The errors are my fault with the code. But we should distinguish:
- the numbering problem;
- the
align problem.
For what concern the numbering problem it could be easily solved: at the moment equations are not numbered due to the call
\opaqueblock<#1>[\wd\mybox]{\[\BODY\]}
Of course, replacing \[\BODY\] with
\opaqueblock<#1>[\wd\mybox]{\begin{equation}\BODY\end{equation}}
is of help, but we still missing the fact that we previously measure the width of $\BODY$ without numbers, so the width of the box is wrong. A workaround is:
\NewEnviron{cdyn}[1]{%
\sbox{\mybox}{$\BODY \qquad (1)$}%
\begin{center}
\begin{dynblock}
\opaqueblock<#1>[\wd\mybox]{\begin{equation}\BODY\end{equation}}
\end{dynblock}
\end{center}
}{}%
A complete example:
\documentclass[t]{beamer}
\usepackage{lmodern}
\usetheme{Madrid}
\usepackage[customcolors,shadow,roundedcorners]{dynblocks}
% setting the block body color
\usebeamercolor{block body}
\definecolor{my block body}{named}{bg}
\setbordercolor{my block body}
\setblockcolor{my block body}
% new enviroment always centered
\usepackage{environ}
\newsavebox\mybox
% new environment cdyn: #1 => overlay specification
\NewEnviron{cdyn}[1]{%
\sbox{\mybox}{$\BODY \qquad (1)$}%
\begin{center}
\begin{dynblock}
\opaqueblock<#1>[\wd\mybox]{\begin{equation}\BODY\end{equation}}
\end{dynblock}
\end{center}
}{}%
\begin{document}
\begin{frame}{Test}
\abovedisplayskip=0pt
\begin{cdyn}{1-}
c^2=a^2+b^2
\end{cdyn}
\begin{cdyn}{2-}
x+y=400
\end{cdyn}
\begin{cdyn}{3-}
\sum_{l _1+\dots+ l _p=l}\prod^p_{i=1} \binom{n_i}{l _i}+
\sum_{l _1+\dots+ l _p=l}\prod^p_{i=1} \binom{n_i}{l _i}\label{eq:sum}
\end{cdyn}
\begin{cdyn}{4-}
q_{n+1}=q_n-\Delta_n+\theta_n \qquad \Delta_n=
\begin{cases}
1 \quad q_n>0\\
0 \quad q_n=0
\end{cases}
\end{cdyn}
\only<4->{I'm referring to \eqref{eq:sum}.}
\end{frame}
\end{document}
The result:
For the other problem, inserting an align environment, unfortunately I don't have a solution. Indeed, just changing
\opaqueblock<#1>[\wd\mybox]{\begin{equation}\BODY\end{equation}}
with
\opaqueblock<#1>[\wd\mybox]{\begin{align}\BODY\end{align}}
is not sufficient. Actually, it works with the example provided above, but if you change
\begin{cdyn}{3-}
\sum_{l _1+\dots+ l _p=l}\prod^p_{i=1} \binom{n_i}{l _i}+
\sum_{l _1+\dots+ l _p=l}\prod^p_{i=1} \binom{n_i}{l _i}\label{eq:sum}
\end{cdyn}
into
\begin{cdyn}{3-}
\sum_{l _1+\dots+ l _p=l}\prod^p_{i=1} \binom{n_i}{l _i}\\
\sum_{lu _1+\dots+ l _p=l}\prod^p_{i=1} \binom{n_i}{l _i}\label{eq:sum}
\end{cdyn}
you will receive these errors
! LaTeX Error: There's no line here to end.
See the LaTeX manual or LaTeX Companion for explanation.
Type H <return> for immediate help.
...
l.54 \end{frame}
Your command was ignored.
Type I <command> <return> to replace it with another command,
or <return> to continue without it.
! Missing $ inserted.
<inserted text>
$
l.54 \end{frame}
I've inserted a begin-math/end-math symbol since I think
you left one out. Proceed, with fingers crossed.
! LaTeX Error: Something's wrong--perhaps a missing \item.
See the LaTeX manual or LaTeX Companion for explanation.
Type H <return> for immediate help.
...
l.54 \end{frame}
Try typing <return> to proceed.
If that doesn't work, type X <return> to quit.
! Missing $ inserted.
<inserted text>
$
l.54 \end{frame}
I've inserted a begin-math/end-math symbol since I think
you left one out. Proceed, with fingers crossed.
The problem here is how the box is measured:
\sbox{\mybox}{$\BODY + \qquad (1)$}%
does not work with environments that break the line (I suppose) and I don't know how to push something like that in a box and measure its width. Of course, you could always do it manually:
\begin{center}
\begin{dynblock}
\opaqueblock<3->[0.8\textwidth]{%
\begin{align}
\sum_{l _1+\dots+ l _p=l}\prod^p_{i=1} \binom{n_i}{l _i}\\
\sum_{lu _1+\dots+ l _p=l}\prod^p_{i=1} \binom{n_i}{l _i}\label{eq:sum}
\end{align}
}
\end{dynblock}
\end{center}
A mwe for completeness:
\documentclass[t]{beamer}
\usepackage{lmodern}
\usetheme{Madrid}
\usepackage[customcolors,shadow,roundedcorners]{dynblocks}
% setting the block body color
\usebeamercolor{block body}
\definecolor{my block body}{named}{bg}
\setbordercolor{my block body}
\setblockcolor{my block body}
% new enviroment always centered
\usepackage{environ}
\newsavebox\mybox
% new environment cdyn: #1 => overlay specification
\NewEnviron{cdyn}[1]{%
\sbox{\mybox}{$\BODY \qquad (1)$}%
\begin{center}
\begin{dynblock}
\opaqueblock<#1>[\wd\mybox]{\begin{equation}\BODY\end{equation}}
\end{dynblock}
\end{center}
}{}%
\begin{document}
\begin{frame}{Test}
\abovedisplayskip=0pt
\begin{cdyn}{1-}
c^2=a^2+b^2
\end{cdyn}
\begin{cdyn}{2-}
x+y=400
\end{cdyn}
\begin{center}
\begin{dynblock}
\opaqueblock<3->[0.35\textwidth]{%
\begin{align}
\sum_{l _1+\dots+ l _p=l}\prod^p_{i=1} \binom{n_i}{l _i}\\
\sum_{lu _1+\dots+ l _p=l}\prod^p_{i=1} \binom{n_i}{l _i}\label{eq:sum}
\end{align}
}
\end{dynblock}
\end{center}
\begin{cdyn}{4-}
q_{n+1}=q_n-\Delta_n+\theta_n \qquad \Delta_n=
\begin{cases}
1 \quad q_n>0\\
0 \quad q_n=0
\end{cases}
\end{cdyn}
\only<4->{I'm referring to \eqref{eq:sum}.}
\end{frame}
\end{document}
The result:
