[Tex/LaTex] How to compute rotated bounding boxes

tikz-pgf

Edit: As suggested by percusse's answer, I can use transform shape option. My first question is now solved. But although the second bounding box is now locally aligned, it is not correct. In fact, local bounding box always computes a globally aligned bounding box (green points) and fit encloses north, east,south, and west anchors of this bounding box.

My question is now: how to compute a local bounding box locally aligned?

New example (the blue rectangle on the right does not fit the red path):

\documentclass{standalone}
\usepackage{tikz}
\usetikzlibrary{fit}
\tikzset{
  pt/.style={circle,minimum size=3pt,fill=#1,inner sep=0},
  red pt/.style={pt=red},
  green pt/.style={pt=green},
  every picture/.style={line width=1pt,inner sep=0pt},
}
\begin{document}
\begin{tikzpicture}[rotate=20]
  \draw[gray,line width=.4pt] (0,0) grid (6.5,2.5);
  % first case: fitting some nodes
  \node[red pt] (a) at (.5,.5){};
  \node[red pt] (b) at (.5,2){};
  \node[red pt] (c) at (3,.5){};
  \node[red pt] (d) at (2,2.2){};
  \begin{scope}[transform shape]
    \node[fit=(a)(b)(c)(d),draw=blue]{};
  \end{scope}

  % second case: fitting arbitrary path
  \begin{scope}[local bounding box=bb]
    \draw[red] (4,1) to[bend right] (6,1) -- (5,2);
  \end{scope}
  \node[green pt] at (bb.north west){};
  \node[green pt] at (bb.north east){};
  \node[green pt] at (bb.south west){};
  \node[green pt] at (bb.south east){};
  % how to find correct bounding box locally aligned ?
  \begin{scope}[transform shape]
    \node[fit=(bb),draw=blue]{};
  \end{scope}
\end{tikzpicture}
\end{document}

enter image description here

Original question:

I want to compute some bounding boxes. Here is my two cases:

to fit some nodes (or coordinates), I can use fit library.
to fit arbitrary paths, I can use a scope with local bounding box=bb.

The following code shows this two cases:

\documentclass{standalone}
\usepackage{tikz}
\usetikzlibrary{fit}
\tikzset{
  red pt/.style={circle,minimum size=3pt,fill=red,inner sep=0},
  every picture/.style={line width=1pt,inner sep=0pt},
}
\begin{document}
\begin{tikzpicture}
  \draw[gray,line width=.4pt] (0,0) grid (6.5,2.5);
  % first case: fitting some nodes
  \node[red pt] (a) at (.5,.5){};
  \node[red pt] (b) at (.5,2){};
  \node[red pt] (c) at (3,.5){};
  \node[red pt] (d) at (2,2.2){};
  \node[fit=(a)(b)(c)(d),draw=blue]{};

  % second case: fitting arbitrary path
  \begin{scope}[local bounding box=bb]
    \draw[red] (4,1) to[bend right] (6,1) -- (5,2);
  \end{scope}
  \node[fit=(bb),draw=blue]{};
\end{tikzpicture}

enter image description here

Now, I want to make the same things within a rotated picture!

My two questions:

In my first case (some nodes), I have to add rotate option to my fitting node (as rotate option does not rotate nodes). How to find automatically the correct value for this option (eg: the angle between current coordinate system and canvas coordinate system)?
In my second case (arbitrary paths), I can compute local bounding box but globally aligned. How to compute local bounding box locally aligned of an arbitrary path ?

Here is my attempt:

\documentclass{standalone}
\usepackage{tikz}
\usetikzlibrary{fit}
\tikzset{
  red pt/.style={circle,minimum size=3pt,fill=red,inner sep=0},
  every picture/.style={line width=1pt,inner sep=0pt},
}
\begin{document}
\begin{tikzpicture}[rotate=20]
  \draw[gray,line width=.4pt] (0,0) grid (6.5,2.5);
  % first case: fitting some nodes
  \node[red pt] (a) at (.5,.5){};
  \node[red pt] (b) at (.5,2){};
  \node[red pt] (c) at (3,.5){};
  \node[red pt] (d) at (2,2.2){};
  % how to find the good value for rotate (here 20)?
  \node[rotate=20,fit=(a)(b)(c)(d),draw=blue]{};

  % second case: fitting arbitrary path
  \begin{scope}[local bounding box=bb]
    \draw[red] (4,1) to[bend right] (6,1) -- (5,2);
  \end{scope}
  % how to find bounding box locally aligned ?
  \node[rotate=20,rotate fit=-20,fit=(bb),draw=blue]{};
\end{tikzpicture}
\end{document}

enter image description here

Best Answer

Am I missing the point? transform shape and resetting the rotation seems like a solution.

EDIT: I hope this time I got your point. If not, I would really appreciate explaining in terms of rotated rectangles and shapes, instead of local and global which are relative terminology with respect to the rotated Tikz picture environment.

