[Tex/LaTex] Centering images in a TikZ matrix node

tikz-pgf

I would like to construct a figure using a collection of images/icons as nodes.

I'd like to be able to use matrix, relative positioning and draw arrows between them.

I'm a bit stumped as to why my current solution (see below) displays the images centered at the lower left corner of node boxes, rather than at the center.

I've found that img./style={align=center} solves the problem of centering them horizontally.

Any ideas as on how to align them vertically as well?

Use of pgfdeclareimage and pgfbox are not required, but just a part of my attempt to get it to work.

Code:

\documentclass{article}

\usepackage{tikz}
\usetikzlibrary{arrows,positioning} 

\begin{document}
% a bunch of images at 64pxx64px
\pgfdeclareimage{observer}{figures/engineer.png}
\pgfdeclareimage{home}{figures/home.png}
\pgfdeclareimage{user}{figures/user.png}
\pgfdeclareimage{framework}{figures/user.png}

\tikzset{
  % style for inserting images as nodes
  img/.style={
    text width=2cm,
    text height=2cm,
    rectangle,
    align=center,
    draw} % only for debugging..
}

\begin{tikzpicture}
  \matrix[nodes=img, column sep=0.2cm]{
    \node[] (user) {\pgfbox[center,center]{\pgfuseimage{user}}}; &
    \node[ right=of user] (home) {\pgfbox[center,center]{\pgfuseimage{home}}}; &
    \node[ right=of home] (obse) {\pgfbox[center,center]{\pgfuseimage{observer}}}; \\
  };
\end{tikzpicture}
\end{document}

Result:

result

Best Answer

This is one possibility as suggested by Zarko.

\documentclass[tikz,border=4mm]{standalone}
\usetikzlibrary{matrix}
\newcommand{\ing}[1]{\includegraphics[width=2cm]{#1}}
\tikzset{
  % style for inserting images as nodes
  img/.style={
    text width=2cm,
    %text height=2cm,                 %% don't use this
    inner sep=0pt,     %% use this
    outer sep=0pt,     %% and this
    rectangle,
    align=center,
    draw,thick} % only for debugging..
}
\begin{document}
\begin{tikzpicture}
  \matrix[matrix of nodes,nodes=img, column sep=0.2cm]{
    \ing{example-image-a} &
    \ing{example-image-b} &
    \ing{example-image-c} \\
  };
\end{tikzpicture}
\end{document}

enter image description here

Notes:

Don't use text height as it will spoil the show.
Use width value in \ing and text width as you wish.
inner and outer sep with zero value give better look.

Related Solutions

[Tex/LaTex] Some problems drawing linked lists with TikZ’s matrix library

You can use {} instead of \mbox{} to save yourself some typing when creating empty nodes. As ipavlic points out in his comment, you can also use the nodes in empty cells key. This means that you can't specify all the extra gaps between the columns in the first row, because that would create a lot of incorrect empty nodes. Rather, you have to specify the extra gaps in the row where they are first used.
You need to use column 1/.style={nodes={minimum height=0.8cm}} to change the node behaviour. If you don't use nodes=..., you are basically changing the options that apply to the matrix as a whole, not the nodes (see Matrix of nodes column style inconsistency for more on that).
It doesn't change the center, but rather the label is assigned the node name (M-1-1). You can prevent this by adding the option every label/.append style={name={}} to the matrix. (see example at the end of the answer for a demonstration)
That's the normal behaviour of specifying a node name without an anchor. Quote from the pgfmanual, section 16.11: "When you say (x)--(1,1), the -- path operation will not draw a line from the center of x, but from the border of x in the direction going towards (1,1)"
In order to make the lines overlap, the distance between the columns has to be -\pgflinewidth. See TikZ matrix as a replacement for tabular.
In How should I draw a singly/double linked list?, the *- line starts at the horizontal position of <node>.two of the multipart node, which is not the center of the second node part, but actually shifted slightly to the left (replace *-> with -- to see where the line actually starts). In the case of the *- arrow style, that's a convenient thing. Since you don't use multipart nodes, but one node for each rectangle, you don't have that anchor, and will have to resort to using shorten < = -2pt.

Here's your code with the suggested changes:

\documentclass{standalone} 
\usepackage{tikz} 
\usetikzlibrary{matrix,arrows,fit} 

\tikzset{circarrow/.style={
        *->,
        shorten <=-2pt
    }
}

\begin{document} 
\begin{tikzpicture}[>=stealth] 
\matrix (M) [matrix of nodes,% 
   column sep=-\pgflinewidth,% 
   row sep=1mm,% 
   nodes in empty cells,
   nodes={draw, fill=gray!20,%
     minimum width=.5cm, outer sep=0pt,% 
     minimum height=.7cm, anchor=center}, 
   column 1/.style={nodes={minimum height=.8cm}}]%
{ 
  &[2mm] 2 & &[2mm] 5 & /  \\ 
 & 1 & & 5 & &[2mm] 3 & &[2mm] 4 & / \\ 
 & 2 & & 5 & & 3 & /\\ 
}; 

