pgfpages 和页面标签发生了什么？

Question

我正在使用 beamer 的一项功能，可以在幻灯片旁边显示注释，但出来的页码太乱，导致无法将特定幻灯片提取到其他文档中\includegraphics[page=n]{presentation.pdf}。

例如，在这个 MWE 中，有两个框架，每个框架包含 1 张幻灯片，然后有一个框架包含 4 张幻灯片。Acrobat 中显示的 PDF 页面标签如下：2、3、3、3、3 和 7。它从第 2 页开始，而不是第 1 页，然后有 4 个第 3 页，但它们甚至不属于同一框架！

\documentclass{beamer}
\usepackage{pgfpages}

\setbeameroption{show notes on second screen=left}
\setbeamertemplate{note page}{frame \insertframenumber \\ \insertnote}
\def\pg#1{pgfpages says this is page #1 but it is really page \arabic{page}}

\begin{document}

\setcounter{page}{0}

\frame{hi \note{\pg{2}}}

\frame{there \note{\pg{3}}}

\frame{how \pause are \pause you \pause today
\note<1-3>{\pg{3}}
\note<4>{\pg{7}}}

\end{document}

输出内容如下：

我知道手册上说“pgfpages 会在 .aux 文件中产生错误的页码”，并给出了手动解决方法。但计数器page仍然有效，那么难道不应该有某种方法将其传递给 PDF 吗？我想修复这个问题，但不知道从哪里开始。具体来说，当手册上说“TeX 仅在物理页面被发送出去时才在编写 .aux 文件时实例化页码”时，它到底在说什么？它的源代码在哪里？

Answer 1

文件中的页面标签.pdf实际上与文件中的页码无关.aux。页面标签也是在发货时设置的，但由包裹设置hyperref。

pgfpages但是，在下一个/下一个逻辑页面完成后，软件包会发出一个物理页面。这对于“两个屏幕，可选第二个”布局是必要的，以便设置第二个屏幕后主屏幕。但是，副作用是，hyperref当（前一个）物理页面交付时，页面计数器和包的一些页面状态（如页面转换）已经为下一个逻辑页面设置，这会导致错误pdfpagelabels和页面转换发生得太早。

为了解决这个问题，可以在物理页面的第一个逻辑页面即将发货时保存相关的页面状态，并在相应的物理页面发货之前恢复相关的页面状态。

需要注意的是，这一切只有在pgfpages加载时才有效后 hyperref因为hyperref的 shipout hook 只能针对物理页面进行调用。

% Save and restore pdfpage related information for hyperref.
\@ifpackageloaded{hyperref}{

  % Create new counter to save the page counter.
  \newcount\pgfpages@state@c@page

  % The special per-page label 'thispdfpagelabel' is set/cleared
  % globally during hyperref's shipout hook for physical pages.
  % Therefore it must be saved temporarily before physical shipout.
  \def\pgfpages@state@save@temp{%
    \ifHy@pdfpagelabels%
      % \HyPL@thisLabel is only defined if pdfpagelabels are activated.
      \let\pgfpages@state@thisLabel@temp\HyPL@thisLabel%
    \fi%
  }

  % Save all relevant page states if the first logical page is shipped.
  \def\pgfpages@state@save#1{%
    % Probably it should be configurable which logical page is
    % considered, but the first page seems reasonable for now.
    \ifnum#1=\pgf@firstshipout\relax%
      % Save the special per-page label 'thispdfpagelabel', which is
      % temporarily saved before.
      \ifHy@pdfpagelabels%
        \ifx\pgfpages@state@thisLabel@temp\relax%
          \global\let\pgfpages@state@thisLabel\relax%
        \else%
          \xdef\pgfpages@state@thisLabel{\pgfpages@state@thisLabel@temp}%
        \fi%
      \fi%
      % Save the page counter and its formatting.
      \global\pgfpages@state@c@page=\c@page%
      \global\let\pgfpages@state@thepage\thepage%
      % Save the page transition and duration.
      \global\let\pgfpages@state@pdfpagetransition\@pdfpagetransition%
      \global\let\pgfpages@state@pdfpageduration\@pdfpageduration%
    \fi%
  }

  % Restore all relevant page states.
  \def\pgfpages@state@restore{%
    % Restore the special per-page label 'thispdfpagelabel'.
    \ifHy@pdfpagelabels%
      % \HyPL@thisLabel is only defined if pdfpagelabels are activated.
      \let\HyPL@thisLabel\pgfpages@state@thisLabel%
    \fi%
    % Restore the page counter and its formatting.
    \c@page=\pgfpages@state@c@page%
    \let\thepage\pgfpages@state@thepage%
    % Restore the page transition and duration.
    \let\@pdfpagetransition\pgfpages@state@pdfpagetransition%
    \let\@pdfpageduration\pgfpages@state@pdfpageduration%
  }

}{
  % Do nothing if hyperref is not loaded.
  \def\pgfpages@state@save@temp{}
  \def\pgfpages@state@save#1{}
  \def\pgfpages@state@restore{}
}


% "Patch" macros of pgfpages.

\def\pgfpages@shipoutshipoutbox{%
  \begingroup
    \let \protect \noexpand
    \@resetactivechars
    \global\let\@@if@newlist\if@newlist
    \global\@newlistfalse
    \@parboxrestore%
    % Restore page states before physical shipout:
    \pgfpages@state@restore%
    \pgfpages@originalshipout%
    \vbox{\hbox{%
      \hskip-1in%
      \vbox to \pgfphysicalheight{%
        \vss\box\pgfpages@shipoutbox%
        \vskip1in%
      }}}%
  \endgroup%
}

\def\pgfpages@interceptshipout{%
  % Temporarily save some page states which are globally set during
  % physical shipout:
  \pgfpages@state@save@temp%
  \ifnum\pgf@shipoutnextto>0\relax
    \def\pgf@next{%
      \expandafter\global\expandafter\setbox\csname pgfpages@box@\the\pgf@shipoutnextto\endcsname=\box\voidb@x%
      \afterassignment\pgfpages@shipouttestnext%
      \pgfpagesshipoutlogicalpage{\the\pgf@shipoutnextto}%
    }%
  \else%
    \ifpgf@holdingphysicalpage% shipout physical page now
      {\pgfshipoutphysicalpage}%
    \fi%    
    \ifnum\pgf@logicalpages=0\relax
      \def\pgf@next{\pgfpages@originalshipout}%
    \else%
      \def\pgf@next{%
        \expandafter\global\expandafter\setbox\csname pgfpages@box@\the\pgf@currentshipout\endcsname=\box\voidb@x%
        \afterassignment\pgfpages@shipouttest%
        \pgfpagesshipoutlogicalpage{\the\pgf@currentshipout}%
      }%
    \fi%
  \fi%
  \pgf@next%  
}

\renewcommand\pgfpagesshipoutlogicalpage[1]{%
  \global\pgfphysicalpageemptyfalse%
  % Save page states before logical shipout:
  \pgfpages@state@save{#1}%
  \expandafter\global\expandafter\setbox\csname pgfpages@box@#1\endcsname=}