%
% centerpg.sty
%
% Optically centers a page on a sheet of paper.
%
% By Charles Duan
%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
\ProvidesPackage{centerpg}[2004/04/06 Optical centering of text on a page]
%
% This is used to store the page.
\newbox\@opticalcbox
%
% Produces a box the size of the full height of the paper, and places the
% material in this environment into that box.
\newenvironment{centeredpage*}{%
    \clearpage
    \thispagestyle{empty}
    \setbox\@opticalcbox\vbox to \paperheight\bgroup
}{%
    \egroup
    \nointerlineskip \topskip\z@ \flushbottom
    % Put in a fake rule so glue isn't killed
    \hrule\@height\z@\penalty\@M
    \vbox to \textheight{%
	\@tempdima\topmargin
	    \advance\@tempdima\headheight\advance\@tempdima\headsep
	    \advance\@tempdima 1in
	\vskip-\@tempdima
	\vbox to \paperheight{%
	    \box\@opticalcbox
	}%
	\vss
    }%
    % End the page
    \if@twoside\cleardoublepage\else\newpage\fi
    \ignorespacesafterend
}
\newenvironment{centeredpage}{%
    \begin{centeredpage*}%
	\vskip \z@\@plus\@m fil\relax
	\hb@xt@\textwidth\bgroup\hfil\vbox\bgroup
}{%
	\egroup\hfil\egroup\setbox\z@\lastbox
	\@tempcnta\ht\z@ \advance\@tempcnta\dp\z@
	\box\z@
	\@tempcntb\paperheight \divide\@tempcntb -500\relax
	\divide\@tempcnta\@tempcntb
	\advance\@tempcnta 1500\relax
	\vskip \z@\@plus\@tempcnta fil\relax
    \end{centeredpage*}%
    \ignorespacesafterend
}

\endinput