Document Classes ⇒ Beamer: Block width?

[pebo]

Hello,
what's the best way to draw a block with some contents, as with the block environment, that does not span over the whole slide's width?
Currently I use a single column with a specified width, but I find it a little long:

Code: Select all

\begin{columns}
\column{7em}
\begin{block}{Title}Text
\end{block}
\end{columns}

Any hint is appreciated

[Stefan Kottwitz]

Hi Pebo,

you could define your own block environment with an optional parameter for its width. Have a look at this example:

Code: Select all

\documentclass{beamer}
\usetheme{Warsaw}
\usepackage[english]{babel}
\title{Variable block demo}
\author{Stefan Kottwitz}

\newenvironment<>{varblock}[2][\textwidth]{%
  \setlength{\textwidth}{#1}
  \begin{actionenv}#3%
    \def\insertblocktitle{#2}%
    \par%
    \usebeamertemplate{block begin}}
  {\par%
    \usebeamertemplate{block end}%
  \end{actionenv}}

\begin{document}

\begin{frame}
\begin{block}{Standard}
  Normal block
\end{block}
\begin{varblock}[4cm]{New block}
  Variable width, here 4cm
\end{varblock}
\begin{varblock}{New block}
  If no width was given, \textbackslash textwidth will be used
\end{varblock}
\end{frame}

\end{document}

Stefan

[mathfeel]

Hi Pebo,

you could define your own block environment with an optional parameter for its width. Have a look at this example:

Code: Select all

\documentclass{beamer}
\usetheme{Warsaw}
\usepackage[english]{babel}
\title{Variable block demo}
\author{Stefan Kottwitz}

\newenvironment<>{varblock}[2][\textwidth]{%
  \setlength{\textwidth}{#1}
  \begin{actionenv}#3%
    \def\insertblocktitle{#2}%
    \par%
    \usebeamertemplate{block begin}}
  {\par%
    \usebeamertemplate{block end}%
  \end{actionenv}}

\begin{document}

\begin{frame}
\begin{block}{Standard}
  Normal block
\end{block}
\begin{varblock}[4cm]{New block}
  Variable width, here 4cm
\end{varblock}
\begin{varblock}{New block}
  If no width was given, \textbackslash textwidth will be used
\end{varblock}
\end{frame}

\end{document}

Stefan

Been looking for this. Thanks. One thing: the resized block is not centered (The box is left-aligned). How do I center the box?

[Stefan Kottwitz]

You could center the box by using a center environment and a minipage environment, if needed:

Code: Select all

\begin{center}
  \begin{minipage}{4cm}
    \begin{varblock}[4cm]{title}
      text
    \end{varblock}
  \end{minipage}
\end{center}

Stefan

[mathfeel]

Yes, but this would defeat the purpose of reusing code. Suppose I want some new environment called "cvarbox", I cannot just stick the \begin{center} and \begin{minipage} into the \newenvironment<>, can I?

I am not familiar with TeX, so I am not sure how to do this. Thanks.

[EDIT]:GOT IT. Simply inserting center/minipage in the newenvironment definition worked.

[fabriciomarques1]

Hi,
I achieve what you were trying to do by changing the Stefan's code as:

Code: Select all

    
\newenvironment<>{varblock}[2][\textwidth]{
    \begin{center}
      \begin{minipage}{#1}
        \setlength{\textwidth}{#1}
          \begin{actionenv}#3
            \def\insertblocktitle{#2}
            \par
            \usebeamertemplate{block begin}}
  {\par
      \usebeamertemplate{block end}
    \end{actionenv}
  \end{minipage}
\end{center}}

[guest75]

Hi Stefan,

can you please explain me the environment

Code: Select all

\begin{actionenv}#3%
\end{actionenv}

you used in your code? I neither understand the explanation in the TikZ documentation nor do I see any difference if I use your code without those two lines.

Additionally, is it possible to limit the width of the block automatically to the size of (a longer) text (with some \\ in it)?

Tom

[Stefan Kottwitz]

Hi Tom,

it's described in the beamer manual, if you follow the link it's in 9.6.3 Action Specifications. And full text search gives examples of use.

Regarding automatically choosen width, perhaps it's possible using the varwidth package.

Stefan

[guest75]

Hi Stefan,

thanks, I think I understood \newenvironement<> a litte bit better.

There are still two thinks I'm not sure about

Why do you have to use \def\insertblocktitle{#2}? I read that one shouldn't use \def but \renewcommand{\insertblocktitle}{#2}.

And I'm not sure why I have to use the \par commands for a new paragraph. The output is the same without them.

Regarding automatically choosen width, perhaps it's possible using the varwidth package.

Ok, I'll try this.

Tom

[Stefan Kottwitz]

Hi Tom,

I took it from the original block environment code which is:

Code: Select all

\newenvironment<>{block}[1]{%
  \begin{actionenv}#2%
    \def\insertblocktitle{#1}%
    \par%
    \usebeamertemplate{block begin}}
  {\par%
    \usebeamertemplate{block end}%
  \end{actionenv}}

Based on this I created the modified variable environment above. So the only reason for me was to use the same code for consistency.

Yes, LaTeX users should use \renewcommand which is higher level and safer. Package programmers use \def because it's faster. For user code, safety is more important than speed.

Stefan