Format reference and subref of subcaption

Question

Is it possible to format the \ref and \subref of a subcaption completely independently?

The manual suggests changing thesubfigure to change the the label of a subfigure and hence the output of \ref, but then this affect \subref as well.

For example, the following MWE

\documentclass{article}
\usepackage{subcaption}
\usepackage{cleveref}
\usepackage{tikz}

% and example figure
\def\exfigure#1#2{
  \begin{subfigure}[b]{0.3\linewidth}
    \centering
    \begin{tikzpicture}\path[draw=#1,fill=#1!20] (0,0) rectangle
      (4,4);\end{tikzpicture}
    \renewcommand{\thesubfigure}{#1}%
    \phantomsubcaption%
    \label{#2}%
  \end{subfigure}\hfill}

\DeclareCaptionLabelFormat{subreffig}{(\emph{#2})}
\captionsetup{subrefformat=subreffig}

\begin{document}
\begin{figure}
  \exfigure{red}{subfig1}
  \exfigure{green}{subfig2}
  \exfigure{blue}{subfig3}
  \caption{Three squares. Left: \subref{subfig1}. Center: \subref{subfig2}.
    Right: \subref{subfig3}.}
  \label{fig:all}
\end{figure}

In \cref{fig:all}, we have three subfigures \cref{subfig1}
\cref{subfig2} and \cref{subfig3}.
\end{document}

The figure has the following caption

Figure 1: Three squares. Left: (red). Center: (green). Right: (blue).

This is the output I am after. However, the text afterwards has

In fig. 1, we have three subfigures fig. 1red fig. 1green and fig. 1blue.

Is it possible to change it to

In fig. 1, we have three subfigures fig. 1-[red] fig. 1-[green] and fig. 1-[blue].

Changing the definition of \thesubfigure to

\renewcommand{\thesubfigure}{-[#1]}%

gives the correct output in text, but the wrong output in the caption.

Answer 1

I was able to get it to work without cleveref. Both subcaption and cleveref (not to mention hyperref) modify \label in many ways, producing a legion of \newlabel commands in the aux file. So I went back to basics and used \protected@write instead.

\documentclass{article}
\usepackage{subcaption}
%\usepackage{cleveref}
\usepackage{tikz}

\makeatletter
\newcommand{\sublabel}[1]{\refstepcounter{subfigure}%
  \protected@write\@auxout{}{\string\newlabel{sub@#1}{{(\string\emph{\thesubfigure})}{\thepage}}}%
  \protected@write\@auxout{}{\string\newlabel{#1}{{\thefigure-[\thesubfigure]}{\thepage}}}}
\makeatother

% and example figure
\def\exfigure#1#2{
  \begin{subfigure}[b]{0.3\linewidth}
    \centering
    \begin{tikzpicture}\path[draw=#1,fill=#1!20] (0,0) rectangle
      (4,4);\end{tikzpicture}
    \renewcommand{\thesubfigure}{#1}%
    \sublabel{#2}%
  \end{subfigure}\hfill}

\begin{document}
\begin{figure}
  \exfigure{red}{subfig1}
  \exfigure{green}{subfig2}
  \exfigure{blue}{subfig3}
  \caption{Three squares. Left: \subref{subfig1}. Center: \subref{subfig2}.
    Right: \subref{subfig3}.}
  \label{fig:all}
\end{figure}

In \ref{fig:all}, we have three subfigures \ref{subfig1}
\ref{subfig2} and \ref{subfig3}.
\end{document}

---

This version is compatible to both cleveref and hyperref. The key is to format \thesubfigure for \cref and \@currentlabel for \ref and \subref.

\documentclass{article}
\usepackage{tikz}
\usepackage{subcaption}
\usepackage{hyperref}
\usepackage{cleveref}

\makeatletter
\newcommand{\sublabel}[2]{% #1 = color, #2 = label
  \refstepcounter{subfigure}%
  \edef\@currentlabel{(\noexpand\emph{#1})}\nosublabel{sub@#2}%
  \edef\@currentlabel{\thefigure-[#1]}\nosublabel{#2}%
  \ignorespaces}
\makeatother

% and example figure
\def\exfigure#1#2{\let\nosublabel=\label
  \begin{subfigure}[b]{0.3\linewidth}
    \centering
    \begin{tikzpicture}\path[draw=#1,fill=#1!20] (0,0) rectangle
      (4,4);\end{tikzpicture}
    \renewcommand{\thesubfigure}{-[#1]}% for cref
    \sublabel{#1}{#2}
  \end{subfigure}\hfill}

\begin{document}
\begin{figure}
  \exfigure{red}{subfig1}
  \exfigure{green}{subfig2}
  \exfigure{blue}{subfig3}
  \caption{Three squares. Left: \subref{subfig1}. Center: \subref{subfig2}.
    Right: \subref{subfig3}.}
  \label{fig:all}
\end{figure}

In \cref{fig:all}, we have three subfigures \cref{subfig1}
\cref{subfig2} and \cref{subfig3}.
\end{document}

\begin{document}
\begin{figure}
  \exfigure{red}{subfig1}
  \exfigure{green}{subfig2}
  \exfigure{blue}{subfig3}
  \caption{Three squares. Left: \subref{subfig1}. Center: \subref{subfig2}.
    Right: \subref{subfig3}.}
  \label{fig:all}
\end{figure}

In \cref{fig:all}, we have three subfigures \cref{subfig1}
\cref{subfig2} and \cref{subfig3}.
\end{document}

Answer 2

A possible solution based on the internals of subcaption

\documentclass{article}
\usepackage{subcaption}
\usepackage{cleveref}
\usepackage{tikz}

\newcommand{\thesubreffigure}{\thesubfigure}

\makeatletter
\renewcommand*\subcaption@@label[2]{%
  \@bsphack\begingroup
    \subcaption@ORI@label#1{#2}%
    \let\SK@\@gobbletwo
    \protected@edef\@currentlabel{\csname thesubref\@captype\endcsname}%
    \subcaption@ORI@label#1{sub@#2}%
  \endgroup\@esphack}
\makeatother

% and example figure
\def\exfigure#1#2{
  \begin{subfigure}[b]{0.3\linewidth}
    \centering
    \begin{tikzpicture}\path[draw=#1,fill=#1!20] (0,0) rectangle
      (4,4);\end{tikzpicture}
    % \renewcommand{\thesubfigure}{#1}
    %
    \renewcommand{\thesubfigure}{-[#1]}%
    \renewcommand{\thesubreffigure}{#1}%
    \phantomsubcaption%
    \label{#2}%
  \end{subfigure}\hfill}

\DeclareCaptionLabelFormat{subreffig}{(\emph{#2})}
\captionsetup{subrefformat=subreffig}

\begin{document}
\begin{figure}
  \exfigure{red}{subfig1}
  \exfigure{green}{subfig2}
  \exfigure{blue}{subfig3}
  \caption{Three squares. Left: \subref{subfig1}. Center: \subref{subfig2}.
    Right: \subref{subfig3}.}
  \label{fig:all}
\end{figure}

In \cref{fig:all}, we have three subfigures \cref{subfig1}
\cref{subfig2} and \cref{subfig3}.
\end{document}

Produces the correct output for both \cref and \subref. Unfortunately does not produce the correct label when setting a caption instead of using \phantomsubcaption.