我正在创建一个 beamertemplate（实际上是用于 beamerposter），我想增加一个块的半径。根据 beamer 手册 (12.3)，我可以将选项传递[rounded]给一个块或 beamertemplate blocks，以使边框变圆。但圆角看起来真的很小，所以我想尝试一下指定圆角的圆的半径。我该怎么做？
答案1
文档类beamer内部使用\pgfpathqmoveto、\pgfpathqcurveto和\pgfpathlineto来构建圆角框，因此您可以使用原始定义中使用的值（可以在文件中找到beamerbaseboxes.sty）。
在下面的代码中，我展示了一种变化，其中我改变了块上部圆角的值（这些更改必须在 的定义中进行\beamerboxesrounded，它构建了块的上部）；原始定义% original在行尾被注释掉并标有 ；修改后的行紧随其后，并标有% NEW。
要更改块底部的圆角，您必须对\endbeamerboxesrounded（构建块下部）的某些行进行类似的更改；需要进行更改的行以 标记% original:change。
\documentclass{beamer}
\usetheme{Warsaw}
\setbeamertemplate{blocks}[rounded]
\makeatletter
\renewcommand\beamerboxesrounded[2][]{%
\global\let\beamer@firstlineitemizeunskip=\relax%
\vbox\bgroup%
\setkeys{beamerboxes}{upper=block title,lower=block body,width=\textwidth,shadow=false}%
\setkeys{beamerboxes}{#1}%
{%
\usebeamercolor{\bmb@lower}%
\globalcolorstrue%
\colorlet{lower.bg}{bg}%
}%
{%
\usebeamercolor{\bmb@upper}%
\globalcolorstrue%
\colorlet{upper.bg}{bg}%
}%
%
% Typeset head
%
\vskip4bp
\setbox\bmb@box=\hbox{%
\begin{minipage}[b]{\bmb@width}%
\usebeamercolor[fg]{\bmb@upper}%
#2%
\end{minipage}}%
\ifdim\wd\bmb@box=0pt%
\setbox\bmb@box=\hbox{}%
\ht\bmb@box=1.5pt%
\bmb@prevheight=-4.5pt%
\else%
\wd\bmb@box=\bmb@width%
\bmb@temp=\dp\bmb@box%
\ifdim\bmb@temp<1.5pt%
\bmb@temp=1.5pt%
\fi%
\setbox\bmb@box=\hbox{\raise\bmb@temp\hbox{\box\bmb@box}}%
\dp\bmb@box=0pt%
\bmb@prevheight=\ht\bmb@box%
\fi%
\bmb@temp=\bmb@width%
\bmb@dima=\bmb@temp\advance\bmb@dima by2.2bp%
\bmb@dimb=\bmb@temp\advance\bmb@dimb by4bp%
\hbox{%
\begin{pgfpicture}{0bp}{+-\ht\bmb@box}{0bp}{+-\ht\bmb@box}
\ifdim\wd\bmb@box=0pt%
\color{lower.bg}%
\else%
\color{upper.bg}%
\fi%
% \pgfpathqmoveto{-4bp}{-1bp}% original
% \pgfpathqcurveto{-4bp}{1.2bp}{-2.2bp}{3bp}{0bp}{3bp}% original
\pgfpathqmoveto{-4bp}{-6bp}% NEW
\pgfpathqcurveto{-4bp}{-0.8bp}{-1.2bp}{2bp}{5bp}{3bp}% NEW
% \pgfpathlineto{\pgfpoint{\bmb@temp}{3bp}}% original
\pgfpathlineto{\pgfpoint{\bmb@temp-6pt}{3bp}}% NEW
\pgfpathcurveto%
% {\pgfpoint{\bmb@dima}{3bp}}% original
% {\pgfpoint{\bmb@dimb}{1.2bp}}% original
% {\pgfpoint{\bmb@dimb}{-1bp}}% original
{\pgfpoint{\bmb@dima-2bp}{1bp}}% NEW
{\pgfpoint{\bmb@dimb-2bp}{-1.2bp}}% NEW
