# Creating thicker Tikz mindmap connectors

I'm running MiKTeX 2.9, on a Windows 7 machine. My pdflatex compilation log lists:

pgf 2008/01/15 v2.10 (rcs-revision 1.12)


I am using TikZ's mindmap library to draw some graphics and I quite like the output.

I am trying to tweak the circle connection bar style of the connector between two nodes. In particular I'd like change the thickness of the connection bar between nodes at one level (but not any others).

• The first image displays the entire example mindmap (built from the working example below)

• The second image displays the normal connectors created by the mindmap library's default styles

• The third image is a mockup of the kind of effect I am trying to create.

I've read the documentation in the pgf manual (ver 2.10) for the mindmap library, and have tried to override the settings for the circle connection bar using the decoration option (e.g decoration={start radius=1cm,end radius=.5cm,amplitude=2mm,angle=30}), however no matter what value I give the amplitude setting I see no change in the output. Changes to angle and start/end radius do effect the first and last part of the connector, but the rectangle in between never changes width.

I've had success (in the sense of effecting a change) by:

• placing the decoration option before a node's children (thereby effecting all children and grandchildren), e.g. \node [root concept] {Team\\Foo}[decoration={angle=45}]

• specifying a \path (node1) to[circle connection bar] (node2); explicitly between two named nodes (not ideal, as explicitly drawing connections eliminates a large benefit of using the mindmap library in the first place)

• and as part of the every circle connection bar style (specified in the tikzpicture or scope)

I don't want to have to explicitly specify starting and ending radii, as the mindmap library normally calculates these automatically and I'd like to be able to change the node sizes and have the connection bars adjust without anymore manual intervention (just with thicker lines than normal).

My questions come down to these:

• How do I change the amplitude/thickness of the connection bar (perhaps this will require also explicitly setting an angle)?

• How do I apply this modification to the connections at one level only? I can set the modification at any level and effect all levels below, but can I either restrict the modification to only one level to begin with, or otherwise reset the connection bar styles back to default for lower levels (i.e. after explicitly setting decoration={...}, how do I undo that)?

Working example:

\documentclass[tikz, preview=true, border=2mm]{standalone}

\renewcommand*\familydefault{\sfdefault}

\usepackage{tikz}
\usetikzlibrary{mindmap,trees,shadows}

\begin{document}

\begin{tikzpicture}
[decoration={start radius=1cm, end radius=.5cm,amplitude=3mm,angle=30}]

% Define experience colors
\colorlet{afcolor}{blue!50}
\colorlet{mdcolor}{red!75}
\colorlet{nmndcolor}{orange!80}
\colorlet{nmescolor}{teal!70!green}
\colorlet{citscolor}{violet!75}

\begin{scope}[mindmap,
every node/.style={concept, circular drop shadow, minimum size=0pt,execute at begin node=\hskip0pt, font=\bfseries},
root concept/.append style={
concept color=black, fill=white, line width=1.5ex, text=black, font=\huge\scshape\bfseries,},
level 1 concept/.append style={font=\bfseries},
text=white,
partner/.style={concept color=blue!80!black},
air force/.style={concept color=afcolor},
metadata/.style={concept color=mdcolor},
nmnd/.style={concept color=nmndcolor},
nmes/.style={concept color=nmescolor},
cits/.style={concept color=citscolor},
grow cyclic,
level 1/.append style={level distance=6.2cm,sibling angle=45},
level 2/.append style={level distance=3cm,sibling angle=45}]
\node [root concept] (team) {Team\\Foo}[rotate=202.5] % root
child [partner] { node {Comp 8}
child [nmes] { node {\small NM/ES} }
}
child [partner] { node {Comp 1}
child [metadata] { node {\small Metadata} }
child [air force] { node {\small Air Force} }
child [nmnd] { node {\small NM/ND} }
child [cits] { node {\small CITS} }
child [nmes] { node {\small NM/ES} }
}
child [partner] { node {Comp 2}
child [metadata] { node {\small Metadata} }
}
child [partner] { node (comp3) {Comp 3}
child [air force] { node {\small Air Force} }
child [nmnd] { node {\small NM/ND} }
child [cits] { node (leftmost) {\small CITS} }
child [nmes] { node {\small NM/ES} }
}
child [partner] { node {Comp 4}
child [air force] { node {\small Air Force} }
child [nmes] { node {\small NM/ES} }
}
child [partner] { node {Comp 5}
child [metadata] { node {\small Metadata} }
child [nmnd] { node {\small NM/ND} }
child [nmes] { node {\small NM/ES} }
}
child [partner] { node {Comp 6}
child [air force] { node {\small Air Force} }
child [nmnd] { node {\small NM/ND} }
child [nmes] { node {\small NM/ES} }
}
child [partner] { node {Comp 7}
child [air force] { node {\small Air Force} }
child [nmnd] { node {\small NM/ND} }
child [nmes] { node {\small NM/ES} }
};
\end{scope}

