TikZ-PGF Arrows – Easy Method to Place Arrow Tips Outside Drawn Line

tikz-arrowstikz-pgf

I regularly need to represent mathematical intervals, and I find annoying to have to manually tweak the opened brackets (see MWE below).

Is there any way to :

define a new arrow tip that starts at the end of the line and extends further (thus exceeding the start and/or stop coordinates) ;
having this new arrow tip scalable, to avoid ugly rendering like the one of the MWE ;
bonus : having transparency group included by design in the code.

I've searched here, and finally found TikZ: Precisely controlling arrow tip position, but the syntax has changed and I'm not skilled enough to adapt it to the new one.

\documentclass{article}
\usepackage{tikz, amssymb}
\usetikzlibrary{arrows.meta}


\begin{document}
     \tikzset{
        interv oo/.style={{Bracket[reversed, sharp, length=.75ex]}-{Bracket[reversed, sharp, length=.75ex]}, shorten <=-.75ex, shorten >=-0.75ex},
        interv of/.style={{Bracket[reversed, sharp, length=.75ex]}-{Bracket[sharp, length=.75ex]}, shorten <=-.75ex},
        interv fo/.style={{Bracket[sharp, length=.75ex]}-{Bracket[reversed, sharp, length=.75ex]}, shorten >=-0.75ex},
        interv ff/.style={{Bracket[sharp, length=.75ex]}-{Bracket[sharp, length=.75ex]}},
        interv oi/.style={{Bracket[reversed, sharp, length=.75ex]}-, shorten <=-.75ex},
        interv io/.style={-{Bracket[sharp, length=.75ex]}, shorten >=-0.75ex},
        interv fi/.style={{Bracket[sharp, length=.75ex]}-},
        interv if/.style={-{Bracket[sharp, length=.75ex]}},
        label/.style={below, font=\footnotesize} }
    
    \begin{tikzpicture}
        \draw (-3,0) -- (3,0) node[anchor=south] {$\mathbb{R}$};
        \foreach \x in {-1,0,1} \draw (\x,2pt) -- (\x, -2pt) node[anchor=north] {$\x$};
        \begin{scope}[opacity=.5, transparency group]
            \draw[line width=3pt, blue, interv oo] (-1,0) -- (1,0);
        \end{scope}
    \end{tikzpicture}
\end{document}

Many thanks in advance.

Edit : here is what I finally came to. Seems satisfying enough to me. With usage of tabularray that was just put to my knowledge.

\documentclass[12pt,a4paper]{book}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{mathpazo}
\usepackage{geometry}
\usepackage[french]{babel}
\usepackage{tikz}
\usetikzlibrary{arrows.meta, arrows}
\usepackage{tabularray}
\frenchbsetup{StandardLists=true}   % Resolves conflict between babel and enumitem

\geometry{
    top=1.5cm, bottom=1.5cm, left=1cm, right=1cm,
    headheight=1cm, headsep=0.5cm,
    footskip=1cm}

\setlength{\parindent}{0mm} % No paragraphe indentation

\begin{document}
    
    \tikzset{
        interv oo/.style={{Bracket[reversed, sharp, length=0pt 2, sep=0pt -1.5]}-{Bracket[reversed, sharp, length=0pt 2, sep=0pt -1.5]}},
        interv of/.style={{Bracket[reversed, sharp, length=0pt 2, sep=0pt -1.5]}-{Bracket[sharp, length=0pt 2]}},
        interv fo/.style={{Bracket[sharp, length=0pt 2]}-{Bracket[reversed, sharp, length=0pt 2, sep=0pt -1.5]}},
        interv ff/.style={{Bracket[sharp, length=0pt 2]}-{Bracket[sharp, length=0pt 2]}},
        interv oi/.style={{Bracket[reversed, sharp, length=0pt 2, sep=0pt -1.5]}-},
        interv io/.style={-{Bracket[reversed, sharp, length=0pt 2, sep=0pt -1.5]}},
        interv fi/.style={{Bracket[sharp, length=0pt 2]}-},
        interv if/.style={-{Bracket[sharp, length=0pt 2]}},
        label/.style={below, font=\footnotesize} }
    
    Compléter le tableau suivant:

    \begin{tblr}{hlines, vlines,
                cell{2-5}{1,4}={mode=dmath},
                colspec={X[1,c,m] X[3,c,m] X[2.2,c,m] X[1.2,c,m]},
                rowsep=10pt,
                row{1} = {font=\bfseries, rowsep=4pt},
            }
        Inégalité & Phrase & Représentation graphique & Intervalle \\

