimenting with the potential of a TikZ node to populate in it as many items as possible to make it intricate. Generally, the contents increase the node size when they exceed its minimum height and width.

However when I try to embed TikZ overlay on a graphic image inside the node (suppose), the overlay works fine, but its content does not seem to affect the size of the node to which it belongs as you can see in the following figure as compiled from the given MWE following the figure.

As you can see, the text 'sample 1' appears out of the node region when its presence was supposed to increase the region's area to contain it.

The reason I am using the node this way is because I am using this node as part of a larger diagram and would relate other pieces of the diagram with this node.

Hence, how can I make TikZ overlay force node to increase its size?

\documentclass{article}

\usepackage[margin=1in]{geometry}

\usepackage{tikz}
\usepackage{graphicx}
\usepackage{xcolor,colortbl,ctable}
\usepackage{lmodern}

\definecolor{DarkPink}{rgb}{0.82,0.445,0.668}
\definecolor{LightPink}{rgb}{0.91,0.80,0.863}
\definecolor{Pink}{rgb}{0.871,0.664,0.793}

\begin{document}

\begin{tikzpicture}
\node[gray,fill=gray!10!white,rectangle,draw,thick,densely dashed,rounded corners=10pt,minimum size=1cm,inner sep=10pt,font=\sffamily,align=center] at (0,0){
                \includegraphics[height=3cm,width=3cm]{example-grid-100x100pt}\\[10pt]
                \begin{tikzpicture}[remember picture, overlay]
                    \draw[red, ultra thick,densely dotted,rounded corners=0pt] (1.25,3.35) node[yshift=2cm](a){sample 1} rectangle (2.5,4.8);
                    \draw[blue, ultra thick,densely dotted,rounded corners=0pt] (2.65,4.7) rectangle (4.2,1.85);
                \end{tikzpicture}
                {\renewcommand{\arraystretch}{1.25}
                \begin{tabular}{!{\color{white}\vrule}c!{\color{white}\vrule}c!{\color{white}\vrule}}
                    \arrayrulecolor{white}\hline
                    \rowcolor{DarkPink}
                    \textcolor{white}{\textbf{Data Set 1}} & \textcolor{white}{\textbf{Data Set 2}}\\
                    \arrayrulecolor{white}
                    \rowcolor{LightPink}
                    \specialrule{2pt}{0pt}{0pt}
                    \color{black}80\% from $v_1$ & \color{black}20\% from $v_1$\\
                    \arrayrulecolor{white}\hline
                    \rowcolor{Pink}
                    \color{black}80\% from $v_2$ & \color{black}20\% from $v_2$\\
                    \arrayrulecolor{white}\hline
                    \rowcolor{LightPink}
                    \color{black}80\% from $v_3$ & \color{black}20\% from $v_3$\\
                    \arrayrulecolor{white}\hline
                    \rowcolor{Pink}
                    \color{black}80\% from $v_4$ & \color{black}20\% from $v_4$\\
                    \arrayrulecolor{white}\hline
                \end{tabular}}
            };
\end{tikzpicture}

\end{document}

Answer 1

In general, don't put a tikzpicture inside a node. See e.g. Proper nesting of tikzpicture environments: Reset all PGF values to their defaults

Perhaps you could place the components first and then draw the frame last, using the backgrounds library and its on background layer key. Or alternatively use a matrix to place the components. The dotted boxes are drawn using the corner of the node containing the image in both cases.

Not sure if these will work for your situation, but you can have a look at the examples below.

