Centering and Reference Coordinates

Question

Question 1 Can I define reference coordinates for x and y and then use these coordinates to adjust my figures inside a Tikz picture?

As an illustration, if I want to readjust all the rectangles in this picture to the left by 0.25, I will have to manually change the coordinates of each box or each \foreach instruction. Please advise a better solution for this. Can I define coordinates in the starting such as x = 0 and y = 0 then if I have to readjust the rectangles I just change x to -0.25 and y to -0.25.

Question 2 How can I center a tikzpicture in one column of the conference paper ?

MWE

\ifCLASSINFOpdf

\else
\fi
\usepackage[usenames,dvipsnames]{color}
\usepackage[T1]{fontenc}
\usepackage{tikz}
\usetikzlibrary{positioning}
\usetikzlibrary{arrows}
\usetikzlibrary{shapes.multipart}
\usepackage[caption=false]{subfig}
\usepackage{tabularx,tikz}


\hyphenation{op-tical net-works semi-conduc-tor}


\begin{document}

\title{Bare Demo of IEEEtran.cls for Conferences}

\maketitle

\IEEEpeerreviewmaketitle

\section{Introduction}
I wish you the best of success.

\begin{tikzpicture} 
%Can I give a reference coordinate such as x = 0 and y = 0 and then draw figures
%based on that reference points through out the picture?

\draw [rounded corners](0,0) rectangle +(9,6);

\draw [rounded corners](0.15,0.5) node[above right, font =\small,align=center,text width = 2cm]{YYYY} rectangle +(2.25,5);

\foreach \x in {2.5}
    \foreach \y in {0.5,3,4.5}
    {
    \draw [rounded corners] (\x,\y) rectangle +(6.35,1);

    }

\foreach \x in {2.75,4.25,5.75,7.25}
    \foreach \y in {0.9,3.4,4.9}
    {
    \draw [rounded corners] (\x, \y) node[above right, font=\scriptsize,text width = 1.8cm] {XXX} rectangle +(1.2,0.5);
    }

\end{tikzpicture}

\end{document}

Thanks!

Answer 1

You could use calc:

\documentclass[tikz]{standalone}
\usetikzlibrary{positioning, calc}

\begin{document}

  \begin{tikzpicture}
    \coordinate (ref) at (0,0);
    \draw [rounded corners](ref) rectangle +(9,6);
    \draw [rounded corners]($(ref) + (0.15,0.5)$) node[above right, font =\small,align=center,text width = 2cm]{YYYY} rectangle +(2.25,5);
    \foreach \x in {2.5}
    \foreach \y in {0.5,3,4.5}
    {
      \draw [rounded corners] ($(ref) + (\x,\y)$) rectangle +(6.35,1);
    }
    \foreach \x in {2.75,4.25,5.75,7.25}
    \foreach \y in {0.9,3.4,4.9}
    {
      \draw [rounded corners] ($(ref) + (\x, \y)$) node[above right, font=\scriptsize,text width = 1.8cm] {XXX} rectangle +(1.2,0.5);
    }
    \coordinate (ref) at (-0.25,-0.25);
    \tikzset{color=red}
    \draw [rounded corners](ref) rectangle +(9,6);

    \draw [rounded corners]($(ref) + (0.15,0.5)$) node[above right, font =\small,align=center,text width = 2cm]{YYYY} rectangle +(2.25,5);
    \foreach \x in {2.5}
    \foreach \y in {0.5,3,4.5}
    {
      \draw [rounded corners] ($(ref) + (\x,\y)$) rectangle +(6.35,1);

    }
    \foreach \x in {2.75,4.25,5.75,7.25}
    \foreach \y in {0.9,3.4,4.9}
    {
      \draw [rounded corners] ($(ref) + (\x, \y)$) node[above right, font=\scriptsize,text width = 1.8cm] {XXX} rectangle +(1.2,0.5);
    }
  \end{tikzpicture}

\end{document}