004_opencv-worker-js

This is webworker module for OpenCV.

opencv

Install

$ npm install \@dannadori/opencv-worker-js

API

generateOpenCVDefaultConfig: () => OpenCVConfig;
generateDefaultOpenCVParams: () => OpenCVOperationParams;

OpenCVWorkerManager
init(config: OpenCVConfig | null): Promise<unknown>;
predict(targetCanvas: HTMLCanvasElement, params?: OpenCVOperationParams): Promise<HTMLCanvasElement>;

Configuration and Parameter

export interface OpenCVConfig {
    browserType    : BrowserType;
    processOnLocal : boolean;
    workerPath     : string
}
export interface OpenCVOperationParams {
    type: OpenCVFunctionType;
    cannyParams: CannyParams | null;
    processWidth: number;
    processHeight: number;
}
export declare enum OpenCVFunctionType {
    Canny = 0,
    xxx = 1
}
export interface CannyParams {
    threshold1: number;
    threshold2: number;
    apertureSize: number;
    L2gradient: boolean;
}

Step by step

Create environment and install package

$ create-react-app demo/  --typescript
$ cd demo/
$ npm install
$ npm install @dannadori/opencv-worker-js

Add source image to public.

In this time, the name is "srcImage.jpg"

Edit src/App.tsx

Sample code is here.

import React from 'react';
import './App.css';
import { OpenCVWorkerManager, generateOpenCVDefaultConfig, generateDefaultOpenCVParams } from '@dannadori/opencv-worker-js'

class App extends React.Component{

  manager = new OpenCVWorkerManager()
  config = generateOpenCVDefaultConfig()
  params = generateDefaultOpenCVParams()

  srcCanvas = document.createElement("canvas")
  dstCanvas = document.createElement("canvas")

  componentDidMount = () =>{
    document.getRootNode().lastChild!.appendChild(this.srcCanvas)
    document.getRootNode().lastChild!.appendChild(this.dstCanvas)
    const srcImage = document.createElement("img")
    srcImage.onload = () =>{
      this.manager.init(this.config).then(()=>{
        this.srcCanvas.getContext("2d")!.drawImage(
          srcImage, 0, 0, this.srcCanvas.width, this.dstCanvas.height)
        return this.manager.predict(this.srcCanvas, this.params)
      }).then((res)=>{
        console.log(res)
        this.dstCanvas.getContext("2d")!.drawImage(res, 0, 0, this.dstCanvas.width, this.dstCanvas.height)
      })
    }
    srcImage.src = "./srcImage.jpg"
  }

  render = ()=>{
    return (
      <div className="App">
      </div>
    );
  }
}

export default App;

build and start

$ npm run start