[Tex/LaTex] Placing a rectangular node in tikz by specifying two opposing corners

nodespositioningtikz-pgf

\documentclass[border=10pt]{standalone}
\usepackage{tikz}
\begin{document}
  \begin{tikzpicture}
    \coordinate (bottom left) at (10,10);
    \coordinate (top right) at (20,20);
    \draw[rounded corners,fill=black] (bottom left) rectangle (top right);
  \end{tikzpicture}
\end{document}

the line

    \draw[rounded corners,fill=black] (bottom left) rectangle (top right);

draws a black rectangle with rounded corners between the coordinates (bottom left) and (top right).

What's the most concise way to define a node with exactly the same shape, position and size as a rectangle defined with '\draw' and 'rectangle' (as above)?

The solution should …

use the provided coordinates with manual calculations,
work with rounded corners,
place the node's coordinates (n.north, n.west, …) were expected, and
be as concise (and elegant) as possible.

Best Answer

If I understood you correctly, you like to determine rectangle with size determined with two coordinates (bottom left, top right). If this is a case, you can obtain this as follows:

\documentclass[tikz,border=5mm]{standalone}
    \usetikzlibrary{fit}
\begin{document}
    \begin{tikzpicture}[
mynode/.style 2 args = {
    draw, rounded corners, fill=black, 
    inner sep=0pt, outer sep=0pt,
    fit=(#1) (#2)}
                        ]
\coordinate (bottom left) at (10,10);
\coordinate (top right) at (20,20);
    \node[mynode={bottom left}{top right}] {};
    \end{tikzpicture}
\end{document}

enter image description here

Of course, you can define rectangle size on different way, for example width minimum width, minimum height, text width and text height etc.

For fiting node on given coordinates I use tikzlibrary{fit} and set inner node separation to 0pt. The node aslo have all anchors as defined for rectangular shape.

Comment: Declare rectangle nodes on such a way may lead to problem with placing of node's contents. They can be displaced from center of node.

Related Solutions

[Tex/LaTex] Drawing a triangle with rounded corners in TikZ

Make the radius of the rounded corners smaller. Remove =10mm and you will see the instant effect. Also, in your case, I find no need to load the xcolor package since it is used internally by tikz, unless, as noted by Alain Matthes, you use some of its options for naming your colors. You can uncomment it if you like. The libraries are not needed here, too, so I commented them out.

Here is your figure when the 10mm is dropped.

enter image description here

And here is one with scaling (not really necessary, just for demonstration purposes).

%\documentclass{article}

\documentclass[border=5]{standalone}

\usepackage{tikz}
%\usepackage{xcolor}
%\usetikzlibrary{arrows,shapes,snakes,automata,backgrounds,petri}

\begin{document}
\begin{tikzpicture}[scale=3]
    \draw [rounded corners,fill=gray!20] (0,0)--(1,0)--(0.5,1)--cycle;
\end{tikzpicture}
\end{document}

enter image description here

Here I have scaled the figure up to 3 since your figure is too small.

To make a point, see what happens when I scale the figure up by 5 and set rounded corners=10mm.

enter image description here

[Tex/LaTex] Tikz coordinates relative to a node, and outside it

That's what the calc library is for:

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{calc}
\begin{document}
\begin{tikzpicture}
\node [draw] (X) {X node};
\draw (X.north west) -- ($(X.north west)!cos(45)!45:(X.north east)$) -- (X.north east);
\end{tikzpicture}
\end{document}

The syntax is as follows:

($(A)!<fraction>!(B)$) referst to the point that lies <fraction> of the way along the line from (A) to (B). ($(A)!0.5!(B)$) would refer to the midpoint of the connecting line, ($(A)!0!(B)$) refers to (A), and ($(A)!1!(B)$) refers to (B). If the number is greater than 1 or less than 0, the path is extrapolated.

The syntax ($(A)!<fraction>!<angle>:(B)$) refers to the point that lies <fraction> of the way along the line from (A) to (B) after that line has been rotated around (A) by <angle> degrees.

For a right-angled triangle, we know that if the angle between the hypotenuse and the adjacent side is 45°, the length of the adjacent side is cos(45)*h.

Similarly for other angles:

\documentclass[border=5mm]{standalone}
\usepackage{tikz}
\usetikzlibrary{calc}
\begin{document}
\begin{tikzpicture}
\node [draw, outer sep=0pt] (X) {X node};
\foreach \angle in {15,30,...,75}{
    \draw [red!\angle!blue] (X.north west) -- ($(X.north west)!cos(\angle)!\angle:(X.north east)$) -- (X.north east);
}
\end{tikzpicture}
\end{document}

Best Answer

Related Solutions

[Tex/LaTex] Drawing a triangle with rounded corners in TikZ

[Tex/LaTex] Tikz coordinates relative to a node, and outside it

Related Question