        \ldots x\ldots & {$x$ est un réel\\ strictement supérieur à $-2$\\ et strictement inférieur à $4$} & \begin{tikzpicture}[scale=0.5, >=stealth, baseline={([yshift=-.5ex]current bounding box.center)}]
                % Bornes
                \def\xm{-4.9}
                \def\xM{-\xm}
                % Intervalle
                \draw[line width=4.5pt, green, interv oo] (-2,0) -- (4,0) ;
                % Repère
                \draw[thick,->] (\xm,0) -- (\xM,0) ;
                \foreach \x in {-4,...,4} { \draw (\x, -2mm) -- ++(0, 4mm) ; }
                \node[label] at (0,0) {0} ;
                \node[label] at (1,0) {1} ;
                \node[label, above, white] (0,0) {0} ; % Pour équilibrer le dessin verticalement
        \end{tikzpicture} & x\in\ldots \\
    
        & & \begin{tikzpicture}[scale=0.5, >=stealth, baseline={([yshift=-.5ex]current bounding box.center)}]
            % Bornes
            \def\xm{-4.9}
            \def\xM{-\xm}
            % Intervalle
            \draw[line width=2.5pt, red, interv of] (-2,0) -- (4,0) ;
            % Repère
            \draw[thick,->] (\xm,0) -- (\xM,0) ;
            \foreach \x in {-4,...,4} { \draw (\x, -2mm) -- ++(0, 4mm) ; }
            \node[label] at (0,0) {0} ;
            \node[label] at (1,0) {1} ;
            \node[label, above, white] (0,0) {0} ; % Pour équilibrer le dessin verticalement
        \end{tikzpicture} & \\
    
        & & \begin{tikzpicture}[scale=0.5, >=stealth, baseline={([yshift=-.5ex]current bounding box.center)}]
            % Bornes
            \def\xm{-4.9}
            \def\xM{-\xm}
            % Intervalle
            \draw[line width=2.5pt, orange, interv fo] (-2,0) -- (4,0) ;
            % Repère
            \draw[thick,->] (\xm,0) -- (\xM,0) ;
            \foreach \x in {-4,...,4} { \draw (\x, -2mm) -- ++(0, 4mm) ; }
            \node[label] at (0,0) {0} ;
            \node[label] at (1,0) {1} ;
            \node[label, above, white] (0,0) {0} ; % Pour équilibrer le dessin verticalement
        \end{tikzpicture} & \\
    
        & & \begin{tikzpicture}[scale=0.5, >=stealth, baseline={([yshift=-.5ex]current bounding box.center)}]
            % Bornes
            \def\xm{-4.9}
            \def\xM{-\xm}
            % Intervalle
            \draw[line width=2.5pt, yellow!70!orange, interv ff] (-2,0) -- (4,0) ;
            % Repère
            \draw[thick,->] (\xm,0) -- (\xM,0) ;
            \foreach \x in {-4,...,4} { \draw (\x, -2mm) -- ++(0, 4mm) ; }
            \node[label] at (0,0) {0} ;
            \node[label] at (1,0) {1} ;
            \node[label, above, white] (0,0) {0} ; % Pour équilibrer le dessin verticalement
        \end{tikzpicture} & \\
    
        & & \begin{tikzpicture}[scale=0.5, >=stealth, baseline={([yshift=-.5ex]current bounding box.center)}]
            % Bornes
            \def\xm{-4.9}
            \def\xM{-\xm}
            % Intervalle
            \begin{scope}[transparency group, opacity=.5]
                \draw[line width=2.5pt, cyan, interv oi] (-2,0) -- (\xM,0) ;
            \end{scope}
            % Repère
            \draw[thick,->] (\xm,0) -- (\xM,0) ;
            \foreach \x in {-4,...,4} { \draw (\x, -2mm) -- ++(0, 4mm) ; }
            \node[label] at (0,0) {0} ;
            \node[label] at (1,0) {1} ;
            \node[label, above, white] (0,0) {0} ; % Pour équilibrer le dessin verticalement
        \end{tikzpicture} & \\
    
        & & \begin{tikzpicture}[scale=0.5, >=stealth, baseline={([yshift=-.5ex]current bounding box.center)}]
            % Bornes
            \def\xm{-4.9}
            \def\xM{-\xm}
            % Intervalle
            \draw[line width=2.5pt, purple, interv io] (\xm,0) -- (4,0) ;
            % Repère
            \draw[thick,->] (\xm,0) -- (\xM,0) ;
            \foreach \x in {-4,...,4} { \draw (\x, -2mm) -- ++(0, 4mm) ; }
            \node[label] at (0,0) {0} ;
            \node[label] at (1,0) {1} ;
            \node[label, above, white] (0,0) {0} ; % Pour équilibrer le dessin verticalement
        \end{tikzpicture} & \\
    
