[Tex/LaTex] Why does a tikz spy specified as a chamfered rectangle show up as a simple rectangle

spytikz-pgf

I'd like to use a tikz spy shaped like a chamfered rectangle.
The code runs without complaining, but the result is a plain rectangle.
"rounded rectangle" works as expected, as does chamfered-rectangle-shaped non-spy nodes. How could I fix this?

The code below should demonstrate my problem. Unfortunately I don't have enough rep to add a picture..

pdflatex Version 3.1415926-2.4-1.40.13 (TeX Live 2012/Debian)
I had the same issue in Windows yesterday, I believe that was Tex Live 2012 as well.
tikz 2010/10/13 v2.10 (rcs-revision 1.76)

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{spy,decorations.fractals,shapes.misc}

\begin{document}

\tikz\node[draw, circle] {circle};
\begin{tikzpicture}
  [spy using outlines={circle, magnification=3, size=1cm, connect spies}]
  \draw [decoration=Koch curve type 1]
    decorate{ decorate{ decorate{ (0,0) -- (2,0) }}};
  \spy [red] on (1.6,0.3) in node at (3,1);
\end{tikzpicture}

\tikz\node[draw, rounded rectangle] {rounded rectangle};
\begin{tikzpicture}
  [spy using outlines={rounded rectangle, magnification=3, width=2cm, height=1cm, connect spies}]
  \draw [decoration=Koch curve type 1]
    decorate{ decorate{ decorate{ (0,0) -- (2,0) }}};
  \spy [red] on (1.6,0.3) in node at (3,1);
\end{tikzpicture}

\tikz\node[draw, chamfered rectangle] {chamfered rectangle};
\begin{tikzpicture}
  [spy using outlines={chamfered rectangle, magnification=3, width=2cm, height=1cm, connect spies}]
  \draw [decoration=Koch curve type 1]
    decorate{ decorate{ decorate{ (0,0) -- (2,0) }}};
  \spy [red] on (1.6,0.3) in node at (3,1);
\end{tikzpicture}

\end{document}

Here's what it produces for me:

enter image description here

Best Answer

The chamfered rectangle shape uses the height, depth and width of the node’s text box as well as the inner separator to compute its path (as every other shape).

This can be simulated with a normal node with inner sep set to zero (the spy nodes use this too):

\tikz
  \node[draw, chamfered rectangle, minimum width=2cm, minimum height=1cm, inner sep=0pt] {};

So, the next idea would be to include an inner sep again in the every spy on node as well as the every spy in node.

My other solution provides a specific fix for the chamfered rectangle which will use the minimum height and minimum width as a replacement for the text box.

The yellow box shows in both solutions where the 2cm × 1cm will be measured.

Code A (`inner sep`)

\documentclass[tikz,convert=false]{standalone}
\usetikzlibrary{spy,decorations.fractals,shapes.misc}
\begin{document}
\begin{tikzpicture}[
  spy using outlines={
    shape=chamfered rectangle,
    every spy on node/.append style={inner sep=+.3333em},
    every spy in node/.append style={inner sep=+.3333em},
    magnification=3,
    width=2cm,
    height=1cm,
    connect spies
  }]
  \draw [decoration=Koch curve type 1]
    decorate{ decorate{ decorate{ (0,0) -- (2,0) }}};
  \spy[red] on (1.6,0.3) in node at (3,1);
  \node[draw=green, thick, minimum width=2cm/3, minimum height=1cm/3] at (1.6,.3) {};
\end{tikzpicture}
\end{document}

Code B (specific fix)

