[Tex/LaTex] No content in zoom Tikz spy

spytikz-pgf

I'm trying to use the spy glass in Tikz, but for some reason my zoom area is always empty and (some) graphs tend to disappear when I use spy. I've updated all my packages etc. through the updater by MikTeX but this didn't solve anything. The code I use:

\documentclass{article} 
\usepackage{pgfplots} 
\usetikzlibrary{spy} 

\begin{document}  
\begin{tikzpicture}
[spy using outlines={rectangle, magnification=3,connect spies}] 

\begin{axis}[grid=major,no markers,domain=-5:5,enlargelimits=false] 
    \addplot[solid,mark=asterisk,mark options={solid},color=blue] {x^2};
    \addplot[solid,mark=asterisk,mark options={solid},color=red] {x^3};  
    \addplot[only marks,mark=star,mark size=2pt,color=black] coordinates{(0,0)};
    \coordinate (spypoint) at (axis cs:0,0); 
    \coordinate (spyviewer) at (axis cs:0.5,-90); 
\end{axis}  
    \spy[width=6cm,height=1cm] on (spypoint) in node [fill=white] at (spyviewer); 

\end{tikzpicture}  

\begin{tikzpicture}
%[spy using outlines={rectangle, magnification=3,connect spies}] 

\begin{axis}[grid=major,no markers,domain=-5:5,enlargelimits=false] 
    \addplot[solid,mark=asterisk,mark options={solid},color=blue] {x^2};
    \addplot[solid,mark=asterisk,mark options={solid},color=red] {x^3};  
    \addplot[only marks,mark=star,mark size=2pt,color=black] coordinates{(0,0)};
    %\coordinate (spypoint) at (axis cs:0,0); 
    %\coordinate (spyviewer) at (axis cs:0.5,-90); 
\end{axis}  
    %\spy[width=6cm,height=1cm] on (spypoint) in node [fill=white] at (spyviewer); 

\end{tikzpicture}  
\end{document}

I'm not allowed to upload an image here since I'm new, but the red and blue graphs disappear with the spy glass, where the black dot remains. The areas of the spy glass are correct, but also the black dot doesn't appear in the zoom area, it's completely empty. When not using spy, the graphs appear perfectly fine…

Best Answer

Ok, that was enough info to sort of track down what is going on. There was a bug in the spy library that caused it to fail with dvips or xelatex. This was reported and apparently fixed here, but I don't think there's actually been a release of pgf/tikz since then, at least not one that is showing up on sourceforge, so updating the tex installation wouldn't help.

You could try subbing in the newest version of this library to your pgf installation (source code here). However I tried doing this and it didn't quite work, though it behaved differently than the buggy behavior (which, incidentally, I was able to replicate) -- the spy part worked but the plot part didn't. Possibly I was doing something wrong and I didn't try very hard. But probably you would need to install the development version of the whole package to fix this bug in the meantime, rather than just updating this one file. Or give up on .ps as you say :).

Related Solutions

[Tex/LaTex] Scalebar Overlay and TikZ spy

I used a different approach to get the desired result. Instead of spy library, I create two nodes: one for the image, other for the zoomed detail. I include the same image in both, but I clip the second one to the appropiate rectangle, and then use \scalebox to make it bigger. You can also draw lines connecting both nodes (original image and zoomed details).

Since the factor applied to \scalebox is known, it is easy to determine also the dimensions of the "zoomed" scalebar.

I passed as parameters also the corners of the rectangle to be zoomed. Note however that I defined x and y with the same value, so that the helping grid has square cells. This means that, the image coordinate system goes from 0 to 1 for x axis, but not for y axis (unless the image is square itself).

This is my code:

\documentclass{article}

\usepackage{graphicx}
\usepackage{tikz}
\usetikzlibrary{positioning}

\newcommand\scalebarandzoom[8][white]{ 
% #1 = color of bar
% #2 = image size
% #3 = image
% #4 = lower left corner of viewport
% #5 = upper right corner of viewport
% #6 = magnification factor
% #7 = actual size of the image in some units
% #8 = actual size of the scalebar in the same units than #7
\begin{tikzpicture}[x=#2, y=#2, font=\footnotesize]
  \node[anchor=south west,inner sep=0] (image) at (0,0) {\includegraphics[width=#2]{#3}};
  % \draw[help lines,xstep=.1,ystep=.1] (0,0) grid (1,1);
  % \foreach \x in {0,1,...,9} { \node [anchor=north] at (0.\x,0) {.\x}; }
  % \foreach \y in {0,1,...,9} { \node [anchor=east] at (0,0.\y) {.\y}; }
  \coordinate (viewport lower left) at (#4);
  \coordinate (viewport upper right) at (#5);
  \draw[red] (viewport lower left) rectangle (viewport upper right);
  \node[right=of image, draw=red, inner sep=1pt] (zoom) {%
       \scalebox{#6}{\tikz{
          \clip (#4) rectangle (#5);
          \node[anchor=south west,inner sep=0] at (0,0) {\includegraphics[width=#2]{#3}};
         }}%
       };
  % Help lines
  \draw[red, dashed] (viewport lower left|-viewport upper right) -- (zoom.north west);
  \draw[red, dashed] (viewport lower left) -- (zoom.south west);
  % Scalebars
  \fill [#1] (image.south east) ++(-2mm,2mm) ++(-#8/#7,    0mm) rectangle ++(#8/#7,   1.5mm);
  \fill [#1] (zoom.south east)  ++(-2mm,2mm) ++(-#8/#7*#6, 0mm) rectangle ++(#8/#7*#6,1.5mm);
\end{tikzpicture}
}

\begin{document}
\scalebarandzoom[orange]{6cm}{cheek.png}{0.52, 0.23}{0.68,0.35}{3}{500}{50}
\end{document}

And this is the result:

Result

(image cheek.png can be found here)

[Tex/LaTex] TikZ: using the spy library to zoom in

The second question seems easy to solve. You can use spy using outlines=circle, you can use \spy [circle …] ….

The solution to first question depends on what you want to do exactly.

Usually we can use a path picture that implement a rectangular shape the size of the path. The advantage of a path picture against naming the node and referencing it later (which I also have done in the code below) is that it is being clipped against the node’s shape path and also will lie in the background.

The problem here is, that the spy mechanism is implemented via a path picture itself. Any other extra path picture will overwrite any previous given path picture or will be overwritten by any following path picture (i.e. the one that does the spying).

Without any warranties, the solution below includes an additional path picture extra key that simply sets a macro that is hard-coded in the default path picture. Please notice that any path inside the path picture inherits the styles from the spy on node itself.

You cannot however, reference anything from the original picture as this has been saved in a (TeX) box and is simply transformed into the spy on node.

Code

\documentclass[tikz,convert=false]{standalone}
\usetikzlibrary{calc}
\usetikzlibrary{spy}
\usetikzlibrary{intersections}
\makeatletter
\tikzset{
  path picture/.code=\tikz@addmode{\def\tikz@path@picture{#1\tikz@path@picture@extra}},
  path picture extra/.code={\def\tikz@path@picture@extra{#1}}
}
\let\tikz@path@picture@extra\pgfutil@empty
\makeatother
\begin{document}
\begin{tikzpicture}
  \begin{scope}[spy using outlines]
  \coordinate (F) at (2, 0);

  \draw[name path = line] (F) -- ++(30:1cm and 2cm) coordinate (A);
  \draw (F) -- ++(100:1cm) coordinate (P3);

  \draw[name path = arc] let
      \p0 = (F),
      \p1 = (A),
      \p2 = (P3),
      \n1 = {atan2(\x1 - \x0, \y1 - \y0)},
      \n2 = {atan2(\x2 - \x0, \y2 - \y0)},
      \n3 = {1cm},
      \n4 = {(\n2 + \n1) / 2}
    in (F) +(\n1:\n3) arc[radius = \n3, start angle = \n1, end angle = \n2]
    node[font = \scriptsize, fill = white, inner sep = 0cm] at
    ([shift = (F)] \n4:\n3) {\(\nu_A\)} coordinate (N);

    \path[name intersections = {of = line and arc, by = B}];
    \spy [blue, circle, draw, height = .5cm, width = .5cm, magnification = 2, connect spies,
      path picture extra={
        \draw (path picture bounding box.north west) -- (path picture bounding box.south east);
        \draw[help lines, step=.1cm] (path picture bounding box.south west) grid (path picture bounding box.north east);
      }] on ($(F)!.5!(B)$) in node (s) at ($(F)!.5!(B) + (0, -1)$);
 \end{scope}
 \draw([shift=(left:.25)]s.west) arc [radius=.5, start angle=180, end angle=0];
\end{tikzpicture}
\end{document}

Output

enter image description here