README

ngx-image-compress

Angular utility for compressing images to a satisfying size, that you can choose

Import

npm i ngx-image-compress

For visualizing code examples:
https://stackblitz.com/edit/ngx-image-compress

For performance tests, in particular tests on mobile, please do not use stackbliz, put rather this optimised demo, equivalent to what you get in a production-ready application:
https://image-library.app

Angular 13+ do not need any module import. Inject the service in the constructor of your component directly.
For any angular version before 13, you should first import the service in your module, like this:

import {NgxImageCompressService} from "ngx-image-compress";

@NgModule({
  declarations: [AppComponent],
  imports: [BrowserModule],
  providers: [NgxImageCompressService],
  bootstrap: [AppComponent],
})
export class AppModule {
}

Usage

Here how to use the service in your component.

Using upload and compress function, independently

This option is giving control over the compression process.

compressFile() signature is detailed here

import {Component} from "@angular/core";
import {NgxImageCompressService} from "ngx-image-compress";

@Component({
  selector: "app-root",
  template: `
      <button (click)="compressFile()">Upload and compress Image</button>
      <img [src]="imgResultBeforeCompression" *ngIf="imgResultBeforeCompression" />
      <img [src]="imgResultAfterCompression" *ngIf="imgResultAfterCompression"  />
  `,
})
export class AppComponent {

  constructor(private imageCompress: NgxImageCompressService) {
  }

  imgResultBeforeCompression: string = "";
  imgResultAfterCompression: string = "";

  compressFile() {
    this.imageCompress.uploadFile().then(
      ({image, orientation}) => {

        this.imgResultBeforeCompression = image;
        console.log("Size in bytes of the uploaded image was:", this.imageCompress.byteCount(image));

        this.imageCompress
          .compressFile(image, orientation, 50, 50) // 50% ratio, 50% quality
          .then(
            (compressedImage) => {
              this.imgResultAfterCompression = compressedImage;
              console.log("Size in bytes after compression is now:", this.imageCompress.byteCount(compressedImage));
            }
          );
      }
    );
  }
}

Performing a single upload, and compressing automatically to a given max size

Quicker method.

Getting directly an image at a maximum of "X" MegaBytes, using an optimised algorithm:

import {Component} from "@angular/core";
import {NgxImageCompressService} from "ngx-image-compress";

@Component({
  selector: "app-root",
  template: `
      <button (click)="compressFile()">Upload and compress Image</button>
      <img [src]="imgResult" *ngIf="imgResult" />
  `,
})
export class AppComponent {

  constructor(private imageCompress: NgxImageCompressService) {
  }

  imgResult: string = "";

  compressFile() {
    const MAX_MEGABYTE = 2;
    this.imageCompress
      .uploadAndGetImageWithMaxSize(MAX_MEGABYTE) // this function can provide debug information using (MAX_MEGABYTE,true) parameters
      .then(
        (result: string) => {
          this.imgResult = result;
        },
        (result: string) => {
          console.error('The compression algorithm didn\'t succed! The best size we can do is', this.imageCompress.byteCount(result), 'bytes')
          this.imgResult = result;
        });
  }
}

Multiple files support

For uploading multiple files, instead of using

this.imageCompress.uploadFile()
  .then((singleFile: { image: string, orientation: number }) => //...

You can use

this.imageCompress.uploadMultipleFiles()
  .then((arrayOfFiles: { image: string, orientation: number }[]) => //...

compressFile() signature

The signature of compressFile() is:

compressFile(image, orientation, ratio, quality, maxWidth, maxHeight)

Parameter	Type	Description
image	string	DataUrl (string) representing the image
orientation	number	EXIF Orientation value using the DOC_ORIENTATION enum value
ratio	number	Maximum scale factor as a percentage (optional, default: 50) ¹
quality	number	JPEG quality factor as a percentage (optional, default: 50) ²
maxWidth	number	Maximum width in pixels if you need to resize (optional, default: 0 - no resize)
maxHeight	number	Maximum height in pixels if you need to resize (optional, default: 0 - no resize)

[1] Ratio: "50" will decrease the resolution of each dimension by 2, i.e.: image of 2000 X 1500 pixels will become 1000 X 750 pixels, while the whole resolution will be reduced by 4.

[2] Quality: For more info about this parameter, read this guide

How it works under the hood?

We will use Renderer2, and transform the image using HTML canvas encrustation. In fact you can use the static version in the library and import renderer by yourself, or remplace it with another DOM abstraction, using RendererFactory2.

There are mainly two advantage for using Renderer2 abstraction over direct DOM manipulation, using ElementRef or window.document directly.

Angular keeps the component & the view in sync using Templates, data binding & change detection. All of them are bypassed when we update the DOM Directly.
DOM Manipulation works only in a browser. You will not able to use the App in other platforms like in a web worker, in server (by using Server-side rendering), in a mobile or desktop app, etc... where there is no browser.
The DOM APIs do not sanitize the data. Hence, it is possible to inject a script, thereby, opening our app an easy target for the XSS injection attack.

Change log

2022/02/22

Fix Exif rotation for new version of Chrome 79+
Native upload for Safari browser

2022/01/19

Implementing a built-in algorithm, looping several times, to reach a desired max size in Megabytes
Readme updates and docs in method signature directly

2022/01/04

Readme update
CI/CD with github action

2021/12/21

Update to Angular 13
Upload multiple file at once
Add support for resizing image size (compressFile() is now accepting maxWidth and maxHeight paramaters)
Cleanup types
Invalid image rejection
General refactoring

2021/11/14

Added support for max size

2020/11/18

Update to Angular 11
Fix upload for iOS
Expose getOrientation api publically

2019/07/01

Update to Angular 8 (angular 7 is enough)
Fix DOC_ORIENTATION import (not a required import)

2019/01/09

Since Angular 6 include its own packaging system, I no longer need my webpack config to build it.
Everything is working in angular 7 without complaint now (test app is on github)

2018/10/04

Adding Live example.
Everything is now working and tested but I will make some arrangement to the code in index.ts before submitting it again to npm, in order to make it more handy.

2017/12/06

Upload to Github
Need some fixes and tests to be use as a static library

Usage no npm install needed!