metapost annotation

Metapost is a powerful tool for drawing, but not sure if it's more easier than tikz for annotation. Is it possible to draw this annotation graph with metapost?

tikz code:

\documentclass[tikz]{standalone}

\usepackage{tikz}
\usetikzlibrary{decorations.pathreplacing}

\tikzstyle{boxa} = [top color=white,bottom color=blue!20!]
\tikzstyle{boxb} = [top color=white,bottom color=red!20!]
\tikzstyle{curly} = [decorate,decoration={brace,amplitude=10pt},xshift=0pt,yshift=2pt]                 
% Input:
%   #1 Line offset (optional)
%   #2 Line angle
%   #3 line start offset
%   #4 Line end offset
%   #5 Line label
% Example:
%   \lineann[1]{30}{1}{4}{$L_1$}
\newcommand{\lineann}[5][0.5]{%
    \begin{scope}[rotate=#2,blue,inner sep=2pt]
        \draw[dashed, blue!40] (#3,0) -- +(0,#1)
            node [coordinate, near end] (a) {};
        \draw[dashed, blue!40] (#4,0) -- +(0,#1)
            node [coordinate, near end] (b) {};
        \draw[|<->|] (a) -- node[fill=white] {#5} (b);
    \end{scope}
}
\begin{document}

\begin{tikzpicture}[scale=1]
\def\dx{2.0}
\def\dy{.5}
\filldraw[thick,boxa] (0,0) rectangle node{$P_1$} +(\dx,\dy);
\filldraw[thick,boxa] (\dx,0) rectangle node{$P_2$} +(\dx,\dy);
\filldraw[thick,boxa] (2*\dx,0) rectangle node{$P_3$} +(\dx,\dy);
\filldraw[thick,boxb] (3*\dx,0) rectangle node{$P_4$} +(\dx,\dy);

\draw [curly] (0,\dy)--(4*\dx,\dy) node [black,midway,yshift=14pt] {\footnotesize $T_0$};
\lineann[-10pt]{0}{3*\dx}{4*\dx}{\footnotesize $T_1$}
\end{tikzpicture}
\end{document}

Output: