different caption format when on float pages

Question

I have seen the possibilities of formatting captions with caption, but I can't find a variable indicating whether the float is on a floatpage of a textpage.

Is it possible to use automatically standard textsize in captions on floatpages, and a smaller textsize in captions on textpages?

If so, how?

If not, I would also accept a short explanation why.

\documentclass{book}
%\usepackage{caption} %might solve part of my problem
\usepackage{lipsum}
\usepackage{hyperref}

\begin{document}
\lipsum

\begin{figure}[htb]
\rule{10cm}{10cm}
\caption{caption should be small}
\label{fig:label1}
\end{figure}

\lipsum

\begin{figure}[p]
\rule{10cm}{10cm}
\caption{caption should be textsize}
\label{fig:label2}
\end{figure}

\listoffigures
\end{document}

A positive answer should also work with placement specifiers mixing p and [htb].

Answer 1

This is likely to be more trouble than it is worth. The placement algorithm needs to know the total size of each figure (including the caption) in advance, so they are assembled and stored in a queue before they are placed. I don't think there is any way to predict whether a figure will end up on a float page without reprogramming a large and very complex part of the kernel (even using a [p] placement specifier won't work because LaTeX may decide to ignore it).