\begin{scope}[xshift=-4.5cm, yshift=-10.5cm,every node/.style={align=left,text=black}]
\matrix[row sep=0pt,column sep=1mm, align=left, nodes={align=left, anchor=west}] {
\fill [afcolor] (0,.25ex) circle (1ex); & \node{Air Force Experience};\\
\fill [mdcolor] (0,.25ex) circle (1ex); & \node{Metadata Environments Development Experience};\\
\fill [nmndcolor] (0,.25ex) circle (1ex); & \node{Network Management and Network Defense Experience};\\
\fill [nmescolor] (0,.25ex) circle (1ex); & \node{Network Management and Enterprise Services Experience};\\
\fill [citscolor] (0,.25ex) circle (1ex); & \node{CITS Information Transport Systems Experience};\\
};
\end{scope}
\end{tikzpicture}

\end{document}

-
Welcome to LaTeX! As new user without image posting privileges simply include the image as normal and remove the ! in front of it to turn it into a link. A moderator or another user with edit privileges can then reinsert the ! to turn it into an image again until you get more rep points. –  percusse Oct 23 '12 at 21:51
@Fareed Maybe you could try to type up a minimal working example (MWE). Your code shows too many styles and unnecessary stuff (for example the legend). I don't think that we need so many children, too. –  Qrrbrbirlbel Nov 2 '12 at 0:24
I had, similar to you, some semi-successful results with the decoration stuff, but not really something that only affects the first level. Interesting enough, the amplitude key doesn't do anything in my experiments … –  Qrrbrbirlbel Nov 2 '12 at 0:31
@Qrrbrbirlbel I will add an MWE when I get a chance. I included the entire graphic to provide context as to to why I want to change the connection styles in the first place, but I agree that it contains a lot of extraneous elements. –  Fareed Nov 5 '12 at 19:48

## 1 Answer

It is a complex problem and unfortunately it has a complex solution. Let's proceed.

1. Why amplitude setting has no effect. This setting is only used for "manual" connections using style simple connection bar, and in this case you have to specify also the initial and final radii (see p.385 of the manual). When you use instead the mindmap style for the whole tree, a special to path is installed which automatically computes the initial and final radii, and the amplitude. You can only specify angles.

The solution for this problem is to write a variant of the code which computes the radii and amplitude, making them to return a bigger value. But then we have to "install" this code in some way for the mindmap style to use it.

2. If we modify the code which installs the to path, the change is global for all the mindmap, so we would get all the connections "thick". Even if we install the new to path only for the first level, its effect is global because it applies also to all child levels from the level in which it is installed. So we need to install the code for the first level and uninstall it for subsequent levels.

3. In order to get shaded connections which fade from the parent color to the child color, tikz uses a special trick. When you set a concept color, the library sets the color of that (child) node, and also installs a code to draw a path from its parent using the style circle connection bar switch color. This style requires one parameter, which is the color of the child node. If we want to install a new code which draws the connection more thick, we have to install it at this point. Thus, this does not depend on the level, but on the use of the key concept color which can happen at any level.

To solve all above problems I devised a solution. It is admittedly ugly and cumbersome but it works, and it is the best I coul do. There is it:

## 1. New macros to compute the radii and amplitude which produce bigger results

Taken the code from tikzlibrarymindmap.code.tex, I wrote the following macros, whose name ends in @b to differentiate them from the original ones. The code is identical except for the numbers 1.6 and .35 which originally were 1.0 and .175. The new values are somewhat arbitrary. You can play with other values to get the look you like the most.

\def\tikz@compute@circle@radii@b{%
\pgf@process{\pgfpointtransformed{\pgfpointanchor{\tikztostart}{center}}}%
\pgf@xa=\pgf@x%
\pgf@process{\pgfpointtransformed{\pgfpointanchor{\tikztostart}{west}}}%
\advance\pgf@xa by-\pgf@x%
\pgf@xa=1.6\pgf@xa\relax%  <<<-----  here
\pgfkeys{/pgf/decoration/start radius/.expanded=\the\pgf@xa}%
\pgf@process{\pgfpointtransformed{\pgfpointanchor{\tikztotarget}{center}}}%
\pgf@xa=\pgf@x%
\pgf@process{\pgfpointtransformed{\pgfpointanchor{\tikztotarget}{west}}}%
\advance\pgf@xa by-\pgf@x%
\pgf@xa=1.6\pgf@xa\relax%  <<<-----  and here
\pgfkeys{/pgf/decoration/end radius/.expanded=\the\pgf@xa}%
}

