[Tex/LaTex] Can’t get split rectangle to shrink small enough in this TikZ picture

tikz-pgf

I'm having problem with a TikZ picture – I've got rectangles that I've split, but for some reason the split rectangles are a bit larger than the other rectangles, causing the the alignment to get messed up:

enter image description here

Any ideas on how to solve this? I've included the code below.

\documentclass[a4paper, 11pt]{article}

\usepackage[rgb,hyperref]{xcolor}
\usepackage{tikz}

% Define colors
\definecolor{shade1}{rgb}{0.9, 0.9, 0.9}
\definecolor{shade2}{rgb}{0.75, 0.75, 0.75}
\definecolor{shade3}{rgb}{0.5, 0.5, 0.5}
\definecolor{shade4}{rgb}{0.35, 0.35, 0.35}

% Load TikZ libraries
\usetikzlibrary{shapes,arrows}
\usetikzlibrary{fit}
\usetikzlibrary{backgrounds}
\usetikzlibrary{positioning}
\usetikzlibrary{calc}

% Text settings
\newcommand{\figureTextSize}{\tiny}

% Figure element lengths
\newlength{\gpgpuElemSep}
\setlength{\gpgpuElemSep}{1mm}
\newlength{\gpgpuElemSize}
\setlength{\gpgpuElemSize}{8mm}

% TikZ styles
\newcommand{\arrowStyle}{stealth}
\newcommand{\bendAngle}{45}
\newcommand{\lineThickness}{semithick}
\tikzstyle{box} = [%
  draw,
  rectangle,
  \lineThickness,
]



\begin{document}
\begingroup
\figureTextSize
\begin{tikzpicture}[%
    every node/.style={%
      node distance=0.375\gpgpuElemSep,
    },
    component/.style={%
      box,
      minimum size=0.42\gpgpuElemSize,
      inner sep=0pt,
    },
    alu/.style={%
      component,
      fill=shade1,
    },
    controlcache/.style={%
      component,
      rectangle split,
      rectangle split parts=2,
      rectangle split part fill={shade2, shade3},
    },
    memory/.style={%
      box,
      fill=shade3,
      minimum height=0.5\gpgpuElemSize,
      inner sep=0pt,
    },
  ]
  % Rows of ALUs, control logics and caches
  \foreach \i in {1, ..., 7} {%
    \ifnum \i=1
      \node [controlcache] (cc\i) {};
    \else
      \pgfmathtruncatemacro\prevCC{\i-1}
      \node [controlcache, below=of cc\prevCC] (cc\i) {};
    \fi
    \foreach \j in {1, ..., 7} {%
      \ifnum \j=1
        \node [alu, right=of cc\i] (alu\j) {};
      \else
        \pgfmathtruncatemacro\prevAlu{\j-1}
        \node [alu, right=of alu\prevAlu] (alu\j) {};
      \fi

    }
  }

  % Memory
  \path let \p1 = (cc7.south west),
            \p2 = (alu7.north east)
         in
           node [%
             memory,
             minimum width=\x2-\x1-\pgflinewidth,
             below right,
           ] at ([%
             yshift={-2\gpgpuElemSep},
           ] cc7.south west) (memory) {Memory};
\end{tikzpicture}
\endgroup
\end{document}

Best Answer

You can reset the minimum size options of the rectangle split parts as explained in How to change the height of just one nodepart in TikZ? using 

rectangle split every empty part={}

and then, to get the parts to have the correct height, set

rectangle split empty part height=0.21\gpgpuElemSize-\pgflinewidth

(i.e. half the desired height, minus the thickness of the line, to account for the added size).

enter image description here

\documentclass[a4paper, 11pt]{article}

\usepackage[rgb,hyperref]{xcolor}
\usepackage{tikz}

% Define colors
\definecolor{shade1}{rgb}{0.9, 0.9, 0.9}
\definecolor{shade2}{rgb}{0.75, 0.75, 0.75}
\definecolor{shade3}{rgb}{0.5, 0.5, 0.5}
\definecolor{shade4}{rgb}{0.35, 0.35, 0.35}

% Load TikZ libraries
\usetikzlibrary{shapes,arrows}
\usetikzlibrary{fit}
\usetikzlibrary{backgrounds}
\usetikzlibrary{positioning}
\usetikzlibrary{calc}

% Text settings
\newcommand{\figureTextSize}{\tiny}

% Figure element lengths
\newlength{\gpgpuElemSep}
\setlength{\gpgpuElemSep}{1mm}
\newlength{\gpgpuElemSize}
\setlength{\gpgpuElemSize}{8mm}

