101 lines
3.5 KiB
JavaScript
101 lines
3.5 KiB
JavaScript
// @ts-check
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const assert = require("assert").strict
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const {pipeline} = require("stream").promises
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const sharp = require("sharp")
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const {GIFrame} = require("giframe")
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const utils = require("./utils")
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const fetch = require("node-fetch").default
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const streamMimeType = require("stream-mime-type")
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const SIZE = 48
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const RESULT_WIDTH = 400
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const IMAGES_ACROSS = Math.floor(RESULT_WIDTH / SIZE)
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/**
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* Composite a bunch of Matrix emojis into a kind of spritesheet image to upload to Discord.
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* @param {string[]} mxcs mxc URLs, in order
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* @returns {Promise<Buffer>} PNG image
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*/
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async function compositeMatrixEmojis(mxcs) {
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let buffers = await Promise.all(mxcs.map(async mxc => {
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const abortController = new AbortController()
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try {
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const url = utils.getPublicUrlForMxc(mxc)
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assert(url)
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/** @type {import("node-fetch").Response} res */
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// If it turns out to be a GIF, we want to abandon the connection without downloading the whole thing.
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// If we were using connection pooling, we would be forced to download the entire GIF.
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// So we set no agent to ensure we are not connection pooling.
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// @ts-ignore the signal is slightly different from the type it wants (still works fine)
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const res = await fetch(url, {agent: false, signal: abortController.signal})
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const {stream, mime} = await streamMimeType.getMimeType(res.body)
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assert(["image/png", "image/jpeg", "image/webp", "image/gif"].includes(mime), `Mime type ${mime} is impossible for emojis`)
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if (mime === "image/png" || mime === "image/jpeg" || mime === "image/webp") {
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/** @type {{info: sharp.OutputInfo, buffer: Buffer}} */
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const result = await new Promise((resolve, reject) => {
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const transformer = sharp()
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.resize(SIZE, SIZE, {fit: "contain", background: {r: 0, g: 0, b: 0, alpha: 0}})
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.png({compressionLevel: 0})
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.toBuffer((err, buffer, info) => {
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/* c8 ignore next */
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if (err) return reject(err)
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resolve({info, buffer})
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})
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pipeline(
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stream,
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transformer
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)
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})
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return result.buffer
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} else if (mime === "image/gif") {
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const giframe = new GIFrame(0)
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stream.on("data", chunk => {
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giframe.feed(chunk)
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})
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const frame = await giframe.getFrame()
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const buffer = await sharp(frame.pixels, {raw: {width: frame.width, height: frame.height, channels: 4}})
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.resize(SIZE, SIZE, {fit: "contain", background: {r: 0, g: 0, b: 0, alpha: 0}})
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.png({compressionLevel: 0})
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.toBuffer({resolveWithObject: true})
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return buffer.data
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}
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} finally {
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abortController.abort()
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}
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}))
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// Calculate the size of the final composited image
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const totalWidth = Math.min(buffers.length, IMAGES_ACROSS) * SIZE
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const imagesDown = Math.ceil(buffers.length / IMAGES_ACROSS)
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const totalHeight = imagesDown * SIZE
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const comp = []
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let left = 0, top = 0
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for (const buffer of buffers) {
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if (Buffer.isBuffer(buffer)) {
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// Composite the current buffer into the sprite sheet
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comp.push({left, top, input: buffer})
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// The next buffer should be placed one slot to the right
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left += SIZE
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// If we're out of space to fit the entire next buffer there, wrap to the next line
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if (left + SIZE > RESULT_WIDTH) {
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left = 0
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top += SIZE
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}
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}
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}
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const output = await sharp({create: {width: totalWidth, height: totalHeight, channels: 4, background: {r: 0, g: 0, b: 0, alpha: 0}}})
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.composite(comp)
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.png()
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.toBuffer({resolveWithObject: true})
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return output.data
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}
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module.exports.compositeMatrixEmojis = compositeMatrixEmojis
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