Rectangles.js

Rectangles.js is a collection of functions to work with rectangles. The aim is to have a fast and correct library, which makes it easy to calculate the intersection of two rectangles, the area of a rectangle and so on.

Every rectangle is defined by two cartesian points (x1, y1) on the top left corner and (x2, y2) on the right bottom corner. You have to ensure that x1 <= x2 and y1 <= y2. Otherwise you can use the normalize() function to ensure correct behavior.

Examples

var rect = require('rectangles');
var A = {x1: 20, y1: 20, x2: 100, y2: 100};
var B = {x1: 80, y1: 80, x2: 300, y2: 300};
if (rect.intersect(A, B)) {
  console.log(rect.intersection(A, B)); // Intersection rectangle
} else {
  console.log("no intersection");
}

Functions

intersect(a, b)

Determines if two rectangles intersect

intersection(a, b)

Calculates the intersection rectangle of two rectangles. Rectangles have to intersect to work properly!

normalize(a)

Normalizes a rectangle to ensure x1 < x2 and y1 < y2.

area(a)

Calculates the area of a rectangle

height(a)

Calculates the height of a rectangle

width(a)

Calculates the width of a rectangle

perimater(a)

Calculates the perimeter of a rectangle

center(a)

Calculates the center point of a rectangle

insetBy(a)

Resizes the rectangle by a given value on the center

Installation

Installing Rectangles.js is as easy as cloning this repo or use one of the following commands:

bower install rectangle

or

npm install rectangles

Using Rectangles.js with the browser

<script src="rectangles.js"></script>
<script>
console.log(Rectangles.center(A));
</script>

Using Rectangles.js with require.js

<script src="require.js"></script>
<script>
requirejs(['rectangles.js'],
function(Rectangles) {
    console.log(Rectangles.normalize(128));
});
</script>

Coding Style

As every library I publish, Rectangles.js is also built to be as small as possible after compressing it with Google Closure Compiler in advanced mode. Thus the coding style orientates a little on maxing-out the compression rate. Please make sure you keep this style if you plan to extend the library.

Testing

If you plan to enhance the library, make sure you add test cases and all the previous tests are passing. You can test the library with

npm test

Copyright and licensing

Copyright (c) 2016, Robert Eisele Dual licensed under the MIT or GPL Version 2 licenses.