Beamer 突出显示图像的某些部分并隐藏其余部分

Question 1

编辑
~~使用该overlay-beamer-styles库可以非常优雅地完成此操作。~~ 显然不需要该库，因为 Tikz 宏可以使用!overlay-beamer-styles的覆盖语法。beamer

我以相同的方式包含图像，但将节点命名为image。此外，节点放在哪里并不重要。

\begin{tikzpicture}
    \node[anchor = south west, inner sep = 0] (image) {\includegraphics[width = 0.8\paperwidth, height = 10cm, keepaspectratio] {Effile.jpeg}};

然后我可以定义一个范围，其位于(0,0)左下角image、(1,0)右下角、(0,1)左上角和(1,1)右上角。

    \begin{scope}[shift={(image.south west)},x={(image.south east)},y={(image.north west)}]

现在绘制与图像一起缩放的网格变得非常简单。这样可以轻松识别下一步所需路径的位置。

        % Draw a overlaying grid to easily see where the rectangles must be, this can be commented out in the final version
        \draw foreach \xy in {0,0.1,...,1.001}{
            (\xy,0) -- node[pos=0,below]{\pgfmathprintnumber{\xy}} (\xy,1)
            (0,\xy) -- node[pos=0,left]{\pgfmathprintnumber{\xy}} (1,\xy)};

确定了我想要突出显示的片段的路径后，我可以将它们添加到我的\foreach循环中，该循环会在图像顶部绘制一个大的白色矩形，排除我指定的路径，并在突出显示的片段周围绘制一个额外的红色矩形。此外，该overlay-beamer-styles库还提供了visible on={<>}密钥，可与中的计数器一起使用\foreach。

        \foreach[count=\i] \mypath in {
            {(0.1,0.55) rectangle (0.25,0.65)},
            {(0.45,0.85) rectangle (0.6,0.95)},
            {(0.5,0.5) circle (1cm)},
            {(0.75,0.3) rectangle (0.85,0.35) (0.25,0.75) circle (1.5cm)}
        }{
            \filldraw<\i>[white,opacity=0.75,even odd rule] (0,0) rectangle (1,1) \mypath;
            \draw<\i>[red,ultra thick] \mypath;
        }

最后关闭scope和tikzpicture。

    \end{scope}
\end{tikzpicture}

其结果是：

其中网格仍然可见，并且白色矩形是“透明的”，但对于最终版本，可以将其设为不透明，并且可以隐藏网格。

总 MWE（另请注意，我绘制了网格在上面图像和白色矩形，因为否则它不会很有帮助）：

\documentclass{beamer}
\usepackage[T1]{fontenc}
\usepackage{tikz}

\begin{document}
    \begin{frame}
        \begin{tikzpicture}
            \node[anchor = south west, inner sep = 0] (image) {\includegraphics[width = 0.8\paperwidth, height = 10cm, keepaspectratio] {Effile.jpeg}};

            \begin{scope}[shift={(image.south west)},x={(image.south east)},y={(image.north west)}]

                \foreach[count=\i] \mypath in {
                    {(0.1,0.55) rectangle (0.25,0.65)},
                    {(0.45,0.85) rectangle (0.6,0.95)},
                    {(0.5,0.5) circle (1cm)},
                    {(0.75,0.3) rectangle (0.85,0.35) (0.25,0.75) circle (1.5cm)}
                }{
                    \filldraw<\i>[white,even odd rule] (0,0) rectangle (1,1) \mypath;
                    \draw<\i>[red,ultra thick] \mypath;
                }

%                 Draw a overlaying grid to easily see where the rectangles must be, this can be commented out in the final version
%                \draw foreach \xy in {0,0.1,...,1.001}{
%                    (\xy,0) -- node[pos=0,below]{\pgfmathprintnumber{\xy}} (\xy,1)
%                    (0,\xy) -- node[pos=0,left]{\pgfmathprintnumber{\xy}} (1,\xy)};
            \end{scope}

        \end{tikzpicture}
    \end{frame}
\end{document}

编辑2
由于@marmot 在他的回答中展示了一个奇特的例子，我必须自己添加一些奇特的东西:)