        & & \begin{tikzpicture}[scale=0.5, >=stealth, baseline={([yshift=-.5ex]current bounding box.center)}]
            % Bornes
            \def\xm{-4.9}
            \def\xM{-\xm}
            % Intervalle
            \begin{scope}[transparency group, opacity=.5]
                \draw[line width=2.5pt, gray, interv fi] (-2,0) -- (\xM,0) ;
            \end{scope}
            % Repère
            \draw[thick,->] (\xm,0) -- (\xM,0) ;
            \foreach \x in {-4,...,4} { \draw (\x, -2mm) -- ++(0, 4mm) ; }
            \node[label] at (0,0) {0} ;
            \node[label] at (1,0) {1} ;
            \node[label, above, white] (0,0) {0} ; % Pour équilibrer le dessin verticalement
        \end{tikzpicture} & \\
    
        & & \begin{tikzpicture}[scale=0.5, >=stealth, baseline={([yshift=-.5ex]current bounding box.center)}]
            % Bornes
            \def\xm{-4.9}
            \def\xM{-\xm}
            % Intervalle
            \begin{scope}[transparency group, opacity=.5]
                \draw[line width=2.5pt, blue!50!white, interv if] (\xm,0) -- (4,0) ;
            \end{scope}
            % Repère
            \draw[thick,->] (\xm,0) -- (\xM,0) ;
            \foreach \x in {-4,...,4} { \draw (\x, -2mm) -- ++(0, 4mm) ; }
            \node[label] at (0,0) {0} ;
            \node[label] at (1,0) {1} ;
            \node[label, above, white] (0,0) {0} ; % Pour équilibrer le dessin verticalement
        \end{tikzpicture} & \\
    \end{tblr}

\end{document}

Best Answer

You can do that with the sep option(moves the arrow head away from the endpoint coordinate of the line) - it uses the same syntax as length. If you want absolute length of the head, you can change 0pt 1 back to .75ex (or maybe use em or pt for a horizontal distance)

\documentclass[tikz, border=1 cm]{standalone}
\usepackage{amssymb}
\usetikzlibrary{arrows.meta}
\begin{document}
     \tikzset{
        interv oo/.style={{Bracket[reversed, sharp, length=0pt 1, sep=0pt -1]}-{Bracket[reversed, sharp, length=0pt 1, sep=0pt -1]}},
}    
    \begin{tikzpicture}
        \draw (-3,0) -- (3,0) node[anchor=south] {$\mathbb{R}$};
        \foreach \x in {-1,0,1} \draw (\x,2pt) -- (\x, -2pt) node[anchor=north] {$\x$};
        \begin{scope}[opacity=.5, transparency group]
            \draw[line width=5pt, blue, interv oo] (-1,0) -- (1,0);
        \end{scope}
    \end{tikzpicture}
\end{document}

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)

TikZ-PGF – Placing Node (Entity) Label on the Inside in TikZ/ERD

I guess this is one way of doing it:

\documentclass[tikz,border=5]{standalone}

\usetikzlibrary{matrix}
\begin{document}
\tikzset{
    entity/.code={
        \tikzset{
            rounded corners,             
            name=#1,
            inner sep=2pt,
            every entity/.try,
        }%
        \def\entityname{#1}%
    },
    entity anchor/.style={matrix anchor=#1},
    every entity/.style={
            draw,
    },
    every property/.style={
        inner xsep=0.20cm, inner ysep=0.075cm, anchor=west, text width=1.75in
    }
}
\def\property#1{\node[name=\entityname-#1, every property/.try]{\propertysplit#1;};}
\def\properties{\begingroup\catcode`\_=11\relax\processproperties}
\def\processproperties#1{\endgroup%
    \gdef\propertycode{}%
    \foreach \p in {#1}{%
        \expandafter\expandafter\expandafter\gdef\expandafter\expandafter\expandafter\propertycode%
            \expandafter\expandafter\expandafter{\expandafter\propertycode\expandafter\property\expandafter{\p}\\}%
    }%
    \propertycode%
}
\def\propertysplit#1:#2;{#1:\hfill#2}

\def\entitynamenode{%
\node[every entity name/.try] (\entityname-name) {\entityname};
\draw (\entityname-name.south west) -- (\entityname-name.south east);
\\[1ex]
}
\tikzset{
  every entity name/.style={every property/.try, align=center}
}

\begin{tikzpicture}[every node/.style={font=\ttfamily}, node distance=0.5in]
\matrix [entity=Employee] {
    \entitynamenode
    \properties{
        Username :  varchar(255),
        Password :  varchar(255),        
        Name :  varchar(255),
        LastName :  varchar(255)
    }
};
\end{tikzpicture}   

\end{document}

enter image description here

Best Answer

Related Solutions

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

TikZ-PGF – Placing Node (Entity) Label on the Inside in TikZ/ERD

Related Question