修复 pgfonlayer 的节点定位以防止 gif 抖动

Question

我想使用 tikz 创建 gif。但是，使用pgfonlayer创建多个页面会导致节点在它们之间添加边时发生移动。这会使 gif 非常不稳定。

有没有办法“锁定”这 9 个节点，以便这些节点之间的箭头能够顺利显示在 gif 中？

这是正在创建的 2 个页面的工作示例，但它们未正确对齐。

\documentclass[hyperref={pdfpagelabels=false}]{beamer}
\usepackage{lmodern}

\usepackage{verbatim}
\usepackage{tikz}
\usetikzlibrary{arrows,shapes}

\tikzstyle{box}=[rectangle, draw, thick, minimum size=6mm]
\tikzstyle{up_arrow}=[->, shorten >= 1pt, >=stealth',semithick,bend left]
\tikzstyle{down_arrow}=[->, shorten >= 1pt, >=stealth',semithick,bend right]

\begin{document}
\pgfdeclarelayer{background}
\pgfsetlayers{background,main}

\begin{frame}
    \begin{figure}
        \begin{tikzpicture}[bend angle=45][overlay]
            \node[box] [label=below:{0}] (a0) {a};
            \node[box] [label=below:{1}] (a1) [right of=a0] {b};
            \node[box] [label=below:{2}] (a2) [right of=a1] {c};
            \node[box] [label=below:{3}] (a3) [right of=a2] {a};
            \node[box] [label=below:{4}] (a4) [right of=a3] {d};
            \node[box] [label=below:{5}] (a5) [right of=a4] {d};
            \node[box] [label=below:{6}] (a6) [right of=a5] {c};
            \node[box] [label=below:{7}] (a7) [right of=a6] {a};
            \node[box] [label=below:{8}] (a8) [right of=a7] {c};
            \node[box] [label=below:{9}] (a9) [right of=a8] {d};
            
            \begin{pgfonlayer}{background}
                \draw<1-> [down_arrow] [draw=purple] (a6) to (a8);
                \draw<2-> [up_arrow] [draw=blue] (a5) to (a9);
            \end{pgfonlayer}
        \end{tikzpicture}    
    \end{figure}
\end{frame}

\end{document}

Answer 1

您可以定义一个与图片一样大的边界框，并带有两个箭头，在代码中添加类似内容：

\useasboundingbox (-1,-2) rectangle (10,2);

您还可以利用此overlay-beamer-styles功能使图片的某些路径在不同的幻灯片上不可见或可见。

\documentclass[hyperref={pdfpagelabels=false}]{beamer}
\usepackage{tikz}
\usetikzlibrary{overlay-beamer-styles}

\tikzstyle{box}=[rectangle, draw, thick, minimum size=6mm]
\tikzstyle{up_arrow}=[->, shorten >= 1pt, >=stealth, semithick, bend left]
\tikzstyle{down_arrow}=[->, shorten >= 1pt, >=stealth, semithick, bend right]

\begin{document}
\pgfdeclarelayer{background}
\pgfsetlayers{background,main}

\begin{frame}
    \begin{figure}
        \begin{tikzpicture}[bend angle=45]
            \node[box] [label=below:{0}] (a0) {a};
            \node[box] [label=below:{1}] (a1) [right of=a0] {b};
            \node[box] [label=below:{2}] (a2) [right of=a1] {c};
            \node[box] [label=below:{3}] (a3) [right of=a2] {a};
            \node[box] [label=below:{4}] (a4) [right of=a3] {d};
            \node[box] [label=below:{5}] (a5) [right of=a4] {d};
            \node[box] [label=below:{6}] (a6) [right of=a5] {c};
            \node[box] [label=below:{7}] (a7) [right of=a6] {a};
            \node[box] [label=below:{8}] (a8) [right of=a7] {c};
            \node[box] [label=below:{9}] (a9) [right of=a8] {d};
            
            \begin{pgfonlayer}{background}
                \draw[visible on=<1->, down_arrow] [draw=purple] (a6) to (a8);
                \draw[visible on=<2->, up_arrow] [draw=blue] (a5) to (a9);
            \end{pgfonlayer}
        \end{tikzpicture}    
    \end{figure}
\end{frame}

\end{document}

请注意，该arrows库已被弃用，您可能应该使用较新的arrows.meta库。