{\pgfpoint{\bmb@dimb}{-6bp}}% NEW
\bmb@dima=-\ht\bmb@box%
\advance\bmb@dima by-2pt%
\pgfpathlineto{\pgfpoint{\bmb@dimb}{\bmb@dima}}
\pgfpathlineto{\pgfpoint{-4bp}{\bmb@dima}}
\pgfusepath{fill}
\end{pgfpicture}%
\copy\bmb@box%
}%
\nointerlineskip%
\vskip-1pt%
\ifdim\wd\bmb@box=0pt%
\else%
\hbox{%
\begin{pgfpicture}{0pt}{0pt}{\bmb@width}{6pt}
\bmb@dima=\bmb@width%
\advance\bmb@dima by8bp%
\pgfpathrectangle{\pgfpoint{-4bp}{-1bp}}{\pgfpoint{\bmb@dima}{8bp}}
\pgfusepath{clip}
{\pgftransformshift{\pgfpoint{-4bp}{0bp}}\pgftext[left,base]{\pgfuseshading{bmb@transition}}}%
\end{pgfpicture}%
}%
\nointerlineskip%
\vskip-0.5pt%
\fi%
\ifbmb@shadow%
\setbox\bmb@boxshadow=\hbox{\pgfuseshading{bmb@shadow}}%
\setbox\bmb@boxshadowball=\hbox{\pgfuseshading{bmb@shadowball}}%
\setbox\bmb@boxshadowballlarge=\hbox{\pgfuseshading{bmb@shadowballlarge}}%
\fi%
\setbox\bmb@colorbox=\hbox{{\pgfpicturetrue\pgfsetcolor{lower.bg}}}%
\setbox\bmb@box=\hbox\bgroup\begin{minipage}[b]{\bmb@width}%
\vskip2pt%
\usebeamercolor[fg]{\bmb@lower}%
\colorlet{beamerstructure}{upper.bg}%
\colorlet{structure}{upper.bg}%
%\color{.}%
}
\def\endbeamerboxesrounded{%
\end{minipage}\egroup%
\wd\bmb@box=\bmb@width%
\bmb@temp=\dp\bmb@box%
\advance\bmb@temp by.5pt%
\setbox\bmb@box=\hbox{\raise\bmb@temp\hbox{\box\bmb@box}}%
\dp\bmb@box=0pt%
\bmb@temp=\wd\bmb@box%
\bmb@dima=\bmb@temp\advance\bmb@dima by2.2bp%
\bmb@dimb=\bmb@temp\advance\bmb@dimb by4bp%
\hbox{%
\begin{pgfpicture}{0bp}{0bp}{0bp}{0bp}
\ifbmb@shadow%
{\pgftransformshift{\pgfpoint{4bp}{-3bp}}\pgftext{\copy\bmb@boxshadowball}}
\begin{pgfscope}
{%
\advance\bmb@temp by-1bp%
\pgfpathrectangle{\pgfpoint{\bmb@temp}{-7bp}}{\pgfpoint{9bp}{9bp}}%
\pgfusepath{clip}
}%
{\pgftransformshift{\pgfpoint{\bmb@temp}{1bp}}\pgftext{\box\bmb@boxshadowballlarge}}
\end{pgfscope}
\begin{pgfscope}
\advance\bmb@temp by-4bp%
\pgfpathrectangle{\pgfpoint{4bp}{-7bp}}{\pgfpoint{\bmb@temp}{5bp}}
\pgfusepath{clip}
{\pgftransformshift{\pgfpoint{4bp}{-7bp}}\pgftext[left,base]{\copy\bmb@boxshadow}}%
\end{pgfscope}
\begin{pgfscope}
\advance\bmb@temp by 4bp%
\bmb@dima=\ht\bmb@box%
\advance\bmb@dima by\bmb@prevheight%
\advance\bmb@dima by 4bp%
\pgfpathrectangle{\pgfpoint{\bmb@temp}{1bp}}{\pgfpoint{4bp}{\bmb@dima}}
