Node shape trapezium in TikZ
Trapezium shape is a part of the shapes.geometric TikZ library, so to work with this shape, we need to declare the library. We need to add the following piece of code after the TikZ package declaration:
\usetikzlibrary{shapes.geometric}A trapezium shape can be drawn by using the option trapezium to the \node command. Following line creates a trapezium node named (t) at coordinate (0,0).
\documentclass[border=0.2cm]{standalone}
\usepackage{tikz}
\usetikzlibrary{shapes.geometric}
\begin{document}
\begin{tikzpicture}
\node[trapezium] (t) at (0,0) {};
\end{tikzpicture}
\end{document}
Compiling this line of code displays nothing. The trapezium node will be drawn only if we provide draw option to the node command as follows:
\documentclass[border=0.2cm]{standalone}
\usepackage{tikz}
\usetikzlibrary{shapes.geometric}
\begin{document}
\begin{tikzpicture}
\node[trapezium,draw] (t) at (0,0) {};
\end{tikzpicture}
\end{document}
Add text to the trapezium node
The previous code creates a trapezium node with empty content. Text can be added inside the trapezium node by putting it between the curly braces {} as follows:
\documentclass[border=0.2cm]{standalone}
\usepackage{tikz}
\usetikzlibrary{shapes.geometric}
\begin{document}
\begin{tikzpicture}
\node[trapezium,draw] (t) at (0,0) {Trapezium};
\end{tikzpicture}
\end{document}
To fit the text inside the shape, this code yields to a trapezium with a size depends on its content:
Change text color of the trapezium node
In the previous section, we have added content to the trapezium node and now we would like to change the text color. This can be achieved by providing the option text = <color> to the \node command:
\documentclass[border=0.2cm]{standalone}
\usepackage{tikz}
\usetikzlibrary{shapes.geometric}
\begin{document}
\begin{tikzpicture}
\node[trapezium,
draw,
text = brown] (t) at (0,0) {Trapezium};
\end{tikzpicture}
\end{document}
Add filling color to a node
The trapezium node can be filled with any color using the option fill = <color>. Here is an illustrative example of a light teal filling with our brown text:
\documentclass[border=0.2cm]{standalone}
\usepackage{tikz}
\usetikzlibrary{shapes.geometric}
\begin{document}
\begin{tikzpicture}
\node[trapezium,
draw,
text = brown,
fill = teal!20] (t) at (0,0) {Trapezium};
\end{tikzpicture}
\end{document}
Change the border line color of trapezium
The trapezium border color can be modified (default is black) by providing the color name to the draw option draw = <color>. Here is an example of a trapezium filled with light teal, has brown text and blue borders:
\documentclass[border=0.2cm]{standalone}
\usepackage{tikz}
\usetikzlibrary{shapes.geometric}
\begin{document}
\begin{tikzpicture}
\node[trapezium,
draw = blue!80,
text = brown,
fill = teal!20] (t) at (0,0) {Trapezium};
\end{tikzpicture}
\end{document}
Change the size of a trapezium node
We mentioned above that the size of a trapezium depends on its content. This is always true and we can set only the minimum size of a trapezium.
We can arrange a minimum size for its bottom width with minimum width option, and similarly, we can set its height by using minimum height option.
Below, we set the stretch option to true, minimum width value to 4 cm and the minimum height value to 3 cm.
\documentclass[border=0.2cm]{standalone}
\usepackage{tikz}
\usetikzlibrary{shapes.geometric}
\begin{document}
\begin{tikzpicture}
\node[trapezium,
draw = blue!80,
text = brown,
fill = teal!20,
trapezium stretches = true,
minimum width = 3cm,
minimum height = 1.5cm] (t) at (0,0) {Trapezium};
\end{tikzpicture}
\end{document}
Change trapezium angles
We can also change the lower internal angles of the trapezium using trapezium left angle and trapezium right angle options. However, to enforce these angles, we need to remove the trapezium stretches option, and therefore, remove one of the minimum size options.
Here is an example of a trapezium with a minimum width value of 3 cm, a 120degrees left internal angle and a 60degrees right internal angle. (Since the angles are adding up to 180degrees, our shape is also a parallelogram.)
\documentclass[border=0.2cm]{standalone}
\usepackage{tikz}
\usetikzlibrary{shapes.geometric}
\begin{document}
\begin{tikzpicture}
\node[trapezium,
draw = blue!80,
text = brown,
fill = teal!20,
minimum width = 3cm,
trapezium left angle = 120,
trapezium right angle = 60] (t) at (0,0) {Trapezium};
\end{tikzpicture}
\end{document}
If we need both of the lower internal angles to be the same, we can use trapezium angle option. Here is an example of a trapezium with 45degrees lower internal angles.
\documentclass[border=0.2cm]{standalone}
\usepackage{tikz}
\usetikzlibrary{shapes.geometric}
\begin{document}
\begin{tikzpicture}
\node[trapezium,
draw = blue!80,
text = brown,
fill = teal!20,
minimum width = 3cm,
trapezium angle = 45] (t) at (0,0) {Trapezium};
\end{tikzpicture}
\end{document}
Anchors of a trapezium node
The advantage of using a node trapezium is that it defines a set of anchors that we can use to get coordinates of the node borders or to position nodes with accuracy with respect to given coordinates. By default, node center is positioned at the provided coordinates ((0,0) for the previous examples).
(t.west) represents the coordinates of the point located at the west of the trapezium node where t is the node name. We can also use angles where (t.0) is the coordinates of the point located at the east of the trapezium node.
Adding anchor = south will place the node point (t.south) at the provided coordinate (0,0). Check this post: how to annotate an image in LaTeX (Positioning Nodes using Anchors section).
Outer separation
The above anchors can be moved outside the node border by adding outer sep = <value> to the node command. Here is an example of anchors moved outside the node border with 10pt.
