transform-image-js

transform-image-js is a library to perform transformations on an image file e.g. resize an image within defined constraints and also allows to adjust the quality of image. One of the use cases is when you want to perform a size optimization on the image before uploading.

Getting started

Installing

Using npm:

npm i @shellophobia/transform-image-js

Using yarn:

yarn add @shellophobia/transform-image-js

Using jsDelivr CDN:

<script src="https://cdn.jsdelivr.net/npm/@shellophobia/transform-image-js/lib/transform-image-js.min.js"></script>

Using unpkg CDN:

<script src="https://unpkg.com/@shellophobia/transform-image-js/lib/transform-image-js.min.js"></script>

Usage

Import

in CommonJS:

const transformImage = require("@shellophobia/transform-image-js")

in ES6:

import transformImage from '@shellophobia/transform-image-js';

Resize image to max 500x500 with quality as 0.9:

Vanilla JS and HTML

<input id="demo" type="file" onchange="handleUpload">

function handleUpload(e){
  const file = e.target.files[0];
  // The library will add a property `transformImageJS` on window once you import it
  const transformImage = new transformImageJS.TransformImage({});
  transformImage.resizeImage(file, {maxHeight: 500, maxWidth:500, quality:0.9}).then(res=>{
    //The response returns an object that has the output blob in output attribute and has metadata for image sizes before and after transformation
    console.log(res);
  }).catch(err => {
    // handle error
  });
}

// using async function
async function handleUpload(e) {
  const file = e.target.files[0];
  const transformImage = new transformImageJS.TransformImage({});
  try {
    const res = await transformImage.resizeImage(file, {maxHeight: 500, maxWidth:500, quality:0.9});
    console.log(res);
  } catch(e) {
    // handle error
  }
}

React JSX

import React from "react";
import transformImage from "@shellophobia/transform-image-js";

const handleUpload = async (e) => {
  const file = e.target.files[0];
  console.log(file);
  const transformImage = new transformImage({});
  try {
    const res = await transformImage.resizeImage(file, {maxHeight: 500, maxWidth:500, quality:0.9});
    console.log(res);
  } catch (e) {
    console.log(e);
  }
}

export default function App() {
  return (
    <div className="App">
      <input type="file" onChange={handleUpload} />
    </div>
  );
}

API

Initialization options

Description

Following options can be passed during initialization of transformImage that returns an object on which methods can be called

transformImage(options)

Name	Type	Description	Default
sizeLimit	int	the byte size limit for the input file/blob	16777216 bytes = 16MB
outputType	enum	defines the output object format. Allowed values :- blob/base64/file	blob
allowedFileTypes	[]string	allowed types for the input file/blob e.g. PNG, JPEG, JPG	["jpg", "png", "jpeg"]

Methods

resizeImage(imageFile, options, fileName) => {Promise}

Description:

Resize an image file

Parameters:

Name	Type	Description	Required	Default
image	File/Blob	File object / Blob to be resized	Yes	N/A
options	Object	Additional options described below. The values can also override the TransformImage options	No	{}
fileName	string	Name of the file if outputType is file (Optional)	No	""

Options

Name	Type	Description	Default
maxWidth	int	the max width for the file in px	500
maxHeight	int	the max height for the file in px	500
quality	float	a value between 0 and 1 to denote the quality of the output image	0.9

Returns:

Promise that resolves to the output object

Name	Type	Description
output	blob/base64 string	Blob or base64 string based on configuration
metadata	object	Metadata about initial image dimensions and final image dimensions

Metadata

Name	Type	Description
originalHeight	int	Original image height
originalWidth	int	Original image width
resizedHeight	int	Resized image height
resizedWidth	int	Resized image width

JQuery Plugin

image_compress_plugin is a jquery plugin that allows to add a file upload and compress functionality.

Usage

Importing

<script type="text/javascript" src="https://cdn.jsdelivr.net/npm/@shellophobia/transform-image-js/jquery_plugin/image_compress_plugin.js"></script>

Example

<p>This is a demo for the resize image jquery plugin. Feel free to go through the source code 
<a href="https://github.com/shellophobia/UploadCompressImage/blob/master/jquery_plugin/image_compress_plugin.js">here</a></p>
<div id="fileinput">
  <button class="btn-upload"><i class="fas fa-cloud-upload-alt"></i> Click Here to Upload</button>
  <p class="drag-p">Or Drag N Drop the file</p>
  <input type="file" multiple="true">
</div>
<div id="preview"></div>

<script type="text/javascript" src="https://code.jquery.com/jquery-1.12.4.min.js"></script>
<script type="text/javascript" src="https://cdn.jsdelivr.net/npm/@shellophobia/transform-image-js/jquery_plugin/image_compress_plugin.js"></script>
<script type="text/javascript">
$(document).ready(function() {
  $("#fileinput").uploadFile({
    enablePreview: true,
    appendFileInput: false,
    autoSubmit: false,
    previewSelector: "#preview"
  });
});
</script>

Configuration gist for jquery plugin

License

MIT