\documentclass{standalone}
\usepackage{tikz}
\usetikzlibrary{fit}

\tikzset{
  pt/.style={circle,minimum size=3pt,fill=#1,inner sep=0},
  red pt/.style={pt=red},
  green pt/.style={pt=green},
  every picture/.style={line width=1pt,inner sep=0pt},
}
\begin{document}
\begin{tikzpicture}[rotate=20]
  \draw[gray,line width=.4pt] (0,0) grid (6.5,2.5);
  % first case: fitting some nodes
  \node[red pt] (a) at (.5,.5){};
  \node[red pt] (b) at (.5,2){};
  \node[red pt] (c) at (3,.5){};
  \node[red pt] (d) at (2,2.2){};
  \begin{scope}[transform shape]
    \node[fit=(a)(b)(c)(d),draw=blue]{};
  \end{scope}
\pgfgettransform{\currtrafo}     %Save the current trafo 

  % second case: fitting arbitrary path
\begin{scope}[local bounding box=bb]
\pgftransformresetnontranslations % Now there is no rotation and it doesn't know 
                                  % things are going to be rotated
\begin{scope}                     % We open a new scope and restore the outer trafo
\pgfsettransform{\currtrafo}      % inside the scope

\draw[red] (4,1) to[bend right] (6,1) -- (5,2);  % Draw anything
\end{scope}                                      % Now the trafo is reset again

\node[fit=(bb),draw=blue]{};     % Externally it doesn't know the content is
                                 % rotated or not

  \end{scope}                    % Back to original trafo.
\end{tikzpicture}
\end{document}

enter image description here

Related Solutions

[Tex/LaTex] Problem with overlay when a tikzpicture is inside another tikzpicture

A lot of users think that [nesting TikZ pictures] is a wrong practice

That'd be me, then.

This is another example of where unexpected results can occur. The overarching reason is simple: TikZ doesn't expect its environments to be nested and therefore doesn't check various assumptions when it starts and stops. In particular, tracing through the code then one sees that TikZ goes to a lot of effort to work with scopes and groupings within a tikzpicture environment. Since some information has to be extracted from within a scope - for example, bounding box information - TikZ has to "smuggle" this information out and it does that is by using globals. It is quite ingenious how it does this in such a way that the information is passed only to where TikZ wants it to be passed and not, for example, out of any further grouping.

But with the main tikzpicture environment itself, it doesn't expect nesting and so doesn't use these complicated methods. With the bounding box, for example, it knows that \pgf@picmaxx is the maximum x-value of the bounding box of the current picture and that there is only one picture involved, so it can regard it as a global variable because that makes life so much easier: every assignment to \pgf@picmaxx can be global to avoid the hassle with groups and scopes. To avoid complications, all we need to do is ensure that at the start of a tikzpicture environment then all of these globals are set to their defaults.

Let's trace the assignment of \pgf@picmaxx through your code:

\documentclass[11pt]{scrartcl}
\usepackage{tikz}    
\begin{document}

baseline\begin{tikzpicture}[baseline=(current bounding box.north west)]

At the start of a tikzpicture, it is set to: -16000.0pt

 \tikz[overlay]

Technically, it is set to -16000.0pt here as well

                \path (0,0) --  (1,1) node  {\color{blue}$\bullet$};

By the end of this command, it is set to 0.0pt, which is the maximum x-extent of that tikzpicture since it has the overlay key.

 \draw[help lines,blue!20] (0,0) grid (2,2) ;

Now, it is set to 57.00548pt which is the extent of the above command.

\end{tikzpicture}baseline%

It is still at 57.00548pt here since it is globally assigned.

% 
\begin{tikzpicture}[baseline=(current bounding box.south west)]

Now it is reset to -16000.0pt

  \draw[help lines,red!20] (0,0) grid (2,2) ;

Here, it is set to 57.00548pt

  \tikz[overlay]

At this point, we get reset to -16000.0pt as we've started a new tikzpicture.

                 \path (0,0) --  (1,1) node  {\color{red}$\bullet$};

Due to the overlay key, we get an assignment of 0.0pt here, which is in effect until the end of the picture.

\end{tikzpicture}baseline

And here it is still 0.0pt.

\end{document}

The reason that it works for scopes is that since scopes are meant to be nested, TikZ/PGF goes to great lengths to ensure that things like bounding boxes work correctly as scopes are set up and torn down. This, I think, is the answer to the most fundamental of your questions:

What is the real differences between a scope and a tikzpicture ?

To properly nest tikzpictures, one would have to look at the code for scopes and see what keys, lengths, and macros it goes to great lengths to preserve. Then do the same. This is, I guess, what you are effectively doing with your \savecurrentboundingbox and \restorecurrentboundingbox. I think that the question at the end of your answer would make a very good question in its own right. Even if, as I think, nesting TikZ pictures isn't a good idea, there are, as you point out, inevitably occasions when it is desirable. Knowing how to ensure that when one has to do it, one does it safely would be invaluable information (and, I think, it would show that one should not do this lightly so it would act as a deterrent).

[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

Related Solutions

[Tex/LaTex] Problem with overlay when a tikzpicture is inside another tikzpicture

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

Related Question