\documentclass{article}

\usepackage[margin=1in]{geometry}

\usepackage{tikz}
\usepackage{colortbl,ctable}
\usepackage{lmodern}
\usetikzlibrary{positioning, fit, backgrounds}

\definecolor{DarkPink}{rgb}{0.82,0.445,0.668}
\definecolor{LightPink}{rgb}{0.91,0.80,0.863}
\definecolor{Pink}{rgb}{0.871,0.664,0.793}

\begin{document}

\begin{tikzpicture}[font=\sffamily]
\node [inner sep=0] (img) {\includegraphics[height=3cm,width=3cm]{example-grid-100x100pt}};\\[10pt]

\node [below=2mm of img]{
                {\renewcommand{\arraystretch}{1.25}
                \begin{tabular}{!{\color{white}\vrule}c!{\color{white}\vrule}c!{\color{white}\vrule}}
                    \arrayrulecolor{white}\hline
                    \rowcolor{DarkPink}
                    \textcolor{white}{\textbf{Data Set 1}} & \textcolor{white}{\textbf{Data Set 2}}\\
                    \arrayrulecolor{white}
                    \rowcolor{LightPink}
                    \specialrule{2pt}{0pt}{0pt}
                    \color{black}80\% from $v_1$ & \color{black}20\% from $v_1$\\
                    \arrayrulecolor{white}\hline
                    \rowcolor{Pink}
                    \color{black}80\% from $v_2$ & \color{black}20\% from $v_2$\\
                    \arrayrulecolor{white}\hline
                    \rowcolor{LightPink}
                    \color{black}80\% from $v_3$ & \color{black}20\% from $v_3$\\
                    \arrayrulecolor{white}\hline
                    \rowcolor{Pink}
                    \color{black}80\% from $v_4$ & \color{black}20\% from $v_4$\\
                    \arrayrulecolor{white}\hline
                \end{tabular}}
            }; 
            
            \node [anchor=south west, red] at (img.north west) {Sample 1};
            \draw [red, densely dotted, thick] (img.north west) ++(3mm,-2pt) rectangle +(1cm,-1cm);
            \draw [blue, densely dotted, thick] (img.north west) ++(13mm,-4pt) rectangle +(1cm,-1.2cm);

% draw the frame box last 
\scoped[on background layer]            
   \node [fit=(current bounding box), gray,fill=gray!10!white,rectangle,draw,thick,densely dashed,rounded corners=10pt,minimum size=1cm,inner sep=5pt,font=\sffamily,align=center] {};            

\end{tikzpicture}


\begin{tikzpicture}

\matrix [
  every outer matrix/.style={
     gray,fill=gray!10!white, draw, thick,
     densely dashed, rounded corners=10pt,
     inner sep=5pt
   },
   font=\sffamily,align=center,
   ampersand replacement=\&]
{
\node [red] {Sample 1}; \\ 
\node [inner sep=0] (img) {\includegraphics[height=3cm,width=3cm]{example-grid-100x100pt}};\\
\node {
                {\renewcommand{\arraystretch}{1.25}
                \begin{tabular}{!{\color{white}\vrule}c!{\color{white}\vrule}c!{\color{white}\vrule}}
                    \arrayrulecolor{white}\hline
                    \rowcolor{DarkPink}
                    \textcolor{white}{\textbf{Data Set 1}} & \textcolor{white}{\textbf{Data Set 2}}\\
                    \arrayrulecolor{white}
                    \rowcolor{LightPink}
                    \specialrule{2pt}{0pt}{0pt}
                    \color{black}80\% from $v_1$ & \color{black}20\% from $v_1$\\
                    \arrayrulecolor{white}\hline
                    \rowcolor{Pink}
                    \color{black}80\% from $v_2$ & \color{black}20\% from $v_2$\\
                    \arrayrulecolor{white}\hline
                    \rowcolor{LightPink}
                    \color{black}80\% from $v_3$ & \color{black}20\% from $v_3$\\
                    \arrayrulecolor{white}\hline
                    \rowcolor{Pink}
                    \color{black}80\% from $v_4$ & \color{black}20\% from $v_4$\\
                    \arrayrulecolor{white}\hline
                \end{tabular}}
            }; \\ % end also the last row with \\
      };

       \draw [red, densely dotted, thick] (img.north west) ++(3mm,-2pt) rectangle +(1cm,-1cm);
       \draw [blue!50, densely dotted, thick] (img.north west) ++(14mm,-4pt) rectangle +(1cm,-1.2cm);
\end{tikzpicture}
\end{document}