Re: [O] Beamer export with \only overlays - how?

[James Harkins]

Suvayu Ali <fatkasuvayu+linux <at> gmail.com> writes:

> On Tue, Oct 08, 2013 at 11:41:36PM +0800, James Harkins wrote:
> > Question: How does one use Beamer's \only command with blocks?
(Successfully, with org-mode's beamer
> export, I mean.)
> > 
> > I found in the manual that you can give an overlay specification using
> > the BEAMER_ACT property... ok... but that's not the same as \only
> > because, when a latex chunk is marked \only<1>, it takes *no space* on
> > <2->. Using <1> and <2> causes the <2> to appear lower than the
> > <1>. That's not what I want.
> > 
> 
> Did you try this:
> 
> <http://orgmode.org/worg/exporters/beamer/ox-beamer.html#environments-overlay>

My example file uses BEAMER_ACT, so yes, I did try that. Here's what happens
if I try it with \only<1>.

#+LANGUAGE:  en
#+OPTIONS:   H:2 num:t toc:t \n:nil @:t ::t |:t ^:t -:t f:t *:t <:t ':t
#+OPTIONS:   TeX:t LaTeX:t skip:nil d:nil todo:t pri:nil tags:not-in-toc
#+EXPORT_SELECT_TAGS: export
#+EXPORT_EXCLUDE_TAGS: noexport

#+startup: beamer
#+LaTeX_CLASS: beamer
#+LaTeX_CLASS_OPTIONS: [presentation]
#+BEAMER_THEME: default
#+COLUMNS: %45ITEM %10BEAMER_env(Env) %10BEAMER_act(Act) %4BEAMER_col(Col)
%8BEAMER_opt(Opt)
#+PROPERTY: BEAMER_col_ALL 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0.0 :ETC

* Section
** Frame (beamer_act, not quite right)
*** The problem on this frame
    I want Block 1 and Block 2 to occupy the same space on successive slides.
*** Block 1                                                         :B_block:
    :PROPERTIES:
    :BEAMER_env: block
    :BEAMER_ACT: \only<1>
    :END:
*** Block 2                                                         :B_block:
    :PROPERTIES:
    :BEAMER_env: block
    :BEAMER_ACT: \only<2>
    :END:

-->

\begin{block}<\only<1>>{Block 1}
\end{block}

Where the correct syntax would be:

\only<1>{
\begin{block}{Block 1}
\end{block}
}

So in short, no, that doesn't help.

I'm getting the uncomfortable feeling that this is a use case that org just
doesn't support as yet.

Actually, reading further in the beamer user guide, I noticed last night
that what I really want is \overlayarea, e.g.:

\begin{overlayarea}{\textwidth}{3cm}
\only<1>{Some text for the first slide.\\Possibly several lines long.}
\only<2>{Replacement on the second slide.}
\end{overlayarea}

Unfortunately \overlayarea is not supported as a BEAMER_env:

*** dummy                                                     :B_overlayarea:
    :PROPERTIES:
    :BEAMER_env: overlayarea
    :BEAMER_envargs: {\textwidth}{3cm}
    :END:

There's no \begin{overlayarea} or \end{overlayarea} anywhere in the exported
code.

Oh, forgot: org-version says Org-mode version 8.2 (release_8.2-1-g025bb7 @
/home/dlm/share/org-mode.git/lisp/).

hjh