\def\tikz@compute@segmentamplitude@b{%
\pgf@x=\pgfkeysvalueof{/pgf/decoration/start radius}\relax%
\ifdim\pgf@x>\pgfkeysvalueof{/pgf/decoration/end radius}\relax%
\pgf@x=\pgfkeysvalueof{/pgf/decoration/end radius}\relax%
\fi%
\pgf@x=.35\pgf@x\relax%   <<<----- here
\edef\pgfdecorationsegmentamplitude{\the\pgf@x}%
}


## 2. New styles which "install" and "uninstall" the above macros as part of the computation of the edges.

I define the following two styles, to be used in place of concept color. You have to use thick bar concept color for children which have to be connected with their parent via a thick bar, and standard bar concept color for children which are connected with their parent via a standard thickness bar. Internally these styles redefine the macros used to compute the radii and amplitude, and make the to connection. They are based in style concept color defined in tikzlibrarymindmap.code.tex.

\tikzoption{thick bar concept color}{%
\let\tikz@old@concept@color=\tikz@concept@color%
\let\tikz@old@compute@circle@radii=\tikz@compute@circle@radii%
\let\tikz@compute@circle@radii=\tikz@compute@circle@radii@b%
\let\tikz@old@compute@segmentamplitude=\tikz@compute@segmentamplitude%
\let\tikz@compute@segmentamplitude=\tikz@compute@segmentamplitude@b%
\def\tikz@edge@to@parent@path{
(\tikzparentnode)
to[circle connection bar switch color=from (\tikz@old@concept@color) to (#1)]
(\tikzchildnode)}
\def\tikz@concept@color{#1}%
}
\tikzoption{standard bar concept color}{%
\let\tikz@old@concept@color=\tikz@concept@color%
\let\tikz@compute@circle@radii=\tikz@old@compute@circle@radii%
\let\tikz@compute@segmentamplitude=\tikz@old@compute@segmentamplitude%
\def\tikz@edge@to@parent@path{
(\tikzparentnode)
to[circle connection bar switch color=from (\tikz@old@concept@color) to (#1)]
(\tikzchildnode)}
\def\tikz@concept@color{#1}%
}


## 3. Use in the mindmap

With the above setup, in your mindmap you have to use thick bar concept color for all nodes at the first level, and standard bar concept color for the remaining levels. In your case it is easy, because you have defined specific styles for the different kind of nodes, so you simply need:

[...]
partner/.style={thick bar concept color=blue!80!black},
air force/.style={standard bar concept color=afcolor},
metadata/.style={standard bar concept color=mdcolor},
nmnd/.style={standard bar concept color=nmndcolor},
nmes/.style={standard bar concept color=nmescolor},
cits/.style={standard bar concept color=citscolor},
[...]


## 4. All together now

This is the full code and the result:

\documentclass[tikz, preview=true, border=2mm]{standalone}

\renewcommand*\familydefault{\sfdefault}

\usepackage{tikz}
\usetikzlibrary{mindmap,trees,shadows}

\begin{document}
\makeatletter
\def\tikz@compute@circle@radii@b{%
\pgf@process{\pgfpointtransformed{\pgfpointanchor{\tikztostart}{center}}}%
\pgf@xa=\pgf@x%
\pgf@process{\pgfpointtransformed{\pgfpointanchor{\tikztostart}{west}}}%
\advance\pgf@xa by-\pgf@x%
\pgf@xa=1.6\pgf@xa\relax%
\pgfkeys{/pgf/decoration/start radius/.expanded=\the\pgf@xa}%
\pgf@process{\pgfpointtransformed{\pgfpointanchor{\tikztotarget}{center}}}%
\pgf@xa=\pgf@x%
\pgf@process{\pgfpointtransformed{\pgfpointanchor{\tikztotarget}{west}}}%
\advance\pgf@xa by-\pgf@x%
\pgf@xa=1.6\pgf@xa\relax%
\pgfkeys{/pgf/decoration/end radius/.expanded=\the\pgf@xa}%
}

