halli

Color gradient generator and picker

Why?

Many moons ago I had a need to efficiently generate colors for particle effects in a game engine. It was a fun problem to work on and resulted in writing some fun code to dynamically generate color gradients that can be used. I published an ImpactJS plugin as well.

Recently, I have found the need for generating colors. So, here we are.

Installation

As a module

$ npm install --save halli

As a script tag

<script type="text/javascript" src="https://clok.sh/assets/js/halli.v0.3.1.min.js" />
<script type="text/javascript">
  // Initialize Halli object
  var picker = new Halli;

  // Generate and draw fade between White and Black with 400 steps
  var fade = picker.genHexArray(0xFFFFFF, 0x000000, 400);

  // Generate the Matlab Jet colormap with 80 steps between each color
  var jet = picker.genMultiHexArray([0x0000FF, 0x00FFFF, 0x00FF00, 0xFFFF00, 0xFF0000, 0x000000], 80);

  // Generate the Matlab HSV colormap with 70 steps between each color
  var hsv = picker.genMultiHexArray([0xFF0000, 0xFFFF00, 0x00FF00, 0x00FFFF, 0x0000FF, 0xFF00FF, 0x000000], 70);
</script>

Demo

See demo

Usage

See Halli class documentation

import { Halli } from 'halli'

// Initialize ColorPicker object
const picker = new Halli()

// Generate and draw fade between White and Black with 400 steps
const fade = picker.genHexArray(0xffffff, 0x000000, 400)

/**
 * Generate the Matlab Jet colormap with 80 steps between each color
 * then render
 */
const jet = picker.genMultiHexArray(
  [0x0000ff, 0x00ffff, 0x00ff00, 0xffff00, 0xff0000, 0x000000],
  80,
)

/**
 * Generate the Matlab HSV colormap with 70 steps between each color
 * then render
 */
const hsv = picker.genMultiHexArray(
  [0xff0000, 0xffff00, 0x00ff00, 0x00ffff, 0x0000ff, 0xff00ff, 0x000000],
  70,
)

/**
 * Regenerate the Matlab HSV colormap in a higher resolution with
 * 27,000 steps between each color.
 * Use the createImageData method to quickly render the colormap
 * with each entry in the array represented by a single pixel.
 */
const pix = picker.genMultiHexArray(
  [0xff0000, 0xffff00, 0x00ff00, 0x00ffff, 0x0000ff, 0xff00ff, 0x000000],
  27000,
)

Development

1. Fork the clok/halli repo
2. Branch & Code
3. Run linters :broom: npm run lint
4. Commit with a Conventional Commit
5. Open a PR

Local Demo

1. Clone the repo
2. npm install
3. npm build
4. open ./demo.html

Why is it named halli?

According to Google translate "gradient" in English translated to Icelandic results in "halli".