如何修复投影仪框架中的 tikzpicture 垂直位置？

Question

在下面的 MWE 中，我必须将相同的图形和下面的一些内容放在一个框架中。它可以工作，但是当从第 1 帧切换到第 2 帧时，tikzpicture 元素会发生偏移，从而产生不良的视觉效果。我该如何消除这种偏移？

\documentclass{beamer}
\usepackage{tikz}
\usetikzlibrary{positioning}

\begin{document}

\begin{frame}
  \frametitle{FRAME 1}
  \centering
  \begin{tikzpicture}
    \node[draw=black] (a) {A};
    \node[draw=black, right=of a] (b) {B};
    \draw (a) -- (b);
  \end{tikzpicture}
  \begin{block}{Block on frame 1}
    \begin{itemize}
    \item Itemize 1 on frame 1
    \item Itemize 2 on frame 2
    \end{itemize}
  \end{block}
\end{frame}

\begin{frame}
  \frametitle{FRAME 2}
  \centering
  \begin{tikzpicture}
    \node[draw=black] (a) {A};
    \node[draw=black, right=of a] (b) {B};
    \draw (a) -- (b);
  \end{tikzpicture}
  \begin{block}{Block on frame 1}
    \begin{itemize}
    \item Itemize 1 on frame 2
    \item Itemize 2 on frame 2
    \item Itemize 3 on frame 2
    \end{itemize}
  \end{block}
\end{frame}

\end{document}

Answer 1

两个选项：

1. t作为两个 s 的可选参数使用frame；这样，框架的内容将顶部对齐：

   \documentclass{beamer}
   \usepackage{tikz}
   \usetikzlibrary{positioning}
   
   \begin{document}
   
   \begin{frame}[t]
     \frametitle{FRAME 1}
     \centering
     \begin{tikzpicture}
       \node[draw=black] (a) {A};
       \node[draw=black, right=of a] (b) {B};
       \draw (a) -- (b);
     \end{tikzpicture}
     \begin{block}{Block on frame 1}
       \begin{itemize}
       \item Itemize 1 on frame 1
       \item Itemize 2 on frame 1
       \end{itemize}
     \end{block}
   \end{frame}
   
   \begin{frame}[t]
     \frametitle{FRAME 2}
     \centering
     \begin{tikzpicture}
       \node[draw=black] (a) {A};
       \node[draw=black, right=of a] (b) {B};
       \draw (a) -- (b);
     \end{tikzpicture}
     \begin{block}{Block on frame 2}
       \begin{itemize}
       \item Itemize 1 on frame 2
       \item Itemize 2 on frame 2
       \item Itemize 3 on frame 2
       \end{itemize}
     \end{block}
     \begin{tikzpicture}
       \node[draw=cyan,fill=orange!30] (c) {C};
       \node[draw=cyan,fill=orange!30,below=of c] (d) {D};
       \draw (c) -- (d);
     \end{tikzpicture}
   \end{frame}
   
   \end{document}
   

   

2. 使用overlayarea环境（根据需要调整环境的高度）。这允许您在第二帧的末尾拥有其他类型的对象，并且仍将保留常见对象的垂直位置：

   \documentclass{beamer}
   \usepackage{tikz}
   \usetikzlibrary{positioning}
   
   \begin{document}
   
   \begin{frame}
     \frametitle{FRAME 1}
   \begin{overlayarea}{\textwidth}{.6\textheight}
     \centering
     \begin{tikzpicture}
       \node[draw=black] (a) {A};
       \node[draw=black, right=of a] (b) {B};
       \draw (a) -- (b);
     \end{tikzpicture}
     \begin{block}{Block on frame 1}
       \begin{itemize}
       \item Itemize 1 on frame 1
       \item Itemize 2 on frame 1
       \end{itemize}
     \end{block}
   \end{overlayarea}
   \end{frame}
   
   \begin{frame}
     \frametitle{FRAME 2}
   \begin{overlayarea}{\textwidth}{.6\textheight}
     \centering
     \begin{tikzpicture}
       \node[draw=black] (a) {A};
       \node[draw=black, right=of a] (b) {B};
       \draw (a) -- (b);
     \end{tikzpicture}
     \begin{block}{Block on frame 2}
       \begin{itemize}
       \item Itemize 1 on frame 2
       \item Itemize 2 on frame 2
       \item Itemize 3 on frame 2
       \end{itemize}
     \end{block}
   \end{overlayarea}
   \end{frame}
   