\def\tikz@compute@segmentamplitude@b{%
\pgf@x=\pgfkeysvalueof{/pgf/decoration/start radius}\relax%
\ifdim\pgf@x>\pgfkeysvalueof{/pgf/decoration/end radius}\relax%
\pgf@x=\pgfkeysvalueof{/pgf/decoration/end radius}\relax%
\fi%
\pgf@x=.35\pgf@x\relax%
\edef\pgfdecorationsegmentamplitude{\the\pgf@x}%
}
\tikzoption{thick bar concept color}{%
\let\tikz@old@concept@color=\tikz@concept@color%
\let\tikz@old@compute@circle@radii=\tikz@compute@circle@radii%
\let\tikz@compute@circle@radii=\tikz@compute@circle@radii@b%
\let\tikz@old@compute@segmentamplitude=\tikz@compute@segmentamplitude%
\let\tikz@compute@segmentamplitude=\tikz@compute@segmentamplitude@b%
\def\tikz@edge@to@parent@path{
(\tikzparentnode)
to[circle connection bar switch color=from (\tikz@old@concept@color) to (#1)]
(\tikzchildnode)}
\def\tikz@concept@color{#1}%
}
\tikzoption{standard bar concept color}{%
\let\tikz@old@concept@color=\tikz@concept@color%
\let\tikz@compute@circle@radii=\tikz@old@compute@circle@radii%
\let\tikz@compute@segmentamplitude=\tikz@old@compute@segmentamplitude%
\def\tikz@edge@to@parent@path{
(\tikzparentnode)
to[circle connection bar switch color=from (\tikz@old@concept@color) to (#1)]
(\tikzchildnode)}
\def\tikz@concept@color{#1}%
}

\makeatother

\begin{tikzpicture}

% Define experience colors
\colorlet{afcolor}{blue!50}
\colorlet{mdcolor}{red!75}
\colorlet{nmndcolor}{orange!80}
\colorlet{nmescolor}{teal!70!green}
\colorlet{citscolor}{violet!75}

\begin{scope}[mindmap,
every node/.style={concept, circular drop shadow, minimum size=0pt,execute at begin node=\hskip0pt, font=\bfseries},
root concept/.append style={
concept color=black, fill=white, line width=1.5ex, text=black, font=\huge\scshape\bfseries,},
level 1 concept/.append style={font=\bfseries},
text=white,
partner/.style={thick bar concept color=blue!80!black},
air force/.style={standard bar concept color=afcolor},
metadata/.style={standard bar concept color=mdcolor},
nmnd/.style={standard bar concept color=nmndcolor},
nmes/.style={standard bar concept color=nmescolor},
cits/.style={standard bar concept color=citscolor},
grow cyclic,
level 1/.append style={level distance=6.2cm,sibling angle=45},
level 2/.append style={level distance=3cm,sibling angle=45},
]
\node [root concept] (team) {Team\\Foo}[rotate=202.5] % root
child [partner] { node {Comp 8}
child [nmes] { node {\small NM/ES} }
}
child [partner] { node {Comp 1}
child [metadata] { node {\small Metadata} }
child [air force] { node {\small Air Force} }
child [nmnd] { node {\small NM/ND} }
child [cits] { node {\small CITS} }
child [nmes] { node {\small NM/ES} }
}
child [partner] { node {Comp 2}
child [metadata] { node {\small Metadata} }
}
child [partner] { node (comp3) {Comp 3}
child [air force] { node {\small Air Force} }
child [nmnd] { node {\small NM/ND} }
child [cits] { node (leftmost) {\small CITS} }
child [nmes] { node {\small NM/ES} }
}
child [partner] { node {Comp 4}
child [air force] { node {\small Air Force} }
child [nmes] { node {\small NM/ES} }
}
child [partner] { node {Comp 5}
child [metadata] { node {\small Metadata} }
child [nmnd] { node {\small NM/ND} }
child [nmes] { node {\small NM/ES} }
}
child [partner] { node {Comp 6}
child [air force] { node {\small Air Force} }
child [nmnd] { node {\small NM/ND} }
child [nmes] { node {\small NM/ES} }
}
child [partner] { node {Comp 7}
child [air force] { node {\small Air Force} }
child [nmnd] { node {\small NM/ND} }
child [nmes] { node {\small NM/ES} }
};
\end{scope}

\begin{scope}[xshift=-4.5cm, yshift=-10.5cm,every node/.style={text=black}]
\matrix[row sep=0pt,column sep=1mm, nodes={anchor=west}] {
\fill [afcolor] (0,.25ex) circle (1ex); & \node{Air Force Experience};\\
\fill [mdcolor] (0,.25ex) circle (1ex); & \node{Metadata Environments Development Experience};\\
\fill [nmndcolor] (0,.25ex) circle (1ex); & \node{Network Management and Network Defense Experience};\\
\fill [nmescolor] (0,.25ex) circle (1ex); & \node{Network Management and Enterprise Services Experience};\\
\fill [citscolor] (0,.25ex) circle (1ex); & \node{CITS Information Transport Systems Experience};\\
};
\end{scope}
\end{tikzpicture}

\end{document}


## 5. A word of caution

All the above is an ugly hack, and modifies macros internally used by tikz, so it will probably break with a newer version of the library. My code was tested with the version which comes with Texlive 2012 (which apparently is v 1.9 2009/11/12 of the file tikzlibrarymindmap.code.tex).

-
Hooray for "ugly hacks"! –  Loop Space Nov 28 '12 at 8:49
Impressive! Looks really good. Congratulations! –  Stephan Lehmke Nov 28 '12 at 9:26