\foreach \i in {1,2,3}{ 
 \path (M-\i-1) [late options={label=left:\i}]; 
 \draw[->] (M-\i-1)--(M-\i-2.west); 
 \draw[->] (M-\i-3.center)--(M-\i-4.west); 
} 

\draw[->] (M-2-5.center)--(M-2-6.west); 
\draw[->] (M-2-7.center)--(M-2-8.west); 
\draw[->] (M-3-5.center)--(M-3-6.west); 

\begin{scope}[yshift=-3cm]
\matrix (M) [matrix of nodes,% 
   column sep=-\pgflinewidth,% 
   row sep=1mm,% 
   nodes in empty cells,
   nodes={draw, fill=gray!20,%
    minimum width=.5cm, outer sep=0pt,% 
    minimum height=.7cm, anchor=center}, 
   column 1/.style={nodes={minimum height=.8cm}},
   every label/.append style={name={}}]%
{ 
 |[label=left:1]| &[2mm] 2 & &[2mm] 5 & /  \\ 
 |[label=left:2]|& 1 & & 5 & &[2mm] 3 & &[2mm] 4 & / \\ 
 |[label=left:3]| & 2 & & 5 & & 3 & / & & \\ 
}; 

\foreach \i in {1,2,3}{ 
 %\path (M-\i-1) [late options={label=left:\i}]; 
 \draw[->] (M-\i-1)--(M-\i-2.west); 
 \draw[->] (M-\i-3.center)--(M-\i-4.west); 
} 

\draw[circarrow] (M-2-5.center)--(M-2-6.west); 
\draw[circarrow] (M-2-7.center)--(M-2-8.west); 
\draw[circarrow] (M-3-5.center)--(M-3-6.west); 

\end{scope}
\end{tikzpicture} 
\end{document}

Example of how label changes which node is named in the matrix (instead of expanding the node):

labels in matrices

\documentclass{standalone} 
\usepackage{tikz} 
\usetikzlibrary{matrix,fit} 


\begin{document} 
\begin{tikzpicture}
\matrix (M) [matrix of nodes,% 
   row sep=1mm,% 
   nodes={draw, fill=gray!20,%
    minimum width=.5cm, outer sep=0pt,% 
    minimum height=.7cm, anchor=center}
   ]%
{ 
 |[label=left:1]| &[2mm] 2\\
 |[label={[name=none]left:2}]|& 1\\
}; 

\foreach \i in {1,2}{ 
 \draw[->] (M-\i-1)--(M-\i-2.west);
 \node [fit=(M-\i-1),draw,red] {};
} 


\end{tikzpicture}

[Tex/LaTex] How to define the default vertical distance between nodes

I don't really get the question so I hope this is what you wanted. If you include a full document (such that we copy paste and see the problem on our systems) things are much more easier.

Here, you can change the default setting within a scope but your block style had a node distance which was resetting every time it is issued. I've made it 2mm such that we can see the difference easier.

\documentclass[tikz]{standalone}
\usetikzlibrary{arrows,shapes.geometric,positioning}

\begin{document}
\begin{tikzpicture}[decision/.style={diamond, draw, text width=4.5em, text badly centered, node distance=3.5cm, inner sep=0pt},
                    block/.style   ={rectangle, draw, text width=6em, text centered, rounded corners, minimum height=4em, minimum height=2em},
                    cloud/.style   ={draw, ellipse, minimum height=2em},
                    line/.style    ={draw,-latex'},
                    node distance = 1cm, 
                    auto]
    \node [block] (1st) {1st};
    \node [block, right= of 1st]  (2nd1) {2nd1};
\begin{scope}[node distance=2mm and 10mm]%Here we change it for everything inside this scope
    \node [block, above= of 2nd1] (2nd2) {2nd2};
    \node [block, below= of 2nd1] (2nd3) {2nd3};
    \node [block, right= of 2nd1] (3rd1) {3rd1};
    \node [block, above= of 3rd1] (3rd2) {3rd2};
    \node [block, above= of 3rd2] (3rd3) {3rd3};
\end{scope}
    \node [block, below= of 3rd1] (3rd4) {3rd4};
    \node [block, below= of 3rd4] (3rd5) {3rd5};

    \path [line] (1st) -- (2nd1);
    \path [line] (2nd1) -- (2nd2);
    \path [line] (2nd1) -- (2nd3);
    \path [line] (2nd2) -- (3rd3);
    \path [line] (2nd1) -- (3rd1);
    \path [line] (1st) -- (2nd1);
\end{tikzpicture}
\end{document}

enter image description here

Best Answer

Related Solutions

[Tex/LaTex] Some problems drawing linked lists with TikZ’s matrix library

[Tex/LaTex] How to define the default vertical distance between nodes

Related Question