bordertikz-pgf
I want to draw a thick border for a shape (let's say a square) inside it and not on its center, like shown in the image. I am interested in obtaining the second case.
Unfortunately I cannot find any information regarding this. I would really appreciate if someone could help me with this. Thank you in advance.
The shape is drawn with the \filldraw command
\filldraw[fill=white, draw=yellow, line width=3mm] (0, 0) rectangle +(2, 2);
Some ideas, lots of hardcoded magic numbers (found by trial and error):
\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{backgrounds, calc, shadows, shadows.blur}
\newcommand\addcurlyshadow[2][]{
% #1: Optional aditional tikz options
% #2: Name of the node to "decorate"
\begin{pgfonlayer}{background}
\path[
rounded corners=1pt,
blur shadow={shadow xshift=0pt,
shadow yshift=-0.3pt,
shadow blur steps=6,
shadow blur radius=.6pt}, #1]
($(#2.north west)+( 0.3pt,0)$) --
($(#2.south west)+( 0.3pt,0)$) --
($(#2.south east)+(-0.3pt,0)$) --
($(#2.north east)+(-0.3pt,0)$) --
cycle;
\path[rounded corners,
blur shadow={shadow xshift=0pt,
shadow yshift=0pt,
shadow blur steps=8,
shadow blur radius=2pt}, #1]
($(#2.north west)+(-1pt,-2pt)$) --
($(#2.south west)+(-1pt, 2pt)$) --
($(#2.south east)+( 1pt, 2pt)$) --
($(#2.north east)+( 1pt,-2pt)$) --
cycle;
\end{pgfonlayer}
}
\begin{document}
\begin{tikzpicture}
\begin{pgfonlayer}{background}
\fill[black!20] (-3,-1) rectangle (3,1);
\end{pgfonlayer}
\node[fill=white, rectangle, minimum width=3cm, minimum height=1cm]
(example) {Test};
\addcurlyshadow{example}
\end{tikzpicture}
\end{document}
Result:
Here's what I came up with. I basically used the example from the PGF manual and tried to emulate the rectangle shape as much as possible.
The shape is defined by the macro \myshapepath. All anchor points are calculated using the intersection library, so they should be exact. Defining the shape so it looks good at different aspect ratios is kind of difficult, though.
\documentclass{standalone}
\usepackage{tikz}
\usetikzlibrary{intersections}
\makeatletter
\def\myslant{0.2} % defines the skew of the right and left side
\def\myxsep{0.5} % extra distance in x direction; relative to node height
\def\myvhandlelen{.85} % length of the vertical bezier handles; relative to node height
\def\myhhandlelen{.65} % length of the horizontal bezier handles; relative to node width
\def\mypoint#1#2#3{
% #1 = x coordinate, in multiples of the width
% #2 = y coordinate, in multiples of the height, slanted
% #3 = x coordinate, relative to height and slant factor
\pgfpointdiff{\southwest}{\northeast}
\pgf@xc=\pgf@x % xc = width of the node
\pgf@yc=\pgf@y % yc = height of the node
\pgf@xb=\myslant\pgf@yc % xb = width of the node scaled by \myslant
\southwest
\advance\pgf@x by .5\pgf@xc
\advance\pgf@y by .5\pgf@yc
\advance\pgf@x by #1\pgf@xc
\advance\pgf@y by #2\pgf@yc
\advance\pgf@x by #2\pgf@xb
\advance\pgf@x by #3\pgf@xb
}
% this defines the shape of the node; the macro is used for drawing the shape as well as for calculating intersection points
\def\myshapepath{
\pgfpathmoveto{\mypoint{-.5}{0}{-\myxsep}}
\pgfpathcurveto{\mypoint{-.5}{\myvhandlelen}{-\myxsep}}{\mypoint{-\myhhandlelen}{.5}{0}}{\mypoint{0}{.5}{0}}
\pgfpathcurveto{\mypoint{\myhhandlelen}{.5}{0}}{\mypoint{.5}{\myvhandlelen}{\myxsep}}{\mypoint{.5}{0}{\myxsep}}
\pgfpathcurveto{\mypoint{.5}{-\myvhandlelen}{\myxsep}}{\mypoint{\myhhandlelen}{-.5}{0}}{\mypoint{0}{-.5}{0}}
\pgfpathcurveto{\mypoint{-\myhhandlelen}{-.5}{0}}{\mypoint{-.5}{-\myvhandlelen}{-\myxsep}}{\mypoint{-.5}{0}{-\myxsep}}
\pgfpathclose
}
% compute an intersection point between a line and \myshapepath
\def\myshapeanchorborder#1#2{
% #1 = point inside the shape
% #2 = direction
\pgftransformreset % without this, the intersection commands yield strange results
\pgf@relevantforpicturesizefalse % don't include drawings in bounding box
\pgfintersectionofpaths{
\myshapepath
%\pgfgetpath\temppath\pgfusepath{stroke}\pgfsetpath\temppath % draw path for debugging
}{
\pgfpathmoveto{
\pgfpointadd{
\pgfpointdiff{\southwest}{\northeast}\pgf@xc=\pgf@x \advance\pgf@xc by \pgf@y % calculate a distance that is guaranteed to be outside the shape
\pgfpointscale{
\pgf@xc
}{
\pgfpointnormalised{
#2
}
