ngx-scanner-text

ngx-scanner-text

This Angular language library is built for optical character recognition from images provided as urls.
The core is based on Tesseract, a powerful optical character recognition (OCR) engine that supports over 100 languages.
This demo codesandbox, github.

Installation

npm install ngx-scanner-text@<version> --save

Usage

import { NgxScannerTextModule } from "ngx-scanner-text";

@NgModule({
    imports: [NgxScannerTextModule],
})
export class AppModule {}

<ngx-scanner-text #scanner="scanner" [configs]="configs" (event)="onData($event)"></ngx-scanner-text>

<pre>
  <textarea cols="80" rows="6">{{ scanner?.logger$ | async | json }}</textarea>
  <textarea cols="80" rows="9">{{ text }}</textarea>
</pre>

Models

export interface Configs {
  src: string;
  color: string;
  isAuto: boolean;
  isImage: boolean;
  languages: string[];
  jobId?: string;
  output?: Partial<OutputFormats>;
  options?: Partial<RecognizeOptions>;
};

export interface Scheduler {
  addWorker(worker: Worker): string;
  addJob(
    action: 'recognize',
    ...args: Parameters<Worker['recognize']>
  ): Promise<RecognizeResult>;
  addJob(
    action: 'detect',
    ...args: Parameters<Worker['detect']>
  ): Promise<DetectResult>;
  terminate(): Promise<any>;
  getQueueLen(): number;
  getNumWorkers(): number;
}

export interface Worker {
  load(jobId?: string): Promise<ConfigResult>;
  writeText(path: string, text: string, jobId?: string): Promise<ConfigResult>;
  readText(path: string, jobId?: string): Promise<ConfigResult>;
  removeText(path: string, jobId?: string): Promise<ConfigResult>;
  FS(method: string, args: any[], jobId?: string): Promise<ConfigResult>;
  loadLanguage(langs?: string | Lang[], jobId?: string): Promise<ConfigResult>;
  initialize(
    langs?: string | Lang[],
    oem?: OEM,
    config?: string | Partial<InitOptions>,
    jobId?: string
  ): Promise<ConfigResult>;
  setParameters(
    params: Partial<WorkerParams>,
    jobId?: string
  ): Promise<ConfigResult>;
  getImage(type: imageType): string;
  recognize(
    image: ImageLike,
    options?: Partial<RecognizeOptions>,
    output?: Partial<OutputFormats>,
    jobId?: string
  ): Promise<RecognizeResult>;
  detect(image: ImageLike, jobId?: string): Promise<DetectResult>;
  terminate(jobId?: string): Promise<ConfigResult>;
  getPDF(
    title?: string,
    textonly?: boolean,
    jobId?: string
  ): Promise<GetPDFResult>;
}

export interface Lang {
  code: string;
  data: unknown;
}

export interface InitOptions {
  load_system_dawg: string;
  load_freq_dawg: string;
  load_unambig_dawg: string;
  load_punc_dawg: string;
  load_number_dawg: string;
  load_bigram_dawg: string;
}

export type LoggerMessage = {
  jobId: string;
  progress: number;
  status: string;
  userJobId: string;
  workerId: string;
};

export interface WorkerOptions {
  corePath: string;
  langPath: string;
  cachePath: string;
  dataPath: string;
  workerPath: string;
  cacheMethod: string;
  workerBlobURL: boolean;
  gzip: boolean;
  logger: (arg: LoggerMessage) => void;
  errorHandler: (arg: any) => void;
}

export interface WorkerParams {
  tessedit_ocr_engine_mode: OEM;
  tessedit_pageseg_mode: PSM;
  tessedit_char_whitelist: string;
  preserve_interword_spaces: string;
  user_defined_dpi: string;
  tessjs_create_hocr: string;
  tessjs_create_tsv: string;
  tessjs_create_box: string;
  tessjs_create_unlv: string;
  tessjs_create_osd: string;
}

export interface OutputFormats {
  text: boolean;
  blocks: boolean;
  layoutBlocks: boolean;
  hocr: boolean;
  tsv: boolean;
  box: boolean;
  unlv: boolean;
  osd: boolean;
  pdf: boolean;
  imageColor: boolean;
  imageGrey: boolean;
  imageBinary: boolean;
  debug: boolean;
}

export interface RecognizeOptions {
  rectangle: Rectangle;
  pdfTitle: string;
  pdfTextOnly: boolean;
  rotateAuto: boolean;
  rotateRadians: number;
}

