dow/server/static/dow-emulator.js

/* eslint-disable @typescript-eslint/no-unused-vars */
/** @type {HTMLCanvasElement} */
const $canvas = document.getElementById('canvas')

const TYPES = {
	TEXT: 0,
	LINE: 1,
	CIRCLE: 2,
	CIRCLE_FILL: 3,
	RECT: 4,
	RECT_FILL: 5,
}

const ALIGN = {
	START: 0,
	CENTER: 1,
	END: 2,
}

const FONTS = {
	0: '24px FreeSans',
	1: '48px FreeSans',
	2: 'bold 124px "Fira Code"',
	3: '18px FreeSans',
}

/**
 * @param {{ x: number; y: number; t: number; c?: number; va?: number; ha?: number; f?: number; x2?: number; y2?: number; w?: number; h?: number; r?: number }[]} data
 */
function render(data) {
	const ctx = $canvas.getContext('2d')

	if (!ctx) {
		throw new Error('Canvas 2D context is not available')
	}

	ctx.imageSmoothingEnabled = false
	ctx.clearRect(0, 0, $canvas.width * 2, $canvas.height * 2)
	ctx.textBaseline = 'alphabetic'
	ctx.fillStyle = '#222'
	ctx.strokeStyle = '#222'

	for (const item of data) {
		switch (item.t) {
			case TYPES.TEXT: {
				const content = item.c
				const x = item.x
				const y = item.y
				const verticalAlign = item.va ?? 0
				const horizontalAlign = item.ha ?? 0
				const font = item.f ?? 0

				ctx.font = FONTS[font]

				const measured = ctx.measureText(content)

				let xx = x
				let yy = y

				switch (verticalAlign) {
					case ALIGN.START:
						yy = y + measured.actualBoundingBoxAscent
						break
					case ALIGN.CENTER:
						yy = y + measured.actualBoundingBoxAscent / 2
						break
					case ALIGN.END:
						yy = y
						break
				}

				switch (horizontalAlign) {
					case ALIGN.START:
						xx = x
						break
					case ALIGN.CENTER:
						xx = x - measured.width / 2
						break
					case ALIGN.END:
						xx = x - measured.width
						break
				}

				ctx.fillText(content, Math.round(xx), Math.round(yy))

				break
			}

			case TYPES.LINE: {
				const x = item.x
				const y = item.y
				const x2 = item.x2
				const y2 = item.y2

				ctx.moveTo(x, y)
				ctx.lineTo(x2, y2)
				ctx.stroke()

				break
			}

			case TYPES.CIRCLE: {
				const x = item.x
				const y = item.y
				const radius = item.r

				ctx.beginPath()
				ctx.arc(x, y, radius, 0, 2 * Math.PI)
				ctx.stroke()

				break
			}

			case TYPES.CIRCLE_FILL: {
				const x = item.x
				const y = item.y
				const radius = item.r

				ctx.beginPath()
				ctx.arc(x, y, radius, 0, 2 * Math.PI)
				ctx.fill()

				break
			}

			case TYPES.RECT: {
				const x = item.x
				const y = item.y
				const w = item.x2
				const h = item.y2

				ctx.strokeRect(x, y, w, h)

				break
			}

			case TYPES.RECT_FILL: {
				const x = item.x
				const y = item.y
				const w = item.x2
				const h = item.y2

				ctx.fillRect(x, y, w, h)

				break
			}
		}
	}
}

const WIDTH = 648
const HEIGHT = 480

const hours = new Date().getHours().toString().padStart(2, '0')
const minutes = new Date().getMinutes().toString().padStart(2, '0')

setInterval(() => {
	fetch('/api/dow').then((r) => r.json().then((data) => render(data)))
}, 1000)

render([
	{
		x: Math.round(WIDTH / 2),
		y: 20,
		t: TYPES.TEXT,
		c: `...`,
		va: ALIGN.START,
		ha: ALIGN.CENTER,
		f: 2,
	},
])