How to know if a tikz picture is empty

Question

In my code some pictures should be displayed if any condition is satisfied.

The conditional must necessarily be placed within the picture environment.

The question is how to insert a line break in the text ONLY if the picture actually took place.

A MWE:

\documentclass{article}
\usepackage{tikz}

\newcommand{\picturexample}[1]{%
\begin{tikzpicture}
  \ifodd#1              % In practice, a PGF/TikZ's check command
    \draw (0,0) circle (1);
  \fi
\end{tikzpicture}}

\newcount\n

\begin{document}

\loop
  \picturexample{\n}%
  \\                    % this should happen only when the picture "exists"
  \advance\n1
\ifnum\n<10\repeat

\end{document}

Answer 1

You can store the picture in a box, measure it, and if it has no content then all its dimensions are 0. This does not work for overlay pictures, though.

\documentclass{article}
\usepackage{tikz}

\newcommand{\picturexample}[1]{%
\begin{tikzpicture}
  \ifodd#1              % In practice, a PGF/TikZ's check command
    \draw (0,0) circle (1);
  \fi
\end{tikzpicture}}

\newcount\n

\begin{document}
\noindent
\loop
  \setbox0\hbox{\picturexample{\n}}%
  \ifdim\dimexpr\wd0+\ht0+\dp0>0pt\relax
    \usebox0\\
  \fi                       % this should happen only when the picture "exists"
  \advance\n1
\ifnum\n<10\repeat
\end{document}