export interface ConfigResult {
  jobId: string;
  data: any;
}

export interface RecognizeResult {
  jobId: string;
  data: Page;
}

export interface GetPDFResult {
  jobId: string;
  data: number[];
}

export interface DetectResult {
  jobId: string;
  data: DetectData;
}

export interface DetectData {
  tesseract_script_id: number | null;
  script: string | null;
  script_confidence: number | null;
  orientation_degrees: number | null;
  orientation_confidence: number | null;
}

export interface Rectangle {
  left: number;
  top: number;
  width: number;
  height: number;
}

export enum OEM {
  TESSERACT_ONLY,
  LSTM_ONLY,
  TESSERACT_LSTM_COMBINED,
  DEFAULT,
}

export enum PSM {
  OSD_ONLY = '0',
  AUTO_OSD = '1',
  AUTO_ONLY = '2',
  AUTO = '3',
  SINGLE_COLUMN = '4',
  SINGLE_BLOCK_VERT_TEXT = '5',
  SINGLE_BLOCK = '6',
  SINGLE_LINE = '7',
  SINGLE_WORD = '8',
  CIRCLE_WORD = '9',
  SINGLE_CHAR = '10',
  SPARSE_TEXT = '11',
  SPARSE_TEXT_OSD = '12',
  RAW_LINE = '13',
}

export const enum imageType {
  COLOR = 0,
  GREY = 1,
  BINARY = 2,
}

export type ImageLike =
  | string
  | HTMLImageElement
  | HTMLCanvasElement
  | HTMLVideoElement
  | CanvasRenderingContext2D
  | File
  | Blob
  | ImageData
  | any;

export interface Block {
  paragraphs: Paragraph[];
  text: string;
  confidence: number;
  baseline: Baseline;
  bbox: Bbox;
  blocktype: string;
  polygon: any;
  page: Page;
  lines: Line[];
  words: Word[];
  symbols: Symbol[];
}

export interface Baseline {
  x0: number;
  y0: number;
  x1: number;
  y1: number;
  has_baseline: boolean;
}

export interface Bbox {
  x0: number;
  y0: number;
  x1: number;
  y1: number;
}

export interface Line {
  words: Word[];
  text: string;
  confidence: number;
  baseline: Baseline;
  bbox: Bbox;
  paragraph: Paragraph;
  block: Block;
  page: Page;
  symbols: Symbol[];
}

export interface Paragraph {
  lines: Line[];
  text: string;
  confidence: number;
  baseline: Baseline;
  bbox: Bbox;
  is_ltr: boolean;
  block: Block;
  page: Page;
  words: Word[];
  symbols: Symbol[];
}

export interface Symbol {
  choices: Choice[];
  image: any;
  text: string;
  confidence: number;
  baseline: Baseline;
  bbox: Bbox;
  is_superscript: boolean;
  is_subscript: boolean;
  is_dropcap: boolean;
  word: Word;
  line: Line;
  paragraph: Paragraph;
  block: Block;
  page: Page;
}

export interface Choice {
  text: string;
  confidence: number;
}

export interface Word {
  symbols: Symbol[];
  choices: Choice[];
  text: string;
  confidence: number;
  baseline: Baseline;
  bbox: Bbox;
  is_numeric: boolean;
  in_dictionary: boolean;
  direction: string;
  language: string;
  is_bold: boolean;
  is_italic: boolean;
  is_underlined: boolean;
  is_monospace: boolean;
  is_serif: boolean;
  is_smallcaps: boolean;
  font_size: number;
  font_id: number;
  font_name: string;
  line: Line;
  paragraph: Paragraph;
  block: Block;
  page: Page;
}

export interface Page {
  blocks: Block[] | null;
  confidence: number;
  lines: Line[];
  oem: string;
  osd: string;
  paragraphs: Paragraph[];
  psm: string;
  symbols: Symbol[];
  text: string;
  version: string;
  words: Word[];
  hocr: string | null;
  tsv: string | null;
  box: string | null;
  unlv: string | null;
  sd: string | null;
  imageColor: string | null;
  imageGrey: string | null;
  imageBinary: string | null;
  rotateRadians: number | null;
  pdf: number[] | null;
}

Support versions

Support versions
Angular 16	1.0.4
Angular 14	1.0.3

Author Information

Author Information
Author	DaiDH
Phone	[phone]
Country	Vietnam

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MIT License. Copyright (c) 2022 DaiDH