I would like to draw a rectangle along the border of a circle. The \draw with the \angle operation might do it, but it is rather cumbersome.
I was wondering if there is another more elegant/shorter solution, i.e. a command that draws shapes along other shapes.
Ok sorry for the late update. What I want to do is more something along the following:
A (badly) drawn rectangle following the border of a circle.
Below is a macro that draws the desired shape around the circle:
\DrawAlong{(Center)}{\Radius}{\Separation}{120}{60}
yields the blue shape from 120 to 60 degrees, and
\DrawAlong[draw=black,fill=yellow, fill opacity=0.4]{(Center)}{\Radius}{\Separation}{-30}{-60}
yields the filled in yellow shape from -30 to -60 degrees:
\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{calc}
\newdimen\XCoord%
\newdimen\YCoord%
\makeatletter
\newlength{\My@OuterArcRadius}
\newlength{\My@InnerArcRadius}
\newlength{\My@OuterXStart}
\newlength{\My@OuterYStart}
\newlength{\My@OuterXEnd}
\newlength{\My@OuterYEnd}
\newlength{\My@InnerXStart}
\newlength{\My@InnerYStart}
\newlength{\My@InnerXEnd}
\newlength{\My@InnerYEnd}
%
\newcommand*{\DrawAlong}[6][]{%
% [#1] = style (optional)
% {#2} = center
% {#3} = radius
% {#4} = separation
% {#5} = arch angle start
% {#6} = arc angle end
\def\My@center{#2}%
\def\My@radius{#3}%
\def\My@separation{#4}%
\def\My@arcStart{#5}%
\def\My@arcEnd{#6}%
%
\pgfmathsetlength{\My@OuterArcRadius}{\My@radius+\My@separation}
\pgfmathsetlength{\My@InnerArcRadius}{\My@radius-\My@separation}
%
% Extract coordinates of center: (XCoord,YCoord)
% https://tex.stackexchange.com/questions/33703/extract-x-y-coordinate-of-an-arbitrary-point-in-tikz/33706#33706
\path \My@center; \pgfgetlastxy{\XCoord}{\YCoord}
%
\pgfmathsetlength{\My@OuterXStart}{\XCoord+(\My@OuterArcRadius*cos(\My@arcStart))}
\pgfmathsetlength{\My@OuterYStart}{\YCoord+(\My@OuterArcRadius*sin(\My@arcStart))}
\pgfmathsetlength{\My@OuterXEnd}{\XCoord+(\My@OuterArcRadius*cos(\My@arcEnd))}
\pgfmathsetlength{\My@OuterYEnd}{(\YCoord+\My@OuterArcRadius*sin(\My@arcEnd))}
%
\pgfmathsetlength{\My@InnerXStart}{\XCoord+(\My@InnerArcRadius*cos(\My@arcStart))}
\pgfmathsetlength{\My@InnerYStart}{\YCoord+(\My@InnerArcRadius*sin(\My@arcStart))}
\pgfmathsetlength{\My@InnerXEnd}{(\XCoord+\My@InnerArcRadius*cos(\My@arcEnd))}
\pgfmathsetlength{\My@InnerYEnd}{(\YCoord+\My@InnerArcRadius*sin(\My@arcEnd))}
%
\draw [ultra thick, blue,#1]
(\My@OuterXStart,\My@OuterYStart)
arc (\My@arcStart:\My@arcEnd:\My@OuterArcRadius)
-- (\My@InnerXEnd, \My@InnerYEnd)
arc (\My@arcEnd:\My@arcStart:\My@InnerArcRadius)
--cycle;
}%
\makeatother
\begin{document}
\newcommand*{\Radius}{2cm}%
\newcommand*{\Separation}{0.2cm}%
%
\begin{tikzpicture}[ultra thick]
\coordinate (Center) (1cm,3cm);
\DrawAlong{(Center)}{\Radius}{\Separation}{120}{60}
\DrawAlong[draw=black,fill=yellow, fill opacity=0.4]{(Center)}{\Radius}{\Separation}{-30}{-60}
\draw [red ] (Center) circle (\Radius);
\end{tikzpicture}
\end{document}
If you know the radius of the circle, you can simple coordinate calculations to draw the rectangle. The circle radius is specified in \Radius and \Separation defines the separation you want between the circle and rectangle:
Alternatively, you could define a custom shape that has a rectangle around the circle, then simply using it as a node shape you would obtain the desired results:
\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{calc}
\newcommand*{\Radius}{2cm}%
\newcommand*{\Separation}{2pt}%
\begin{document}
\begin{tikzpicture}[ultra thick]
\coordinate (Center) (1cm,3cm);
\draw [red ] (Center) circle (\Radius);
\draw [blue] ($(Center)-(\Radius,\Radius)-(\Separation,\Separation)$) rectangle (\Radius+\Separation,\Radius+\Separation);
\end{tikzpicture}
\end{document}
This is a modified version from How to draw inside a TikZ node, using node style?
