在每个图形上打印“比例因子”作为水印

Question

来自上一个问题（\includegraphics：获取图形的“比例”值，其大小由“宽度”表示) 我学习了如何获取scale factor通过\includegraphics命令插入的图形的。

现在我想将文档中每个图形上的缩放值打印为水印。我从这里开始：

\documentclass{article}
\pdfoutput=1
\usepackage{graphicx}
\usepackage{color}

\makeatletter
\let\ORG@Gscale@box\Gscale@box
\long\def\Gscale@box#1{%
  \xdef\thelastscalefactor{#1}%
  \ORG@Gscale@box{#1}}
\makeatother

\begin{document}

\includegraphics[width=0.4\textwidth]{example-image}
\colorbox{red}{\the\thelastscalefactor}

\end{document}

最好的解决方案是重新定义\includegraphics命令来执行此操作，但也可以\myincludegraphics像我的另一个问题中那样定义命令https://tex.stackexchange.com/a/455293/33634。

最后，我还遇到了一个与字符串有关的问题\the\thelastscalefactor：

! You can't use `the character 0' after \the.
\thelastscalefactor ->0
                       .3437

Answer 1

以下是一种解决方案：

\documentclass{article}
\usepackage{graphicx}
\usepackage{xcolor}

\makeatletter
\let\ORG@Gscale@box\Gscale@box
\long\def\Gscale@box#1{%
  \xdef\thelastscalefactor{#1}%
  \ORG@Gscale@box{#1}}
\makeatother

\newsavebox{\mybox}

% Make the top left corner of the annotation box start at 10% (1-0.9)
% from the left edge of the image and at 10% (0.1) from the top edge (this
% is why it lies exactly on the diagonal in the screenshot).
\newcommand*{\putimagescale}[1]{%
  \sbox{\mybox}{#1}%
  \usebox{\mybox}%
  \hbox to 0pt{\kern-0.9\wd\mybox
               \vbox to \ht\mybox{%
                 \kern0.1\ht\mybox
                 \hbox{\colorbox{red}{\thelastscalefactor}}%
                 \vss
               }%
               \hss
  }}

% Alternative method: the placement is done differently. In particular, the
% vertical offset is counted from the baseline of the image to the baseline of
% the annotation box.
% \newcommand*{\putimagescale}[1]{%
%   \sbox{\mybox}{#1}%
%   \usebox{\mybox}%
%   \makebox[0pt][r]{%
%     \raisebox{0.8\ht\mybox}[0pt][0pt]{%
%       \rlap{\colorbox{red}{\thelastscalefactor}}%
%     }%
%     \hspace*{0.9\wd\mybox}%
%   }%
% }

% You can uncomment the following if you want \includegraphics to be redefined
% so as to always print the image scale (obviating the need to manually call
% \putimagescale).
%
% \let\includegraphicsORI\includegraphics
% \renewcommand*{\includegraphics}[2][]{%
%   \putimagescale{\includegraphicsORI[#1]{#2}}}

\begin{document}

\putimagescale{%
  \includegraphics[width=0.4\textwidth]{example-image}}

\end{document}

替代方法给出（垂直放置不一样）：

Answer 2

TikZ 可能有点过头了，但至少我知道怎么做......

\documentclass{article}
\pdfoutput=1
\usepackage{tikz} % loads graphicx and xcolor

\makeatletter
\let\ORG@Gscale@box\Gscale@box
\long\def\Gscale@box#1{%
  \xdef\thelastscalefactor{#1}%
  \ORG@Gscale@box{#1}}
\makeatother

\newcommand\myincludegraphics[2][]{%
\begin{tikzpicture}
\node [inner sep=0] (img) {\includegraphics[#1]{#2}};
\node [below right,fill=red,draw=black] at (img.north west) {\thelastscalefactor}; % no \the needed
\end{tikzpicture}%
}

\begin{document}

\myincludegraphics[scale=1]{example-image}

\myincludegraphics[width=0.6\textwidth]{example-image}

\myincludegraphics[scale=0.5]{example-image}

\end{document}