chordy-svg

Node JS module for generating guitar chord diagrams in SVG format. Interval names are shown inside the dotted positions.

A <defs> element is written which contains the notes of the chord. This in turn can later be used by the user for audio previews etc.

<defs xmlns="http://www.w3.org/2000/svg" id="tonal">
  <style id="SvgjsStyle1101"/>
  <notes id="tonal-notes">C3:G3:B3:E4:G4</notes>
  <semitones id="tonal-semitones">8:15:19:24:27</semitones>
  <comment id="chord-comment"/>
</defs>

The GitHub page may contain more up to date code than the NPM release. Please check GitHub for the most recent updates.

It uses:

• SVG.js for SVG manipulation.
• svgdom to allow SVG.js to run server-side.
• tonal music theory library for determining the notes and intervals of defined chords.

Demo

You can see this library being used at https://chords.gock.net/

Installation

With npm

npm install chordy-svg --save

Examples

Node Example

Create a node application test.js. This will create a SVG diagram and write the contents to stdout.

const ChordySvg = require("chordy-svg");
 
const voicing = {
  name: "Cmaj7",
  shape: "x35453",
  root: 2,
  comment: "",
};
 
const svg = new ChordySvg(voicing);
const data = svg.svg();
process.stdout.write(data);

If you've cloned the library from GitHub instead of using NPM, you'll need to replace require('chordy-svg') with the correct path, e.g require('./chordy-svg')

Create SVG and write to new file output.svg

node test.js > output.svg

Browser Example

chordy-svg.js is found in dist/ and can be built with npm build.

<div id="image"></div>
 
<script src="https://cdn.jsdelivr.net/npm/@tonaljs/tonal@3.7.2/browser/tonal.min.js"></script>
<script src="https://cdn.jsdelivr.net/npm/svg.js@2.7.1/dist/svg.min.js"></script>
<script src="https://cdn.jsdelivr.net/npm/chordy-svg@latest/dist/chordy-svg.min.js"></script>
<script type="text/javascript">
  // create new svg diagram
  var element = document.getElementById("image");
  var svg = new ChordySvg({ name: "Cmaj7", shape: "x35453", root: 2, comment: "Test comment" }, { target: element });
</script> 

Input

In the example above, we used:

const voicing = {
  name: "Cmaj7",
  shape: "x35453",
  root: 2,
  comment: "",
};

The properties for this object are:

• name is the name of the chord and will be displayed as a title in the SVG
• shape is the shape of the chord, starting from the lowest / thickest string.
  • x: muted or skipped string.
  • 0: open string (open strings not properly tested yet)
  • [0-9a-f]: hexadecimal value refers to fret position. e.g b refers to fret position 11. Only up to fret position 15 (hex f) is permitted.
• root is the root string. 0 refers to the lowest frequency / thickest string. On 6 string guitars with EADGBE tuning, 5 refers to the high E string. In the generated diagram, the dot for this position will be coloured red by default.

A second parameter to the ChordySvg() constructor may be used to set more custom parameters (documentation not complete yet).

Development and Testing

For development and building from source, clone Git repo

git clone https://github.com/andygock/chordy-svg
cd chordy-svg

Run babel script which watches input file and writes to test/dist/chordy-svg.js

npm run start

You can view live updated output of browser with browser-sync

npm run serve:start

You can run further tests with Mocha for plain Node usage (this uses dist/chordy-svg.js).

npm run mocha

You can view live updated directory listing of mocha test output with.

npm run serve:mocha

The serve:* scripts are usually done concurrently with the start or mocha scripts.

Once all is tested well, build to dist/chordy-svg.js, ready for publishing to npm.

npm run build

Run npm run clean to delete all built files and generated SVG images from test/dist/, test/output/ and dist/

Notes

Not fully tested for chords with open strings.