% TikZ styles
\newcommand{\arrowStyle}{stealth}
\newcommand{\bendAngle}{45}
\newcommand{\lineThickness}{semithick}
\tikzstyle{box} = [%
  draw,
  rectangle,
  \lineThickness,
]



\begin{document}
\begingroup
\figureTextSize
\begin{tikzpicture}[%
    every node/.style={%
      node distance=0.375\gpgpuElemSep,
    },
    component/.style={%
      box,
      minimum size=0.42\gpgpuElemSize,
      inner sep=0pt,
    },
    alu/.style={%
      component,
      fill=shade1,
    },
    controlcache/.style={%
      component,
      rectangle split,
      rectangle split parts=2,
      rectangle split part fill={shade2, shade3},
      rectangle split every empty part={},
      rectangle split empty part height=0.21\gpgpuElemSize-\pgflinewidth,
    },
    memory/.style={%
      box,
      fill=shade3,
      minimum height=0.5\gpgpuElemSize,
      inner sep=0pt,
    },
  ]
  % Rows of ALUs, control logics and caches
  \foreach \i in {1, ..., 7} {%
    \ifnum \i=1
      \node [controlcache] (cc\i) {};
    \else
      \pgfmathtruncatemacro\prevCC{\i-1}
      \node [controlcache, below=of cc\prevCC] (cc\i) {};
    \fi
    \foreach \j in {1, ..., 7} {%
      \ifnum \j=1
        \node [alu, right=of cc\i] (alu\j) {};
      \else
        \pgfmathtruncatemacro\prevAlu{\j-1}
        \node [alu, right=of alu\prevAlu] (alu\j) {};
      \fi

    }
  }

  % Memory
  \path let \p1 = (cc7.south west),
            \p2 = (alu7.north east)
         in
           node [%
             memory,
             minimum width=\x2-\x1-\pgflinewidth,
             below right,
           ] at ([%
             yshift={-2\gpgpuElemSep},
           ] cc7.south west) (memory) {Memory};
\end{tikzpicture}
\endgroup
\end{document}

Addendum (by Andrew Stacey): The fact that the line width correct is \pgflinewidth surprised me; I expected it to be either .5*\pgflinewidth or not needed at all. So I did a little investigation and discovered a crucial difference between the rectangle split empty part height and the minimum height keys. The minimum height key, when given to a rectangular node and assuming that there's no funny business with the inner sep, is the distance between the top and bottom lines of the rectangle. This is independent of the line thickness. The rectangle split empty part height is the height of the internal box which takes into account the line width. So if we set each to be 1cm, then for a rectangular node, PGF will draw a rectangle with height 1cm, then it will look at the options as to whether to draw it or fill it, and (in particular) what line width to use. For a rectangle split, on the other hand, PGF will draw a rectangle such that when it is drawn, the inside of the drawn rectangle has height 1cm.

Here's a picture to show that. The background lines are 1cm apart, the red and cyan lines are guide lines. The first two yellow boxes are drawn using the rectangle split shape (the second only has one part). The second two are drawn as rectangular nodes. In each case, the corresponding key has been set to either 1cm or 2cm as appropriate. The second and third boxes are placed so that their south anchor is at the relevant coordinate, which has been pushed down by half the line width. All of the arrows are 1cm in length.

rectangular nodes

Here's the code (not particularly elegant!):

\documentclass{article}

\usepackage{tikz}
\usetikzlibrary{shapes}

\begin{document}
\begin{tikzpicture}[line width=2mm]
\begin{scope}[every path/.style={double=orange,line width=.9mm,double distance=.2mm}]
\draw (-.5,0) -- ++(4,0);
\draw (-.5,-1) -- ++(4,0);
\draw (-.5,1) -- ++(4,0);
\end{scope}
\draw[cyan] (0,0) -- +(0,-1);
\draw[red] (0,0) -- +(0,1);
\node[
  draw=yellow,
  inner sep=0pt,
  minimum width=4mm,
  rectangle split,
  rectangle split parts=2,
  rectangle split part fill={green,green},
  rectangle split every empty part={},
  rectangle split empty part height={1cm},
] at (.75,0) {};
\node[
  draw=yellow,
  inner sep=0pt,
  minimum width=4mm,
  rectangle split,
  rectangle split parts=1,
  rectangle split part fill={green},
  rectangle split every empty part={},
  rectangle split empty part height={1cm},
  anchor=south,
]  at (1.5,-1mm) {};
\node[
  rectangle,
  draw=yellow,
  inner sep=0pt,
  minimum width=4mm,
  minimum height=2cm,
  fill=green,
] at (2.25,0) {};
\node[
  draw=yellow,
  inner sep=0pt,
  minimum width=4mm,
  rectangle,
  minimum height=1cm,
  fill=green,
  anchor=south,
] at (3,-1mm) {};
\draw[thick,<->] (0,0) -- ++(0,1);
\draw[thick,<->] (0,0) -- ++(0,-1);
\draw[thick,<->] (.75,0) ++(0,1mm) -- ++(0,1);
\draw[thick,<->] (.75,0) ++(0,-1mm) -- ++(0,-1);
\draw[thick,<->] (1.5,0) ++(0,1mm) -- ++(0,1);
\draw[thick,<->] (2.25,0) -- ++(0,1);
\draw[thick,<->] (2.25,0) -- ++(0,-1);
\draw[thick,<->] (3,0) -- ++(0,1);
\end{tikzpicture}
\end{document}
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