LaTeX 插图加载宏包。支持 LaTeX - DVIPDFMx; pdfLaTeX; XeLaTeX 三种编译方式，支持 eps/pdf/jpg/png 等图片格式。
% Put this snippet in your preamble.
\usepackage{ifpdf, ifxetex}
\ifxetex
\usepackage{graphicx}
\else
\ifpdf
\usepackage{graphicx}
\usepackage{epstopdf}
\else
\usepackage[dvipdfm]{graphicx}
\usepackage{bmpsize}
\fi
\fi