\pgfusepath{clip}
\advance\bmb@dima by-4bp%
{\pgftransformshift{\pgfpoint{\bmb@temp}{\bmb@dima}}\pgftext{\box\bmb@boxshadowball}}
\advance\bmb@dima by-1bp%
\pgfpathrectangle{\pgfpoint{\bmb@temp}{1bp}}{\pgfpoint{4bp}{\bmb@dima}}
\pgfusepath{clip}
\advance\bmb@temp by4bp%
{\pgftransformshift{\pgfpoint{\bmb@temp}{-3bp}}%
\pgftransformrotate{90}%
\pgftext[left,base]{\box\bmb@boxshadow}}%
\end{pgfscope}
\fi%
\unhbox\bmb@colorbox%
\pgfpathqmoveto{-4bp}{1bp}% original:change
\pgfpathqcurveto{-4bp}{-1.2bp}{-2.2bp}{-3bp}{0bp}{-3bp}% original:change
\pgfpathlineto{\pgfpoint{\the\bmb@temp}{-3bp}}% original:change
\pgfpathcurveto%
{\pgfpoint{\the\bmb@dima}{-3bp}}% original:change
{\pgfpoint{\the\bmb@dimb}{-1.2bp}}% original:change
{\pgfpoint{\the\bmb@dimb}{1bp}}% original:change
{
\bmb@dima=\ht\bmb@box%
\pgfpathlineto{\pgfpoint{\bmb@dimb}{\bmb@dima}}
\pgfpathlineto{\pgfpoint{-4bp}{\bmb@dima}}
\pgfusepath{fill}
}
\ifbmb@shadow%
{
\color{black!50!bg}
\pgfsetlinewidth{0pt}
\pgfpathmoveto{\pgfpoint{\bmb@dimb}{-.5bp}}
\bmb@dima=\ht\bmb@box%
\advance\bmb@dima by\bmb@prevheight%
\advance\bmb@dima by 1bp%
\pgfpathlineto{\pgfpoint{\bmb@dimb}{\bmb@dima}}
\pgfusepath{stroke}
\bmb@temp=\bmb@dima
\advance\bmb@dima by 1bp%
\color{black!31!bg}
\pgfpathmoveto{\pgfpoint{\bmb@dimb}{\bmb@temp}}
\pgfpathlineto{\pgfpoint{\bmb@dimb}{\bmb@dima}}
\pgfusepath{stroke}
\advance\bmb@dima by 1bp%
\advance\bmb@temp by 1bp%
\color{black!19!bg}
\pgfpathmoveto{\pgfpoint{\bmb@dimb}{\bmb@temp}}
\pgfpathlineto{\pgfpoint{\bmb@dimb}{\bmb@dima}}
\pgfusepath{stroke}
\advance\bmb@dima by 1bp%
\advance\bmb@temp by 1bp%
\color{black!6!bg}
\pgfpathmoveto{\pgfpoint{\bmb@dimb}{\bmb@temp}}
\pgfpathlineto{\pgfpoint{\bmb@dimb}{\bmb@dima}}
\pgfusepath{stroke}
\advance\bmb@dima by 1.5bp%
\advance\bmb@temp by 1bp%
\color{bg}
\pgfpathmoveto{\pgfpoint{\bmb@dimb}{\bmb@temp}}
\pgfpathlineto{\pgfpoint{\bmb@dimb}{\bmb@dima}}
\pgfusepath{stroke}
}
\fi
\end{pgfpicture}%
\box\bmb@box%
}%
\ifbmb@shadow%
\vskip4bp minus 2bp%
\else%
\vskip2bp%
\fi%
\egroup% of \vbox\bgroup
}
\makeatother
\begin{document}
\begin{frame}
\begin{exampleblock}{test}
test
\end{exampleblock}
\end{frame}
\end{document}