\documentclass{article}
\usepackage{tikz}
\makeatletter
\pgfdeclareshape{CircleRectangle}
%
% Rectangle with an inscribed circle. Based on 'circle' shape
%
{%
% All anchors are taken from the 'circle' shape:
\inheritsavedanchors[from={circle}]%
\inheritanchor[from={circle}]{center}%
\inheritanchor[from={circle}]{mid}%
\inheritanchor[from={circle}]{base}%
\inheritanchor[from={circle}]{north}%
\inheritanchor[from={circle}]{south}%
\inheritanchor[from={circle}]{west}%
\inheritanchor[from={circle}]{east}%
\inheritanchor[from={circle}]{mid west}%
\inheritanchor[from={circle}]{mid east}%
\inheritanchor[from={circle}]{base west}%
\inheritanchor[from={circle}]{base east}%
\inheritanchor[from={circle}]{north west}%
\inheritanchor[from={circle}]{south west}%
\inheritanchor[from={circle}]{north east}%
\inheritanchor[from={circle}]{south east}%
\inheritanchorborder[from={circle}]%
%
% Only the background path is different
%
\backgroundpath{%
% First the existing 'circle' code:
\pgfutil@tempdima=\radius%
\pgfmathsetlength{\pgf@xb}{\pgfkeysvalueof{/pgf/outer xsep}}%
\pgfmathsetlength{\pgf@yb}{\pgfkeysvalueof{/pgf/outer ysep}}%
\ifdim\pgf@xb<\pgf@yb%
\advance\pgfutil@tempdima by-\pgf@yb%
\pgfutil@tempdimb=\pgfutil@tempdima%
\else%
\advance\pgfutil@tempdima by-\pgf@xb%
\pgfutil@tempdimb=\pgfutil@tempdima%
\fi%
\pgfpathcircle{\centerpoint}{\pgfutil@tempdima}%
%
% Now the outer rectangle
\pgfmoveto{\pgfpointadd{\centerpoint}{\pgfpoint{-\pgfutil@tempdima}{-\pgfutil@tempdima}}}%
\pgflineto{\pgfpointadd{\centerpoint}{\pgfpoint{\pgfutil@tempdima}{-\pgfutil@tempdima}}}%
\pgflineto{\pgfpointadd{\centerpoint}{\pgfpoint{\pgfutil@tempdima}{\pgfutil@tempdima}}}%
\pgflineto{\pgfpointadd{\centerpoint}{\pgfpoint{-\pgfutil@tempdima}{\pgfutil@tempdima}}}%
\pgflineto{\pgfpointadd{\centerpoint}{\pgfpoint{-\pgfutil@tempdima}{-\pgfutil@tempdima}}}%
}%
}
\makeatother
\begin{document}
\begin{tikzpicture}
\node [draw=blue, CircleRectangle, inner sep=1pt] at (2,0) {text};
\end{tikzpicture}
\end{document}
You could use the fit library to make a rectangle node sourround a circle. by setting inner sep and outer sep to 0pt you can control the size of the circle with minimum size=xx.
\documentclass{minimal}
\usepackage{tikz}
\tikzset{%
no sep/.style={inner sep=0pt, outer sep=0pt}
}
\usetikzlibrary{fit}
\begin{document}
\begin{tikzpicture}
\node (your circle) at (2,1) [no sep, draw, shape=circle, minimum size=1cm] {};
\node [draw, no sep, fit={(your circle)}] {};
\end{tikzpicture}
\end{document}
minimal class and instead use article as the minimal class.
shapes library with regular polygon option. See the example in the manual.
minimal class" Why should the minimal class be avoided?. This is mostly for me in case I come back here and think I said I was going to do something and then flaked. :-)