trim-image-data

💇‍♀️ Function for trimming/cropping transparent pixels surrounding an image. Very similar to trim-canvas, but accepts and returns an ImageData-instance instead. Also allows specifying custom colors to trim.

Demo

https://trim-image-data.netlify.app

Usage

import trimImageData from 'trim-image-data';

// trim surrounding fully transparent pixels
const trimmedTransparent = trimImageData(imageData);

// trim surrounding white pixels
const trimmedWhite = trimImageData(imageData, {
  trimColor: ([red, green, blue, alpha]) => {
    return red === 255 && green === 255 && blue === 255 && alpha === 255;
  };
});

// supports passing a RGBA array instead of a callback too
const trimmedWhite = trimImageData(imageData, {
  trimColor: [255, 255, 255, 255]
});

// trim any pixel with max alpha
const trimmedDim = trimImageData(imageData, {
  trimColor: ([alpha]) => alpha === 255
});

Installation

# npm
npm install trim-image-data

# yarn
yarn add trim-image-data

# pnpm
pnpm add trim-image-data

API

trimImageData(imageData, trimOptions)

Creates a trimmed version of an ImageData-instance. Trims fully transparent pixels by default. Does not mutate the recieved instance.

Parameters:

• imageData - the ImageData-instance instance to crop

• cropOptions - optional, an object specifying the amount of pixels to crop from each side

  • trimColor([red, green, blue, alpha]) => boolean | trimColor: [r, g, b, a]
    Callback function used to determine if a value should be trimmed or not. Receives an object of RGBA channels and should return a boolean.

    Also accepts a single RGBA-array as a shorthand for a callback that returns true if all channels are equal to the corresponding channel in the array.

Return value:

A new, trimmed ImageData-instance.

Related packages

• crop-image-data - crops ImageData by specified number of pixels. Used as a dependency in trim-image-data.

Credits

A lot of the code in this repo is based on trim-canvas, I just had a need for the same functionality without passing a canvas.