[Tex/LaTex] Calculating with different types of variables

arithmeticcounterslengthstikz-pgf

Is there any way to calculate the height of a node in a tikz pictures and to divide a length by an another length to get a counter and to round it up? If yes where could i read after the subject of calculating with different types of variables?

Here is an example:

\documentclass [a4paper] {article}  
\usepackage{calc}  
\usepackage{tikz,pgf}  
\usetikzlibary{arrows}  

%in this  case i want to do a framebox with the parameter of 1 line's length in a tikz pictures
%because i dont know how could i get the heigth of the node i try to calculate it by divide the full length of the text (what i got with the command \settototalheight from the calc package) by the length of 1 line (this is a parameter) so i got the number of lines(this is a value not a length so i cannot use the \divide command because the type of the variable)  
\newlength \widthofone \fullwidth \heightoneline \fullheight
\nemcounters \numberoflines 

\newcommand {\altframe}[2] { %#1 the text #2 the width of the lines
\widthofone=#2pt %im not sure how to convert a length from a value but i try to input the 2nd parameter into a length variable  
\settototalheight{\heightoneline}{qwe} %i get the height of one line by the calc package  
\setwidth{\totalwidth}{#1} %i calculate the width of the text    
%And now i would divide \fullwidth by \widthofone ,if i would know how to do it, to get  \numberoflines  
 %I would multiply it by \height to get \fullheight  
\begin{tikzpictures}  

   \node[text width=#2pt] at (0,0) {#1};%i write out the text  
   \draw[->,color=black] (\fullwidth/2,\fullheight/2) -- (0-\fullwidth/2,\fullheight/2); %i draw out the lines (i use height/2 becouse of the fact that the (0,0) coordinate is the middle of the picture)  
   \draw[->,color=black] (\fullwidth/2,0-\fullheight/2) -- (0-\fullwidth/2,0-\fullheight/2);  
   \draw[->,color=black] (\fullwidth/2,\fullheight/2) -- (\fullwidth/2,0-\fullheight/2);  
   \draw[->,color=black] (0-\fullwidth/2,\fullheight/2) -- (0-\fullwidth/2,0-\fullheight/2);   
\end{tikzpictures}
}

\begin{document}
\altframe{i love this sample text}{100}


\end{document}

Best Answer

I cannot figure out what are you going to do. But for your subquestions:

calculate the height of a node in a tikz pictures

Similar to \widthof within tikzpicture

\makeatletter
\newcommand\getheightofnode[2]{%
    \pgfextracty{#1}{\pgfpointanchor{#2}{north}}%
    \pgfextracty{\pgf@ya}{\pgfpointanchor{#2}{south}}%
    \addtolength{#1}{-\pgf@ya}}
\makeatother

divide a length by another length

you can \usetikzlibrary{math}, and simply write

\tikzmath{
    \numberoflines=\fullwidth/\widthofone;}

and round it up

\tikzmath{
    \numberoflines=ceil(\fullwidth/\widthofone);}

However, please notice that

  • the number of lines cannot be calculated like that. Since TeX tends to break lines at appropriate positions, the number of lines is usually larger.
  • 'the (total) height of a line' is not a constant. For example {x xx}, {M MM}, and {j jj} are of different height.
  • And still worse, 'the (total) height of a line in a paragraph' is different from what \settototalheight gives you. Usually the former is \baselineskip, but it can be larger.

So I guess the following code is closer to your approach

\documentclass{article}  
\usepackage{calc,tikz}\usetikzlibrary{math}

\newlength\widthofone \newlength\fullwidth \newlength\heightoneline \newlength\fullheight

\makeatletter
\newcommand\getheightofnode[2]{%
    \pgfextracty{#1}{\pgfpointanchor{#2}{north}}%
    \pgfextracty{\pgf@ya}{\pgfpointanchor{#2}{south}}%
    \addtolength{#1}{-\pgf@ya}}
\makeatother

\newcommand {\altframe}[2]{
\widthofone=#2
\heightoneline\baselineskip
\settowidth{\fullwidth}{#1}

\begin{tikzpicture}[->,color=black]
    \node[text width=#2](baby)at(0,0){#1};
    \getheightofnode\fullheight{baby}
    \tikzmath{
        \numberoflines=round(\fullheight/\heightoneline);}
    \draw(\fullwidth/2,\fullheight/2)--(-\fullwidth/2,\fullheight/2);
    \draw(\fullwidth/2,-\fullheight/2)--(-\fullwidth/2,-\fullheight/2);
    \draw(\fullwidth/2,\fullheight/2)--(\fullwidth/2,-\fullheight/2);
    \draw(-\fullwidth/2,\fullheight/2)--(-\fullwidth/2,-\fullheight/2);
    \node[text width=5cm]at(0,-3){
        widthofone      =\the\widthofone    \\
        fullwidth       =\the\fullwidth     \\
        heightoneline   =\the\heightoneline \\
        fullheight      =\the\fullheight    \\
        numberoflines   =    \numberoflines};
    \end{tikzpicture}}
\begin{document}
\altframe{i love this sample text}{50pt}
\end{document}
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