How to make text masking background shape lines

Question

I want to draw a picture with some text masking the background shape lines. I tried with opacity but the fill is not very nature.

\documentclass[border=5mm, convert, usenames, dvipsnames]{standalone}
\usepackage{tikz}
\usetikzlibrary{shapes, positioning, calc, arrows.meta, fit}

\begin{document}
\begin{tikzpicture}
    \node [draw, rectangle, minimum width=2cm, minimum height=4cm] (a) {};
    \node [draw, rectangle, minimum width=2cm, minimum height=4cm, right = 1cm of a] (b) {};
    \draw [->, >=latex] (a) to node [above, fill, opacity=0.2,text opacity=1] {HelloWorld} (b);
\end{tikzpicture}
\end{document}

Yield the following

However what I want is like this

Forget the background color, i use some image editing tool to get this. What I want is that part of rectangle shape line dissolved behind the text. I tried to use backgrounds but it also don't work.

Is there a possible solution?

Answer 1

I think behind path is what you are looking for. With behind path option node contents is drawn behind the path where it is defined (see example on page 214). This way fill=white will cover the lines and the arrow is drawn over the text.

\documentclass[border=5mm, convert, usenames, dvipsnames]{standalone}
\usepackage{tikz}
\usetikzlibrary{shapes, positioning, calc, arrows.meta, fit}

\begin{document}
\begin{tikzpicture}
    \node [draw, rectangle, minimum width=2cm, minimum height=4cm] (a) {};
    \node [draw, rectangle, minimum width=2cm, minimum height=4cm, right = 1cm of a] (b) {};
    \draw [->, >=latex] (a) to node [above, fill=white, behind path] {HelloWorld} (b);
\end{tikzpicture}
\end{document}

Answer 2

From your comment I take you want to block out the node. One way to do that is based on save path, reverseclip and this answer.

\documentclass[convert, usenames, dvipsnames,border=3.14mm]{standalone}
\usepackage{tikz}
\usetikzlibrary{positioning}
\makeatletter % https://tex.stackexchange.com/a/38995/121799
\tikzset{
  use path/.code={\pgfsyssoftpath@setcurrentpath{#1}}
}
\makeatother
\tikzset{block out/.style={save path=\tmprotect}}% 
% https://tex.stackexchange.com/a/12033/121799
\tikzset{reverseclip/.style={insert path={([xshift=\pgflinewidth/2,yshift=\pgflinewidth/2,]current bounding box.north
        east) rectangle ([xshift=-\pgflinewidth/2,yshift=-\pgflinewidth/2]current bounding box.south west)}}}
\begin{document}
\begin{tikzpicture}
 \node [rectangle, minimum width=2cm, minimum height=4cm] (a) {};
 \node [rectangle, minimum width=2cm, minimum height=4cm, right = 1cm of a] (b) {};
 \draw [->, >=latex] (a) to node [above, block out] {HelloWorld} (b);   
 \clip[use path=\tmprotect,reverseclip]; 
 \draw (a.south west) rectangle (a.north east)
 (b.south west) rectangle (b.north east);
\end{tikzpicture}
\end{document}