Export my own function in opencv.js

,
1

I tried to use template matching in opencv.js (node.js environment)

test.js

const { matchTemplate } = require('./matchTemplate.js')
matchTemplate()
matchTemplate()
matchTemplate()
matchTemplate()
matchTemplate()

matchTemplate.js

const sharp = require('sharp')
function loadOpenCV() {
	return new Promise((resolve) => {
		global.Module = {
			onRuntimeInitialized: resolve
		}
		global.cv = require('./opencv.js')
	})
}

async function matchTemplate() {
	await loadOpenCV()
	const src = await readImageSharp('./images/fullscreen/000.PNG')
	const templ = await readImageSharp('./images/tiles/16.PNG')
	const dst = new cv.Mat()
	const mask = new cv.Mat()
	cv.matchTemplate(src, templ, dst, cv.TM_CCOEFF_NORMED, mask)
	const result = cv.minMaxLoc(dst, mask).maxVal
	for (const x of [src, templ, dst, mask]) {
		x.delete()
	}
	console.log(result)

	async function readImageSharp(input) {
		const { data, info } = await sharp(input)
			.ensureAlpha()
			.raw()
			.toBuffer({ resolveWithObject: true })
		const { width, height } = info
		return cv.matFromImageData({ data, width, height })
	}
}

module.exports = { matchTemplate }

when I run in command line

PS R:\mahjong\FYP22070> node test.js
1
PS R:\mahjong\FYP22070>

The function matchTemplate() is executed once only.

My question is, how can I export function matchTemplate(), so that I can execute in other JavaScript files for multiple times?

2

I’m not too familiar with javascript. you declared your own function to be async. don’t you need to call it specially, instead of like a regular function?