chart.tex

\documentclass{article}
\usepackage{calc}
\usepackage{ifthen}
\usepackage{tikz}
\usepackage{txfonts}
\begin{document}
\newcommand{\slice}[5]{\pgfmathparse{0.5*#1+0.5*#2}\let\midangle\pgfmathresult 
% slice
\draw[thick,fill=blue!#5!white] (0,0) -- (#1:1) arc (#1:#2:1) -- cycle;
% outer label
\node[label=\midangle:#4] at (\midangle:1) {};
% inner label
\pgfmathparse{min((#2-#1-10)/110*(-0.3),0)} \let\temp\pgfmathresult \pgfmathparse{max(\temp,-0.5) + 0.8} \let\innerpos\pgfmathresult \node[rectangle, fill=white] at (\midangle:\innerpos) {#3};}
\begin{tikzpicture}[scale=3]
\newcounter{a}
\newcounter{b}
\foreach \p/\t in {
7/OpenSUSE,6/Fedora,6/Slackware,30/Ubuntu,5/Chakra,5/Gentoo,26/Outras,15/Debian
} {
\setcounter{a}{\value{b}} \addtocounter{b}{\p} \slice{\thea/100*360} {\theb/100*360} {\p\%}{\t}{\theb}
}
\end{tikzpicture}
\end{document}