SVG Smoother

A utility for adding rounded corners to SVG paths.

Currently only supports hard corners, any pre-existing curve commands are left as is, including corners leading into curve commands. See examples file for a demonstration.

Installation

npm i svg-smoother

Syntax

smoothPath(path, config?)

Smooths a SVG path string.

Parameters

• path A string that matches the SVG d spec. MDN
• config An optional configuration object

Return value

A string matching the SVG d spec.

Example

import { smoothPath } from "svg-smoother";

const path = smoothPath("M 10 10 L 40 10 L 40 40", { radius: 10 });

This function also integrates nicely with React or other frameworks like so:

function Path() {
    return <path d={smoothPath("M 10 10 L 40 10 L 40 40")} />;
}

smoothPathElement(element, config?)

A helper function when working with existing DOM elements.

Parameters

• element An SVG Path DOM Element.
• config An optional configuration object

Return value

An SVG Path DOM Element.

Example

import { smoothPathElement } from "svg-smoother";

const path = document.querySelector("path");
smoothPathElement(path);

smoothPolygon(polygon, config?)

Takes an array of number pairs and converts it into a smoothed SVG path shape.

This function is particularly helpful if you are using some other JS to generate a path dynamically as a list of x,y pairs that you want to smooth.

Parameters

• polygon An array of number pairs (e.g. [[0, 0], [10, 20], [30, 40]]) that represent absolute values of a polygon shape. Similar syntax to the CSS polygon command. Note that the values are not treated as percentages like in CSS but if you provide numbers between 0-100 it does work just the same.
• config An optional configuration object

Return value

A string matching the SVG d spec.

Example

import { smoothPolygon } from "svg-smoother";

const path = smoothPolygon([
    [10, 10],
    [40, 10],
    [40, 40],
]);

const path = smoothPolygon(
    [
        [10, 10],
        [40, 10],
        [40, 40],
    ],
    {
        closePath: false,
    }
);

Configuration object

• radius A number that represents the amount of coordinate points to round the corners by. These values work much like setting CSSs border-radius property. Defaults to 10 if not provided

• reduceCommands A boolean that if set to true will attempt to replace any Line commands in the resulting path with Horizontal and Vertical commands to reduce the resulting path length. Defaults to true if not provided.

  Turing this off can be helpful if you need a stable set of returned commands for animation states with CSS transitions.

• numberAccuracy Set the number of decimal places to round values to when outputting the new path. Defaults to 3 decimal places if not provided.

• closePath Only applies to the smoothPolygon command. A boolean that when set to true closes the provided path into a complete shape. When false it is left open as a line. Defaults to true if not provided.

• preventOverflow A boolean that controls if your radius value should be constrained to not be larger than the line it is smoothing. Defaults to true, preventing overflow. See examples file for an example of this in use.

• allowEllipse A boolean to control if smoothing should stick to perfect circles or create ellipses. Defaults to true so smoothing will create mismatched radius values. If it helps with understanding it is similar to having a dual value CSS border-radius vs a single value, border-radius: 10px; vs border-radius: 10px / 20px;. Also check the examples file for a visual example of this in practice.

Planned features

• Deal with radius values that are larger than the preceding line
• Investigate support for smoothing into and out of curve commands
• Add more examples
• Measure and improve performance
• Add an optimization step to remove large floats, and restore usage of H and V commands

Support

Versions of Node >= 14 are tested to work, but testing lower versions is limited because of a testing dependency on JSDOM which has a minimum Node version of 14. SVG Smoother itself is likely to work on older versions than that.

Browser support requires support of Object.values

License

GNU General Public License