Image Resize

JavaScript library for image resizing. It allows you to resize images to a given size or scale by using the HTML5 Canvas API.

Click here to see the demo.

Installation

It is available as a package on NPM for use with a module bundler.

# NPM
$ npm install --save @cevad-tokatli/image-resize

# Yarn
$ yarn add @cevad-tokatli/image-resize

Usage

You can simply import the module and call resize method to resize an image.

import { resize, toImage } from '@cevad-tokatli/image-resize'

resize('image.jpg', {
    scale: 50,
})
.then(canvas => toImage(canvas))
.then(image => {
    document.body.appendChild(image)
})

Methods

The module provides the following methods to resize image and convert it to different formats.

Resize

resize(input: HTMLImageElement | HTMLCanvasElement | File | string, options?: ResizeOptions): Promise<HTMLCanvasElement>

Resizes the input and returns a Promise that resolves a canvas element which can be converted to a file, image, blob or base64 code by using the provided convert methods (toFile, toImage, toBlob, toBase64).

Method Arguments

input

Image to be resized. It can be given in five different ways.

An Image Element:

import { resize } from '@cevad-tokatli/image-resize'

const img = new Image()
img.addEventListener('load', () => {
    resize(img)
})
img.src = 'image.jpg'

A Canvas Element:

import { resize } from '@cevad-tokatli/image-resize'

const img = document.querySelector('img')
const canvas = document.createElement('canvas')
canvas.getContext('2d').drawImage(img, 0, 0, img.width, img.height);

resize(canvas)

A File:

import { resize } from '@cevad-tokatli/image-resize'

const file = document.querySelector('input[type="file"]').files[0]

resize(file)

An Image Source (String):

import { resize } from '@cevad-tokatli/image-resize'

resize('image.jpg')

A Base64 Code (String):

import { resize } from '@cevad-tokatli/image-resize'

resize('data:image/jpeg;base64,/9j/4AAQSkZJRgABAQAAAQAB...')

options

Dimensions or scale by which to resize the image.

Options Properties:

width: number It must be a px value. If it is null, resizes width according to height.

height: number It must be a px value. If it is null, resizes height according to width.

scale: number It scales images in both dimensions at given ratio.

Convert Methods

toFile(canvas: HTMLCanvasElement, fileName?: string): Promise<File>

Converts the given canvas element to a file object.

toImage(canvas: HTMLCanvasElement): Promise<HTMLImageElement>

Converts the given canvas element to an image element.

toBlob(canvas: HTMLCanvasElement): Promise<string>

Converts the given canvas element to a blob URL.

toBase64(canvas: HTMLCanvasElement): string

Converts the given canvas element to base64 code.

License

Image Resize is provided under the MIT License.