Ngx-document-scanner NPM

Ngx Document Scanner

An Angular component for cropping and enhancing images of documents, for implementation on a mobile or desktop app.
It uses a WASM build of OpenCV to manipulate images, to achieve near-native performance. Note that there are a few extra steps required to configure the component other than installing the package from npm.

Live Demo

View a live demo here

Installation & Setup

install the package via npm

npm install ngx-document-scanner --save

the UI is based on @angular/material, if you don't have it installed:

ng add @angular/material

choose 'yes' when prompted if you wish to add angular animations as it is needed for some of the components.

Configure OpenCV

copy the opencv.js files to your assets folder (or any other folder). you can build the files yourself (instructions on the OpenCV site), or download them from this package's repository. both opencv.js & opencv_js.wasm need to placed in the same folder.

import the package to your app.module. you'll need to configure the location of the open cv files.

import {OpenCVConfig} from 'ngx-document-scanner';
import {NgxDocumentScannerModule} from 'ngx-document-scanner';

// set the location of the OpenCV files
const openCVConfig: OpenCVConfig = {
  openCVDirPath: '/assets/opencv'  
};

@NgModule({ imports: 
  [NgxDocumentScannerModule.forRoot(openCVConfig)],
  bootstrap: [AppComponent]  
})
export class AppModule { }

Usage

add component to template and bind to inputs and outputs.

<ngx-doc-scanner 
     *ngIf="image"
     [file]="image"
     [config]="config">
     (editResult)="editResult($event)"
     (exitEditor)="exitEditor($event)"
     (error)="onError($event)"
     (processing)="editorState($event)"
</ngx-doc-scanner>

set configuration options. for example:

config: DocScannerConfig = {  
    editorBackgroundColor: '#fafafa', 
    buttonThemeColor: 'primary',  
    cropToolColor: '#ff4081',  
    cropToolShape: 'circle',
    exportImageIcon: 'cloud_download'  
};

Component I\O

Inputs

input	type	description
file	`File`	sets an image for editing
config	`DocScannerConfig`	configuration object for the component. see section dedicated to te config object.

Outputs

output	type	description
error	`EventEmitter<any>`	fires on error
editResult	`EventEmitter<Blob>`	fires when the users submits the image
exitEditor	`EventEmitter<any>`	fires when the user exits the editor
processing	`EventEmitter<boolean>`	fires true when the editor is prcessing or loading\parsing the OpenCV module.

Configuration Object

optional configuration values that can be passed to the component.

import {DocScannerConfig} form 'ngx-document-scanner'
config: DocScannerConfig = {
    ....
}

property	type	description
buttonThemeColor	"primary" \| "warn" \| "accent"	material design theme color name for the buttons on the component
cropToolColor	`string`	color of the crop tool (points and connecting lines)
cropToolDimensions	`{width: number; height: nubmer;}`	width and height of the crop tool points
cropToolLineWeight	`number`	weight of the crop tool's connecting lines
cropToolShape	`'rect' \| 'circle'`	shape of the crop tool points
editorBackgroundColor	`string`	background color of the main editor div
editorDimensions	an object of css keys value pairs	css properties for the main editor div
exportImageIcon	`string`	icon for the button that completes the editing and emits the edited image.
extraCss	an object of css keys value pairs	css that will be added to the main div of the editor component
maxImageDimensions	`{width: number; height: nubmer;}`	max dimensions of oputput image. if set to zero will not resize the image.
maxPreviewWidth	`number`	max width of the preview pane