\documentclass[tikz,convert=false]{standalone}
\usepackage{etoolbox}
\usetikzlibrary{spy,decorations.fractals,shapes.misc}
\makeatletter
\newif\iftikz@lib@spy@active
\expandafter\patchcmd\csname pgfk@/tikz/spy scope/.@cmd\endcsname
  {\copy\tikz@lib@spybox\tikz@lib@spy@collection}
  {\copy\tikz@lib@spybox\tikz@lib@spy@activetrue\tikz@lib@spy@collection}{}{}
\expandafter\patchcmd\csname pgf@sh@s@chamfered rectangle\endcsname{%
  \pgfmathsetlength\pgf@xa{\pgfkeysvalueof{/pgf/inner xsep}}%
  \advance\pgf@xa.5\wd\pgfnodeparttextbox%
  \pgfmathsetlength\pgf@ya{\pgfkeysvalueof{/pgf/inner ysep}}%
  \advance\pgf@ya.5\ht\pgfnodeparttextbox%
  \advance\pgf@ya.5\dp\pgfnodeparttextbox%
}{%
  \pgfmathsetlength\pgf@xa{\pgfkeysvalueof{/pgf/inner xsep}}%
  \pgfmathsetlength\pgf@ya{\pgfkeysvalueof{/pgf/inner ysep}}%
  \iftikz@lib@spy@active
    \pgfmathaddtolength\pgf@xa{.5*(\pgfkeysvalueof{/pgf/minimum width}-2*(\pgfkeysvalueof{/pgf/chamfered rectangle xsep}))}%
    \pgfmathaddtolength\pgf@ya{.5*(\pgfkeysvalueof{/pgf/minimum height}-2*(\pgfkeysvalueof{/pgf/chamfered rectangle ysep}))}%
  \else
    \advance\pgf@xa.5\wd\pgfnodeparttextbox%
    \advance\pgf@ya.5\ht\pgfnodeparttextbox%
    \advance\pgf@ya.5\dp\pgfnodeparttextbox%
  \fi}{}{}
\makeatother
\begin{document}
\begin{tikzpicture}[
  spy using outlines={
    shape=chamfered rectangle,
    magnification=3,
    width=2cm,
    height=1cm,
    connect spies
  }]
  \draw [decoration=Koch curve type 1]
    decorate{ decorate{ decorate{ (0,0) -- (2,0) }}};
  \spy[red] on (1.6,0.3) in node at (3,1);
  \node[draw=green, thick, minimum width=2cm/3, minimum height=1cm/3] at (1.6,.3) {};
\end{tikzpicture}
\end{document}

Output (both)

enter image description here

Related Solutions

[Tex/LaTex] Rotate a node but not its content: the case of the ellipse decoration

The source of the difficulty is that ellipses are constructed in a particular way in TikZ. They are paths that start from the x-axis and proceed counter-clockwise around their centre. The vast majority of the time, the exact parametrisation doesn't matter. You appear to have found the one situation where it does!

In the actual question, you only want to be able to mirror the ellipse, and so draw it starting from the negative x-axis (the title of the question suggests a more flexible approach). That's actually not too hard since we can exploit the symmetry of the ellipse. The key is to provide it with a negative x-radius, since then it will start from the negative x-axis (and proceed clockwise, but we could correct for that by negating the y-radius as well). To do this, we interrupt the call from the node shape to the drawing command and flip the sign of the x-radius. The simplest way to do this is to redefine the \pgfpathellipse macro to do the negation and then call the original macro. The following code does this.

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{decorations,shapes,decorations.markings}
\makeatletter
\let\origpgfpathellipse=\pgfpathellipse
\def\revpgfpathellipse#1#2#3{%
  #2%
  \pgf@xa=-\pgf@x
  \origpgfpathellipse{#1}{\pgfqpoint{\pgf@xa}{0pt}}{#3}}
\makeatother

\tikzset{
  reversed ellipse/.style={
    ellipse,
    reverse the ellipse%
  },
  reverse the ellipse/.code={
    \let\pgfpathellipse=\revpgfpathellipse
  }
}
\begin{document}
\begin{tikzpicture}
\node[ellipse,
  draw,
  postaction={
    decorate,
    decoration={
      markings,
      mark=at position 1 with {
        \arrow[line width=5pt,blue]{>}
      }
    }
  }
] at (0,0) {hello world};

\node[reversed ellipse,
  draw,
  postaction={
    decorate,
    decoration={
      markings,
      mark=at position 1 with {
        \arrow[line width=5pt,blue]{>}
      }
    }
  }
] at (0,-2) {hello world};
\end{tikzpicture}

\end{document}

Here's the result:

rotated ellipse

(the arrow got clipped, but you can see where it lies)

[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

Code A (inner sep)

Code B (specific fix)

Output (both)

Related Solutions

[Tex/LaTex] Rotate a node but not its content: the case of the ellipse decoration

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

Related Question

Code A (`inner sep`)