Boolean test for whether float has been moved?

Question

Is it possible to create a boolean that knows whether or not a float remains inline, or has been moved?

In my case, the float will be a raster image of known size. Sometimes it will fit inline where the code is written, and sometimes it will float to the top of the following page. There are no other situations. Single column, two-sided only. I compile with LuaLaTeX in a custom document class, but I can illustrate my question more simply. In this MWE I used \@float to make it independent of any particular packages:

\documentclass{article}
\newif \ifthisthingmoved % true if float is moved away from ordinary inline
\makeatletter
\def\ftype@figure{0} % not sure why, but seems to be necessary
\setlength\intextsep{0pt}
\setlength\textfloatsep{0pt}
\setlength\floatsep{0pt}
\newenvironment{fitme}
{\@float{figure}[!ht]}
{\end@float\par}
\makeatother
\usepackage{lipsum}
\begin{document}
\lipsum[1-4] % vary the number of paragraphs
\begin{fitme}
% Here is where I wish to test \ifthisthingmoved.
\rule{200pt}{200pt}
\end{fitme}
\lipsum
\end{document}

In the above, with the values shown, the rule will be moved to the second page. So, I would like \ifthisthingmoved to be true (then I will do something with it). I assume that the first page is shipped before the moved object is positioned on the second page, so (hopefully) the asynchronous layout won't be a problem.

Answer 1

The following uses the \label-\ref system to store the pages of where the fitme environment is placed and where it ends up. If the page numbers of these two labels are the same, it is assumed the float didn't move.

\documentclass{article}

\usepackage{refcount}
\usepackage{lipsum}

\newcounter{moved}

\newif\ifthisthingmoved % true if float is moved away from ordinary inline
\newcommand{\movedtrue}{\let\ifthisthingmoved\iftrue}
\newcommand{\movedfalse}{\let\ifthisthingmoved\iffalse}

\newenvironment{fitme}
  {\stepcounter{moved}%
   \label{moved-start-\themoved}%
   \begin{figure}[!ht]%
     \label{moved-end-\themoved}
     \ifnum\getpagerefnumber{moved-start-\themoved}=\getpagerefnumber{moved-end-\themoved}
       \movedfalse
     \else
       \movedtrue
     \fi}
     }
  {\end{figure}}

\begin{document}

\lipsum[1-4] % vary the number of paragraphs

\begin{fitme}
  \ifthisthingmoved
    Moving along \ldots !
  \fi

  \rule{200pt}{200pt}
\end{fitme}

\lipsum

\end{document}

The conditional could be simplified somewhat by using this:

\newcommand{\ifthisthingstayed}{%
  \ifnum\getpagerefnumber{moved-start-\themoved}=\getpagerefnumber{moved-end-\themoved}}
\newcommand{\ifthisthingmoved}{\ifthisthingstayed\else}

However, this would not allow for using

\ifthisthingmoved
  % <this thing moved>
\else
  % <this thing did not move>
\fi

However, this did not seem a requirement from the original question.

---

This could probably be expanded to check the location on the current page (using \pdflastypos or zref's savepos module) if the page numbers were the same, in order to establish whether the float moved on the place it was placed (to the [t]op or [b]ottom).