設計自訂標題頁範本時如何偵測日期欄位是否為空？

Question

我正在嘗試建立自訂標題頁，但無法編寫巨集來檢測日期欄位是否為空。如果是，block則應簡單地繞過日期條目。

上圖看起來很奇怪，因為顯示了日期區塊標題，但實際日期為空。當然，我可以手動刪除這種情況下的日期區塊，但我仍然希望自動完成此操作。我還想知道如何確定某個欄位是否為空。

\documentclass[aspectratio=169, xcolor={x11names}]{beamer}


\usecolortheme{rose}

    \setbeamercolor{itemize item}{fg=black}

\useoutertheme[]{tree}

\useinnertheme{inmargin}

    \setbeamersize{text margin left=2mm, text margin right=2mm}

    \newlength{\sidebarWidth}
    \setlength{\sidebarWidth}{0.2\paperwidth}

    \setbeamersize{sidebar width left=\sidebarWidth, sidebar width right=0cm}

\usefonttheme{structurebold}


\title{The Main Title of The Presentation}
\subtitle{Short Title Goes here}
\author{Al-Motasem Aldaoudeyeh}
\institute{North Dakota State University}
\date{}

\setbeamertemplate{headline}{}

\setbeamertemplate{date}{nothing}

\setbeamercolor{block title}{fg=blue}
\setbeamerfont{title page}{shape=\bfseries}


% Custome title page
\setbeamertemplate{title page}{
    \vspace*{\stretch{3}}
    \begin{block}{}
        \usebeamercolor[fg]{title page}\usebeamerfont{block title}\usebeamertemplate{block title}
        \inserttitle
    \end{block}
    \begin{block}{}
        \usebeamercolor[fg]{title page}\usebeamerfont{block title}\usebeamertemplate{block title}
        \large \insertsubtitle
    \end{block}
    \vspace{\stretch{2}}
    \begin{block}{Author}
        \insertauthor
    \end{block}
    \begin{block}{Institute}
        \insertinstitute
    \end{block}
    \begin{block}{Date}
        \insertdate
    \end{block}
    \vspace{\stretch{5}}
                            }

\begin{document}

\begin{frame}
    \titlepage
\end{frame}

\end{document}

Answer 1

如果日期確實為空（例如，如果您的文件包含\date{}），那麼您可以使用以下命令對此進行測試

\ifx\insertdate\empty%
\else%
   \begin{block}{Date}
       \insertdate
   \end{block}   
\fi

請注意，如果您的文件不包含任何\date命令，則預設會顯示目前日期。

\documentclass[aspectratio=169, xcolor={x11names}]{beamer}

\usecolortheme{rose}
\setbeamercolor{itemize item}{fg=black}
\useoutertheme[]{tree}
\useinnertheme{inmargin}

\setbeamersize{text margin left=2mm, text margin right=2mm}
\newlength{\sidebarWidth}
\setlength{\sidebarWidth}{0.2\paperwidth}

\setbeamersize{sidebar width left=\sidebarWidth, sidebar width right=0cm}

\usefonttheme{structurebold}


\title{The Main Title of The Presentation}
\subtitle{Short Title Goes here}
\author{Al-Motasem Aldaoudeyeh}
\institute{North Dakota State University}
\date{}

\setbeamertemplate{headline}{}

\setbeamertemplate{date}{nothing}

\setbeamercolor{block title}{fg=blue}
\setbeamerfont{title page}{shape=\bfseries}


% Custome title page
\setbeamertemplate{title page}{
    \vspace*{\stretch{3}}
    \begin{block}{}
        \usebeamercolor[fg]{title page}\usebeamerfont{block title}\usebeamertemplate{block title}
        \inserttitle
    \end{block}
    \begin{block}{}
        \usebeamercolor[fg]{title page}\usebeamerfont{block title}\usebeamertemplate{block title}
        \large \insertsubtitle
    \end{block}
    \vspace{\stretch{2}}
    \begin{block}{Author}
        \insertauthor
    \end{block}
    \begin{block}{Institute}
        \insertinstitute
    \end{block}
    \ifx\insertdate\empty%
    \else%
       \begin{block}{Date}
           \insertdate
       \end{block}   
    \fi
    \vspace{\stretch{5}}
                            }


\begin{document}

\begin{frame}
    \titlepage
\end{frame}

\end{document}

Answer 2

這是一個答案適用於空日期或“白色”日期

\documentclass[aspectratio=169, xcolor={x11names}]{beamer}

% Added code:
\makeatletter
\newcommand{\AddDateBox}{\xdef\mystring{\insertdate}\sbox1{\hbox{\mystring}}\sbox2{\hbox{\space}}\ifdim\wd1=\wd2\relax\else\ifx\insertdate\empty\relax\else\begin{block}{Date}\insertdate\end{block}\fi\fi}
\makeatother


\usecolortheme{rose}

\setbeamercolor{itemize item}{fg=black}

\useoutertheme[]{tree}

\useinnertheme{inmargin}

    \setbeamersize{text margin left=2mm, text margin right=2mm}

    \newlength{\sidebarWidth}
    \setlength{\sidebarWidth}{0.2\paperwidth}

    \setbeamersize{sidebar width left=\sidebarWidth, sidebar width right=0cm}

\usefonttheme{structurebold}


\title{The Main Title of The Presentation}
\subtitle{Short Title Goes here}
\author{Al-Motasem Aldaoudeyeh}
\institute{North Dakota State University}
\date{}

\setbeamertemplate{headline}{}

\setbeamertemplate{date}{nothing}

\setbeamercolor{block title}{fg=blue}
\setbeamerfont{title page}{shape=\bfseries}


% Custome title page
\setbeamertemplate{title page}{
    \vspace*{\stretch{3}}
    \begin{block}{}
        \usebeamercolor[fg]{title page}\usebeamerfont{block title}\usebeamertemplate{block title}
        \inserttitle
    \end{block}
    \begin{block}{}
        \usebeamercolor[fg]{title page}\usebeamerfont{block title}\usebeamertemplate{block title}
        \large \insertsubtitle
    \end{block}
    \vspace{\stretch{2}}
    \begin{block}{Author}
        \insertauthor
    \end{block}
    \begin{block}{Institute}
        \insertinstitute
    \end{block}
    \AddDateBox
    \vspace{\stretch{5}}
                            }

\begin{document}

\begin{frame}
    \titlepage
\end{frame}

\end{document}