Custom Gradient

This example takes you through creating your own custom color gradient and generate valid CSS code for it. It also shows how to generate intermediate color values in between color stops. By default, getColor() will assume a normalized input value from 0 to 1, but if minimum and maximum bounds are given, it will automatically interpolate between them.

Installation

Follow these steps to create a new project workspace and install the viridis dependency to run this example.

# Create and open project folder
mkdir Gradient_demo
cd Gradient_demo
# Initialize project and install dependencies
npm init -y
npm i viridis@1.1.7
# Create and open source file
touch "Gradient.mjs"
open "Gradient.mjs"
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Source

Copy and paste this source code into Gradient.mjs.

import { Color, Gradient } from 'viridis';

// Define a custom gradient using an array of colors
const RGB_Gradient = new Gradient([
    new Color(255, 0, 0), // 0.0
    new Color(0, 255, 0), // 0.5
    new Color(0, 0, 255), // 1.0
]);

// Generate valid CSS code for this color gradient
console.log('CSS code        : ' + RGB_Gradient);
console.log('CSS code [45deg]: ' + RGB_Gradient.toString(45));

// Show the internal array of color stops
console.log('Color Stops', RGB_Gradient.colors);

// Generate a short list of intermediate color values
// Gradient will automatically interpolate if given
// a minimum and maximum bound. (1, N)
const N = 5;
for (let i = 1; i <= N; i++) {
    console.log(i + ' = ' + RGB_Gradient.getColor(i, 1, N));
}
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Output

In Gradient_demo/, execute Gradient.mjs with NodeJS to generate an output.

node "Gradient.mjs"
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You should expect to see an output similar to the one below.

CSS code        : linear-gradient(90deg,rgba(255,0,0,100%),rgba(0,255,0,100%),rgba(0,0,255,100%))
CSS code [45deg]: linear-gradient(45deg,rgba(255,0,0,100%),rgba(0,255,0,100%),rgba(0,0,255,100%))
Color Stops [
  Color { red: 255, green: 0, blue: 0, alpha: 100 },
  Color { red: 0, green: 255, blue: 0, alpha: 100 },
  Color { red: 0, green: 0, blue: 255, alpha: 100 }
]
1 = rgba(255,0,0,100%)
2 = rgba(127,127,0,100%)
3 = rgba(0,255,0,100%)
4 = rgba(0,127,127,100%)
5 = rgba(0,0,255,100%)
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