Drag and Drop

import { ResultSet, sqlite } from "https://esm.town/v/std/sqlite?v=6"; import { Hono } from "npm:hono@3"; await sqlite.batch([ // `DROP TABLE IF EXISTS draggable_circles`, `CREATE TABLE IF NOT EXISTS draggable_circles ( idx INTEGER NOT NULL UNIQUE, x REAL NOT NULL, y REAL NOT NULL )`, ]); // const circles = [ // { "x": 372.1564948287251, "y": 467.31488912659233, "index": 0 }, // { "x": 383.03204910618865, "y": 409.3382384327329, "index": 1 }, // { "x": 276.12943550800577, "y": 206.43967315595253, "index": 2 }, // { "x": 332.11355889496815, "y": 99.81295018896702, "index": 3 }, // { "x": 281.6660037446992, "y": 268.44660700812955, "index": 4 }, // { "x": 478.1371051427014, "y": 155.1225458786182, "index": 5 }, // { "x": 562.1071796055135, "y": 249.0351695539056, "index": 6 }, // { "x": 361.2641058287132, "y": 256.52910153255004, "index": 7 }, // { "x": 421.6175146074128, "y": 424.18276199871326, "index": 8 }, // { "x": 321.24193621279403, "y": 407.59672549522344, "index": 9 }, // { "x": 191.660159711138, "y": 432.14191514382543, "index": 10 }, // { "x": 119.15993815756639, "y": 96.84634939589058, "index": 11 }, // { "x": 121.65490887696441, "y": 564.6775769550197, "index": 12 }, // { "x": 110.8157416379427, "y": 244.36858357746033, "index": 13 }, // { "x": 263.1779853877889, "y": 202.64154214241603, "index": 14 }, // { "x": 135.13227065644418, "y": 336.9982482747027, "index": 15 }, // { "x": 129.77166867674111, "y": 286.4481811355409, "index": 16 }, // { "x": 465.98646535831665, "y": 503.4452648259519, "index": 17 }, // { "x": 201.30560985313258, "y": 300.19885737204976, "index": 18 }, // { "x": 285.49861283238147, "y": 90.07963880167979, "index": 19 }, // ]; // circles.forEach(async (c) => { // await sqlite.execute({ sql: `INSERT INTO draggable_circles VALUES (?, ?, ?)`, args: [c.index, c.x, c.y] }); // }); function parseResultSet(row: ResultSet): T[] { return row.rows.map((r) => Object.fromEntries(r.map((c, i) => [row.columns[i], c]))) as T[]; } type Circle = { x: number; y: number; idx: number; }; const getCircles = async () => { return parseResultSet(await sqlite.execute("select * from draggable_circles")); }; function diffCircles(array1: Circle[], array2: Circle[]): Circle[] { const changes: Circle[] = []; const map1 = new Map(array1.map(row => [row.idx, row])); const map2 = new Map(array2.map(row => [row.idx, row])); for (const [idx, row1] of map1) { const row2 = map2.get(idx); if (row2 && (row1.x !== row2.x || row1.y !== row2.y)) { changes.push(row2); } } return changes; } const clientCode = () => { const height = 600; const width = 600; const radius = 32; const svg = d3.select("svg"); const drag = (() => { function dragstarted() { d3.select(this).attr("stroke", "black"); } function dragged(event, d) { d3.select(this).raise().attr("cx", d.x = event.x).attr("cy", d.y = event.y); } function dragended() { const x = d3.select(this).attr("cx"); const y = d3.select(this).attr("cy"); fetch(`/update?x=${x}&y=${y}&i=${d3.select(this).attr("idx")}`, { method: "post" }); d3.select(this).attr("stroke", null); } return d3.drag() .on("start", dragstarted) .on("drag", dragged) .on("end", dragended); })(); window.circleObjects = svg.selectAll("circle") .data(circles) .join("circle") .attr("cx", d => d.x) .attr("cy", d => d.y) .attr("idx", d => d.idx) .attr("r", radius) .attr("fill", d => d3.schemeCategory10[d.idx % 10]) .call(drag) .on("click", clicked); function clicked(event, d) { if (event.defaultPrevented) return; // dragged d3.select(this).transition() .attr("fill", "black") .attr("r", radius * 2) .transition() .attr("r", radius) .attr("fill", d3.schemeCategory10[d.idx % 10]); } const eventSource = new EventSource(`/update-stream`); eventSource.onmessage = (event) => { JSON.parse(event.data).forEach((c: Circle) => { window.circleObjects.filter(d => d.idx === c.idx).transition().duration(100).attr("cx", c.x).attr("cy", c.y); }); }; }; const app = new Hono(); app.get("/", async (c) => { const circles = await getCircles(); return new Response( ` Drag and Drop `, { headers: { "Content-Type": "text/html" } }, ); }); app.post("/update", async (c) => { await sqlite.execute({ sql: "UPDATE draggable_circles SET x = ?, y = ? WHERE idx = ?", args: [c.req.query("x"), c.req.query("y"), c.req.query("i")], }); return new Response(JSON.stringify(true)); }); app.get("/update-stream", async (c) => { let cancelled = false; let circles = await getCircles(); const body = new ReadableStream({ async start(controller) { const write = (str) => { controller.enqueue(new TextEncoder().encode( "data: " + JSON.stringify(str) + "\n\n", )); }; while (!cancelled) { let newCircles = await getCircles(); let changed = diffCircles(circles, newCircles); if (changed.length > 0) { circles = newCircles; write(changed); } await new Promise(resolve => setTimeout(resolve, 500)); } controller.close(); }, cancel() { cancelled = true; }, }); return new Response(body, { headers: { "Content-Type": "text/event-stream" } }); }); export default app.fetch;

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