使用扩展宏作为可选的环境参数

Question

我想打开一个环境，将宏的内容传递给可选参数。到目前为止，我尝试了使用 \expandafter 的不同方法，但我无法获得预期的行为。

\RequirePackage{graphicx}
\RequirePackage{xkeyval}

% In my original code I've got some key definition
% for [myStyle]{floating} at this place, I guess the real
% definition does not matter but would distract.

% Place an image within a floating environment and add caption
% and label automatically
\newcommand{\img}[2][]{
    \setkeys*{Gin}{#1}
    \setkeys[myStyle]{floating}{\XKV@rm}

    \begin{figure}[\XKV@myStyle@floating@placement@value]
        \includegraphics{#2}
        \caption{\XKV@myStyle@floating@caption@value}
        \label{fig:\XKV@myStyle@floating@label@value}
    \end{figure}
}

现在，当我尝试使用 \img 命令时，如下：

\img[caption = A picture, label = TheLabel, placement = h!]{mm-01-01}

图片已插入，它有标签和标题，但放置选项似乎被忽略了。

为什么？如何在不定义新环境的情况下解决这个问题？

完整代码如下：

\documentclass[
     paper = a4,
     fontsize = 11pt,
     index = totoc,
     listof = totoc,
     parskip
]{scrartcl}



\usepackage{xkeyval}
\usepackage{graphicx}
\usepackage{lipsum}



\makeatletter
% \parameter caption The caption of the item within the floating environment.
% If caption is empty, no caption will be placed.
\define@key[myStyle]{floating}{caption}[]{
    \PackageInfo{myStyle}{Setting caption to "#1"}
}

% \parameter label The label of the item within the floating environment.
% If label is empty, no label will be placed.
\define@key[myStyle]{floating}{label}[]{
     \PackageInfo{myStyle}{Setting label to "#1"}
}

% \parameter placement Can be used in the same way as the optional placement
% argumants of floating environments
\define@key[myStyle]{floating}{placement}[]{
    \PackageInfo{myStyle}{Setting placement to "#1"}
}

% Setting default values.
\savekeys[myStyle]{floating}{caption,label,placement}
\presetkeys[myStyle]{floating}{caption, label, placement=htbp}{}



\newcommand{\img}[2][]{
     \setkeys*{Gin}{#1}
     \setrmkeys[myStyle]{floating}
     \begin{figure}
         \centering
         \includegraphics{#2}
         \caption{\XKV@myStyle@floating@caption@value}
         \label{fig:\XKV@myStyle@floating@label@value}
     \end{figure}
}
\makeatother



\begin{document}
\lipsum[2]

The picture \ref{fig:APicture} shall be located exactly after this line,
however it goes on the top of the page
\img[
    label = APicture,
    caption = Witwe Bolte,
    placement = h!,
    width = 0.3\textwidth
]{mm-01-01}

\lipsum[3]
\end{document}

Answer 1

对于图你可以使用

\begin{figure}

没有选项，但在此之前设置默认值：

\let\fps@figure\XKV@myStyle@floating@placement@value

一般来说你可以

\def\zz{\begin{figure}[}
\expandafter\zz\XKV@myStyle@floating@placement@value]

Answer 2

没有\XKV@myStyle@floating@placement@value定义你什么时候做

\define@cmdkey[myStyle]{floating}{placement}{}

存储值的宏是\cmdmyStyle@floating@placement。因此，您可能想执行以下操作：

\documentclass{article}
\usepackage{xkeyval}
\usepackage[demo]{graphicx}
\usepackage{lipsum}

\makeatletter
\define@cmdkey[myStyle]{floating}{caption}[]{\PackageInfo{myStyle}{Setting caption to "#1"}}
\define@cmdkey[myStyle]{floating}{label}[]{\PackageInfo{myStyle}{Setting label to "#1"}}
\define@cmdkey[myStyle]{floating}{placement}[]{\PackageInfo{myStyle}{Setting caption to "#1"}}
\newcommand{\img}[2][]{%
  \begingroup % don't clutter the key values for the following \img commands
  \setkeys*{Gin}{#1}%
  \setrmkeys[myStyle]{floating}%
  \begingroup\edef\x{\endgroup\noexpand\begin{figure}[\cmdmyStyle@floating@placement]}\x
    \includegraphics{#2}
    \caption{\cmdmyStyle@floating@caption}
    \label{fig:\cmdmyStyle@floating@label}
  \end{figure}
  \endgroup
}
% Setting default values.
\savekeys[myStyle]{floating}{caption,label,placement}
\presetkeys[myStyle]{floating}{caption, label, placement=htbp}{}
\makeatother

\begin{document}
First the references: \ref{fig:TheLabel1} and \ref{fig:TheLabel2}

\lipsum[1]

\img[
  caption = A picture,
  label = TheLabel1,
  placement = h!,
  width=\textwidth,
]{mm-01-01}

\lipsum[2-4]

\img[
  caption = A picture,
  label = TheLabel2,
  placement = t,
  width=\textwidth,
]{mm-01-01}

\lipsum[3]

\end{document}