   \end{document}
   

   结果动画：

   

   第二帧中还有一些物体：

   \documentclass{beamer}
   \usepackage{tikz}
   \usetikzlibrary{positioning}
   
   \begin{document}
   
   \begin{frame}
     \frametitle{FRAME 1}
   \begin{overlayarea}{\textwidth}{.6\textheight}
     \centering
     \begin{tikzpicture}
       \node[draw=black] (a) {A};
       \node[draw=black, right=of a] (b) {B};
       \draw (a) -- (b);
     \end{tikzpicture}
     \begin{block}{Block on frame 1}
       \begin{itemize}
       \item Itemize 1 on frame 1
       \item Itemize 2 on frame 1
       \end{itemize}
     \end{block}
   \end{overlayarea}
   \end{frame}
   
   \begin{frame}
     \frametitle{FRAME 2}
   \begin{overlayarea}{\textwidth}{.6\textheight}
     \centering
     \begin{tikzpicture}
       \node[draw=black] (a) {A};
       \node[draw=black, right=of a] (b) {B};
       \draw (a) -- (b);
     \end{tikzpicture}
     \begin{block}{Block on frame 2}
       \begin{itemize}
       \item Itemize 1 on frame 2
       \item Itemize 2 on frame 2
       \item Itemize 3 on frame 2
       \end{itemize}
     \end{block}
     \begin{tikzpicture}
       \node[draw=cyan,fill=orange!30] (c) {C};
       \node[draw=cyan,fill=orange!30,below=of c] (d) {D};
       \draw (c) -- (d);
     \end{tikzpicture}
   \end{overlayarea}
   \end{frame}
   
   \end{document}
   

   结果：

   

Answer 2

问题是每个框架都是垂直居中的。修复该问题的一种方法是使用\pause：

\documentclass{beamer}
\usepackage{tikz}
\usetikzlibrary{positioning}

\begin{document}

\begin{frame}
  \frametitle{FRAME 1}
  \centering
  \begin{tikzpicture}
    \node[draw=black] (a) {A};
    \node[draw=black, right=of a] (b) {B};
    \draw (a) -- (b);
  \end{tikzpicture}
  \begin{block}{Block on frame 1}
    \begin{itemize}
    \item Itemize 1 on frame 1
    \item Itemize 2 on frame 2
  \pause
    \item Itemize 3 on frame 2
    \end{itemize}
  \end{block}
\end{frame}

\end{document}

另一种方法是添加精确的空间量来弥补高度差异。唉，beamer这并不容易。坦率地说，捏造比计算更容易（大约1.22\baselineskip）。

\documentclass{beamer}
\usepackage{tikz}
\usetikzlibrary{positioning}

\newsavebox{\tempboxa}
\newsavebox{\tempboxb}

\begin{document}

\makeatletter
\savebox{\tempboxa}{\begin{minipage}{\textwidth}%
\let\beamer@cramped=\medskip
  \begin{itemize}
    \item Itemize 1 on frame 1
    \item Itemize 2 on frame 2
  \end{itemize}%
\end{minipage}}

\savebox{\tempboxb}{\begin{minipage}{\textwidth}%
\let\beamer@cramped=\medskip
  \begin{itemize}
    \item Itemize 1 on frame 1
    \item Itemize 2 on frame 2
    \item Itemize 3 on frame 2
  \end{itemize}%
\end{minipage}}
\makeatother

\begin{frame}
  \frametitle{FRAME 1}
  \centering
  \begin{tikzpicture}
    \node[draw=black] (a) {A};
    \node[draw=black, right=of a] (b) {B};
    \draw (a) -- (b);
  \end{tikzpicture}
  \begin{block}{Block on frame 1}

    \usebox{\tempboxa}

    \vspace{\dimexpr \ht\tempboxb+\dp\tempboxb-\ht\tempboxa-\dp\tempboxa}
  \end{block}
\end{frame}

\begin{frame}
  \frametitle{FRAME 2}
  \centering
  \begin{tikzpicture}
    \node[draw=black] (a) {A};
    \node[draw=black, right=of a] (b) {B};
    \draw (a) -- (b);
  \end{tikzpicture}
  \begin{block}{Block on frame 2}

    \usebox{\tempboxb}
  \end{block}
\end{frame}

\end{document}