[Tex/LaTex] PGF/TikZ arrow line width not consistent with line width

tikz-pgf

I have a document I created several months back, and maybe with a new version of PGF/TikZ it is not working as previously (currently using Arch Linux, TexLive 2011, pgf version 2.10). The fast question is that I have a picture like this:

\begin{tikzpicture}[remember picture,overlay]
\draw [line width=4pt,->,line join=round,line cap=round,red!50] (tl2) -- (tl1);

where tl2 and tl1 are previously defined nodes. Line is displayed right, with a width of 4pt, but the cap is displayed as if the line had a smaller width, obtaining the following:

arrow tip with inconsistent width

The question is, how can I get the tip of the same width as the line?

This may be related with this other question regarding line width in layers, but I'm not sure: Bug in TikZ? Line width on layers

EDIT:

I include minimal compilable code to show the behavior:

\documentclass[a4paper,12pt,oneside]{scrreprt}
\usepackage[left=2.5cm,right=3.5cm,top=3cm,bottom=3cm]{geometry}
\usepackage{tikz}

\begin{document}

I have ...

\begin{tikzpicture}[remember picture,overlay]
\coordinate[xshift=-1.8cm] (tl1) at ([yshift=-2cm]current page.north east);
\coordinate[xshift=-1.8cm,yshift=2cm] (tl2) at (current page.south east);
\draw [line cap=round,line width=4pt,->,red!50] (tl2)  -- (tl1);
\node [above,right=5pt,scale=.7,color=black!50] at (tl1) {timeline};
\end{tikzpicture}

\newpage

\end{document}

I use remember picture because I reuse the tl1 and tl2 nodes defined here.

SOLUTION:

Well, I found pdflatex fails with that rendering, but the combination, for example, of latex + dvipdf works as expected. I checked this with Ubuntu 11.10 and Arch Linux, both running TexLive 2011, so the problem may reside in the TL2011's pdflatex.

Best Answer

An minimal example, which shows a correct arrow tip:

\documentclass{article}
\usepackage{tikz}
\newcommand{\putnode}[2][]{\tikz[overlay,remember picture]{\node (#2) {#1};}}
\begin{document}
\putnode{tl1}

\vspace{2cm}
\putnode{tl2}

\begin{tikzpicture}[remember picture,overlay]
  \draw [line width=4pt,->,line join=round,line cap=round,red!50] (tl2) -- (tl1);
  \node [right of=tl1, color=gray] {\Large\textsf{timeline}};
\end{tikzpicture}
\end{document}

Compiled also with TeX Live 2011 and pgf 2.10:

arrow with tip

Related Solutions

[Tex/LaTex] TikZ: Cropping the Bounding Box

The code adds some completely useless invisible (or rather white) stuff. The lines

\clip(0pt,403pt) -- (389.957pt,403pt) -- (389.957pt,99.6166pt) -- (0pt,99.6166pt) -- (0pt,403pt);
\color[rgb]{1,1,1}
\fill(3.76406pt,399.236pt) -- (380.923pt,399.236pt) -- (380.923pt,253.19pt) -- (3.76406pt,253.19pt) -- (3.76406pt,399.236pt);
\fill(53.4497pt,394.719pt) -- (374.901pt,394.719pt) -- (374.901pt,289.325pt) -- (53.4497pt,289.325pt) -- (53.4497pt,394.719pt);

draw a white background that is larger than the actual picture. TikZ sees that and thinks it is part of the picture. Simply removing/uncommenting these lines removes most of the whitespace.

Near the end of the first scope,

\color[rgb]{1,1,1}
\fill(3.76406pt,249.426pt) -- (386.193pt,249.426pt) -- (386.193pt,103.381pt) -- (3.76406pt,103.381pt) -- (3.76406pt,249.426pt);

does the same. Additionally (near the end of the second scope),

\pgftext[center, base, at={\pgfpoint{220.95pt}{106.392pt}}]{\sffamily\fontsize{9}{0}\selectfont{\textbf{ }}}

adds a blank node below the picture, again enlarging the bounding box.

Removing all those lines gives a tight bounding box.

As far as I know, TikZ cannot do the cropping for you, as it can't know whether the white stuff is intentional or not (there might for example be a dark background behind the image so that white is visible).

[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)

Best Answer

Related Solutions

[Tex/LaTex] TikZ: Cropping the Bounding Box

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

Related Question