ngx-pica

ngx-pica is an Angular 5 module to resize images files in browser using pica - high quality image resize in browser.

Install

1. Add ngx-pica module as dependency to your project.

$ npm install ngx-pica --save

2. Include NgxPicaModule into your main AppModule or in module where you will use it.

// app.module.ts
import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { NgxPicaModule } from 'ngx-pica';

@NgModule({
  imports: [
    BrowserModule,
    NgxPicaModule
  ],
  declarations: [ AppComponent ],
  exports: [ AppComponent ]
})
export class AppModule {}

Services

• NgxPicaService - Manipulate images using pica - high quality image resize in browser
• NgxPicaImageService - Supplementary services to help you work with images

NgxPicaService Methods

.resizeImages(files: File[], width: number, height: number, options?: NgxPicaResizeOptionsInterface): Observable<File>

This method resize an array of images doing it sequentially to optimize CPU and memory use.

• files:[] - Array of images to resize
• width - Width to be resized (px)
• height - Height to be resized (px)
• options - Based on pica - resize options, we've also added aspect ratio options:
  • keepAspectRatio - Set true to ensure the aspect ratio of the image is maintained as it get resized
  • forceMinDimensions - Set true to ensure the dimensions of image resized will be greater than width and height values defined

The Observable receives a next on every file that has been resized. If something goes wrong the Observable receive an error.

All errors are wrapped by NgxPicaErrorInterface.

.resizeImage(file: File, width: number, height: number, options?: NgxPicaResizeOptionsInterface): Observable<File>

Same as above but only takes one file instead of an array of files.

.compressImages(files: File[], sizeInMB: number): Observable<File>

This method compress an array of images doing it sequentially to optimize CPU and memory use.

• files:[] - Array of images to resize
• sizeInMB - File size in MegaBytes

The Observable receives a next on every file that has been resized. If something goes wrong the Observable receive an error.

All errors are wrapped by NgxPicaErrorInterface.

.compressImage(file: File, sizeInMB: number): Observable<File>

Same as above but only takes one file instead of an array of files.

NgxPicaImageService Methods

.isImage(file: File): boolean

This method check if a file is an image or not

Data Structures

export interface AspectRatioOptions {
    keepAspectRatio: boolean;
    forceDimensions?: boolean;
}

export interface NgxPicaResizeOptionsInterface {
    aspectRatio?: AspectRatioOptions;
    quality?: number;
    alpha?: boolean;
    unsharpAmount?: number;
    unsharpRadius?: number;
    unsharpThreshold?: number;
}

export enum NgxPicaErrorType {
    NO_FILES_RECEIVED = 'NO_FILES_RECEIVED',
    CANVAS_CONTEXT_IDENTIFIER_NOT_SUPPORTED = 'CANVAS_CONTEXT_IDENTIFIER_NOT_SUPPORTED',
    NOT_BE_ABLE_TO_COMPRESS_ENOUGH = 'NOT_BE_ABLE_TO_COMPRESS_ENOUGH'
}

export interface NgxPicaErrorInterface {
    err: NgxPicaErrorType;
    file?: File;
}

Example

import { Component, EventEmitter } from '@angular/core';
import { NgxPicaService } from 'ngx-pica';

@Component({
  selector: 'app-home',
  template: `
      <img *ngFor="let image of images" [src]="image" />
  
      <input type="file" [attr.accept]="image/*" multiple
             (change)="handleFiles($event)">
  `
})
export class AppHomeComponent {
    images: File[] = [];
    
    constructor(private _ngxPicaService: NgxPicaService) {
    
    }
    
    public handleFiles(event: any) {
        const files: File[] = event.target.files;
        
        this._ngxPicaService.resizeImages(files, 1200, 880)
            .subscribe((imageResized: File) => {
                let reader: FileReader = new FileReader();
                
                reader.addEventListener('load', (event: any) => {
                    this.images.push(event.target.result);
                }, false);
                
                reader.readAsDataURL(imageResized);
                
            }, (err: NgxPicaErrorInterface) => {
                throw err.err;
            });
    }