}
} {
#1
}
}
\pgfpathlineto{#1}
%\pgfgetpath\temppath\pgfusepath{stroke}\pgfsetpath\temppath % draw path for debugging
}
\pgfpointintersectionsolution{1}
}
\def\myshapeanchorcenter{
\pgfpointscale{.5}{\pgfpointadd{\southwest}{\northeast}}
}
% we could probably re-use some existing \dimen, but better be careful
\newdimen\myshapedimenx
\newdimen\myshapedimeny
\pgfdeclareshape{myshape}{
% some stuff, we can inherit from the rectangle shape
\inheritsavedanchors[from=rectangle]
\inheritanchor[from=rectangle]{center}
\inheritanchor[from=rectangle]{mid}
\inheritanchor[from=rectangle]{base}
% calculate these anchors so they lie on a coorinate line with .center
\anchor{west}{\myshapeanchorborder{\myshapeanchorcenter}{\pgfpoint{-1cm}{0cm}}}
\anchor{east}{\myshapeanchorborder{\myshapeanchorcenter}{\pgfpoint{1cm}{0cm}}}
\anchor{north}{\myshapeanchorborder{\myshapeanchorcenter}{\pgfpoint{0cm}{1cm}}}
\anchor{south}{\myshapeanchorborder{\myshapeanchorcenter}{\pgfpoint{0cm}{-1cm}}}
% calculate these anchors so they lie on a line through .center and the corresponding anchor of the underlying rectangle
\anchor{south west}{\myshapeanchorborder{\myshapeanchorcenter}{\pgfpointdiff{\myshapeanchorcenter}{\southwest}}}
\anchor{north east}{\myshapeanchorborder{\myshapeanchorcenter}{\pgfpointdiff{\myshapeanchorcenter}{\northeast}}}
\anchor{south east}{\myshapeanchorborder{\myshapeanchorcenter}{\pgfpointdiff{\myshapeanchorcenter}{\northeast\pgf@xa=\pgf@x\southwest\pgf@x=\pgf@xa}}}
\anchor{north west}{\myshapeanchorborder{\myshapeanchorcenter}{\pgfpointdiff{\myshapeanchorcenter}{\southwest\pgf@xa=\pgf@x\northeast\pgf@x=\pgf@xa}}}
% somewhat more special anchors. The coordinate calculations were taken from the rectangle node
\anchor{mid west}{\myshapeanchorborder{\myshapeanchorcenter\pgfmathsetlength\pgf@y{.5ex}}{\pgfpoint{-1cm}{0cm}}}
\anchor{mid east}{\myshapeanchorborder{\myshapeanchorcenter\pgfmathsetlength\pgf@y{.5ex}}{\pgfpoint{1cm}{0cm}}}
\anchor{base west}{\myshapeanchorborder{\myshapeanchorcenter\pgf@y=0pt}{\pgfpoint{-1cm}{0cm}}}
\anchor{base east}{\myshapeanchorborder{\myshapeanchorcenter\pgf@y=0pt}{\pgfpoint{1cm}{0cm}}}
\backgroundpath{
% uncomment to draw underlying rectangle node
%\southwest\pgf@xa=\pgf@x \pgf@ya=\pgf@y
%\northeast\pgf@xb=\pgf@x \pgf@yb=\pgf@y
%\pgfpointdiff{\southwest}{\northeast}\pgf@xc=\pgf@x \pgf@yc=\pgf@y
%\pgfpathmoveto{\pgfpoint{\pgf@xa}{\pgf@ya}}
%\pgfpathlineto{\pgfpoint{\pgf@xa}{\pgf@yb}}
%\pgfpathlineto{\pgfpoint{\pgf@xb}{\pgf@yb}}
%\pgfpathlineto{\pgfpoint{\pgf@xb}{\pgf@ya}}
%\pgfpathclose
\myshapepath
}
\anchorborder{
\myshapedimenx=\pgf@x
\myshapedimeny=\pgf@y
\myshapeanchorborder{\myshapeanchorcenter}{\pgfpoint{\myshapedimenx}{\myshapedimeny}}
}
}
\makeatother
\tikzset{shape example/.style={color=black!30,draw,fill=yellow!30,line width=.5cm,inner xsep=2.5cm,inner ysep=0.5cm}}
\begin{document}
{\Huge\begin{tikzpicture}
\node[name=s,shape=myshape,shape example] {myshape\vrule width 1pt height 2cm};
\foreach \anchor/\placement in {
north west/above left,
north/above,
north east/above right,
west/left,
center/above,
east/right,
mid west/right,
mid/above,
mid east/left,
base west/left,
base/below,
base east/right,
south west/below left,
south/below,
south east/below right,
text/left,
10/right,
130/above%
} {
\draw[shift=(s.\anchor)] plot[mark=x] coordinates{(0,0)}
node[\placement] {\scriptsize\texttt{(s.\anchor)}};
}
\end{tikzpicture}}
\begin{tikzpicture}
\draw (-2.0, 0.0) node[draw,myshape] (a) {normal};
\draw (-0.5, 2.0) node[draw,myshape] (b) {very long node indeed};
\draw ( 2.0, 0.0) node[draw,myshape,align=left] (c) {h\\i\\g\\h\\\\n\\o\\d\\e};
\draw ( 0.0,-1.5) node[draw,myshape,align=left] (d) {almost\\square\\node};
\draw[->] (a) -> (b);
\draw[->] (b) -> (c);
\draw[->] (c) -> (d);
\draw[->] (d) -> (a);
\end{tikzpicture}
\end{document}
The big advantage is that you have full control over the node shape, however it has to be specified in PGF with none of the fancy TikZ syntax. It's quite a lot of code, though, maybe there is an easier way...
Best Answer
you can clip the half of it and then force it to draw it again double the line width. The scope limits the clipping effect.
or using Mark Wibrow's further shortcut makes it a one-liner