91 lines
2.8 KiB
JavaScript
91 lines
2.8 KiB
JavaScript
const sharp = require('sharp');
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const canvas = require('canvas');
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const crypto = require('crypto');
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const randint = (min, max) => { return crypto.randomInt(max) + min };
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/** @param {import('fastify').FastifyRequest} req */
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const getSettings = (req) => {
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const q = req.query;
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const settings = {
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// Width and height are ratio numbers; actual width & height is calculated from text length & padding
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width: q.width ?? 3,
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height: q.height ?? 1,
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padding: q.padding ?? 20,
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format: q.format ?? 'png',
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dpi: q.dpi ?? 250
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};
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for (const key in settings) {
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if (['format'].indexOf(key) !== -1) continue;
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settings[key] = parseInt(settings[key]);
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}
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return settings;
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}
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const get_size = (ratio, dpi, txtlen, padding) => {
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return {
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width: Math.floor((ratio[0] * dpi * 0.12) + (txtlen * dpi * 0.08)) + (padding * 2),
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height: Math.floor(ratio[1] * dpi * 0.2) + (padding * 2)
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}
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}
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/** @param {import('fastify').FastifyInstance} fastify */
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module.exports = (fastify) => {
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fastify.get('/captcha/v1/:text', async (req, res) => {
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const text = req.params.text;
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const settings = getSettings(req);
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const size = get_size([settings.width, settings.height], settings.dpi, text.length, settings.padding);
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console.log(size)
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console.log(settings)
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let pic = (await sharp({
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create: {
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width: size.width,
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height: size.height,
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channels: 4,
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background: { r: 0, g: 0, b: 0, alpha: 0 }
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}
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}));
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pic.composite([
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{
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input: {
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text: {
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text: text,
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font: 'Arial',
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dpi: settings.dpi,
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rgba: true
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}
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},
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blend: 'over',
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gravity: 0
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}
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]);
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const textpic = await pic
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.ensureAlpha()
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.toFormat('png', { compressionLevel: 6 })
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.toBuffer();
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const draw = canvas.createCanvas(size.width, size.height);
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const ctx = draw.getContext('2d');
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ctx.drawImage(await canvas.loadImage(textpic), 0, 0, size.width, size.height);
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const strokes = randint(25, 40);
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for (let i = 0; i != strokes; i++) {
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ctx.strokeStyle = `rgba(0,0,0,${10})`;
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ctx.beginPath();
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ctx.bezierCurveTo(randint(0, size.width), randint(0, size.height), randint(0, size.width), randint(0, size.height), randint(0, size.width), randint(0, size.height));
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ctx.stroke();
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}
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ctx.bezierCurveTo(20, 20, 20, 30, 70, 25);
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ctx.stroke();
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res.header('Content-Type', 'png');
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return draw.toBuffer();
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})
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} |