可以通过以下方式实现：

\documentclass{beamer}
\usepackage[T1]{fontenc}
\usepackage{tikz}

\begin{document}
    \begin{frame}
        \begin{tikzpicture}
            \node[anchor = south west, inner sep = 0] (image) {\includegraphics[width = 0.8\paperwidth, height = 10cm, keepaspectratio] {Effile.jpeg}};

            \begin{scope}[shift={(image.south west)},x={(image.south east)},y={(image.north west)}]
                \clip (0,0) rectangle (1,1);
                \foreach[count=\i] \myDim in {0,5,...,106}{
                    \begin{scope}[shift={(0.5,0.5)}]
                        \filldraw<\i>[white,opacity=1,even odd rule,] (-0.5,-0.5) rectangle (0.5,0.5) (0,1.38*\myDim mm)
                            -- ++(288:\myDim mm) -- ++(  0:\myDim mm)
                            -- ++(216:\myDim mm) -- ++(288:\myDim mm)
                            -- ++(144:\myDim mm) -- ++(216:\myDim mm)
                            -- ++( 72:\myDim mm) -- ++(144:\myDim mm)
                            -- ++(  0:\myDim mm) -- cycle;
                        \draw<\i>[red,ultra thick] (0,1.38*\myDim mm)
                            -- ++(288:\myDim mm) -- ++(  0:\myDim mm)
                            -- ++(216:\myDim mm) -- ++(288:\myDim mm)
                            -- ++(144:\myDim mm) -- ++(216:\myDim mm)
                            -- ++( 72:\myDim mm) -- ++(144:\myDim mm)
                            -- ++(  0:\myDim mm) -- cycle;
                    \end{scope}
                }
            \end{scope}

        \end{tikzpicture}
    \end{frame}
\end{document}

编辑3
这（可能_{^（也许）}）将是最后一个：

完成：

\documentclass{beamer}
\usepackage[T1]{fontenc}
\usepackage{tikz}

\usetikzlibrary{shapes}

\begin{document}
    \begin{frame}
        \begin{tikzpicture}
            \node[anchor = south west, inner sep = 0,outer sep=0.5\pgflinewidth] (image) {\includegraphics[width = 0.8\paperwidth, height = 10cm, keepaspectratio] {Effile.jpeg}};

            \clip (image.south west) rectangle (image.north east);

            \foreach[count=\k] \myDim in {0,0.2,...,3.4}{
                \ifnum\k>1
                    \def\mypath{
                        [scale={\myDim^2}] (image.center)
                        foreach \myPhi [count=\i,evaluate=\i as \j using {0.5*mod(\i,2)+0.5}] in {0,36,...,359}{
                            \ifnum\i=1
                                   +({90+50*sqrt(\k)+\myPhi}:\j)
                                \else
                                -- +({90+50*sqrt(\k)+\myPhi}:\j)
                            \fi
                        } -- cycle
                    }
                \else
                    \def\mypath{}
                \fi

                \filldraw<\k>[white]
                    (image.south west) rectangle (image.north east) \mypath;
                \draw<\k>[red,ultra thick] \mypath;
            }

        \end{tikzpicture}
    \end{frame}
\end{document}

编辑4
这确实是最后一个：

使用命令完成\clip（偷偷从@marmot 的答案中偷来的）。我还定义了一个use node cs以节点名称为参数的样式，这样更容易在相对坐标系中绘制：

\documentclass{beamer}
\usepackage[T1]{fontenc}
\usepackage{tikz}

\usetikzlibrary{calc}

\tikzset{
    use node cs/.style={shift={(#1.south west)},x={(#1.south east)},y={(#1.north west)}}
}

\begin{document}
    \begin{frame}
        \begin{tikzpicture}
            \node[anchor = south west, inner sep = 0,opacity=0] (image) {\includegraphics[width = 0.8\paperwidth, height = 10cm, keepaspectratio] {Effile.jpeg}};

            \clip (image.south west) rectangle (image.north east);

            \foreach \myDim [count=\i] in{0,...,30}{
                \clip<\i>[use node cs=image] let 
                    \n1={max(\myDim,0)},
                    \n2={max(\myDim - 1,0)},
                    \n3={max(\myDim - 2,0)},
                    \n4={max(\myDim - 3,0)},
                    \n5={max(\myDim - 4,0)}
                in 
                    (0.1,0.2) circle (\n1 mm)
                    (0.6,0.4) circle (\n2 mm)
                    (0.8,0.2) circle (\n5 mm)
                    (0.5,0.3) circle (\n1 mm)
                    (0.1,0.8) circle (\n5 mm)
                    (0.4,0.9) circle (\n3 mm)
                    (0.7,0.7) circle (\n1 mm)
                    (0.2,0.5) circle (\n3 mm)
                    (0.9,0.6) circle (\n2 mm)
                    (0.9,0.8) circle (\n1 mm);
            }
            \node[anchor = south west, inner sep = 0] {\includegraphics[width = 0.8\paperwidth, height = 10cm, keepaspectratio] {Effile.jpeg}};

        \end{tikzpicture}
    \end{frame}
\end{document}

Answer