84 lines
2.8 KiB
JavaScript
84 lines
2.8 KiB
JavaScript
"use strict";
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(() => {
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const drawElement = document.getElementById("drawDiv");
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if (!drawElement) {
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throw new Error("canvas not found");
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}
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const emitter = mitt();
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let drawing = false;
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let previous = null;
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const socket = initSocket("/draw/ws");
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const serializeDraw = ({ from, to }) => `${from.x},${from.y},${to.x},${to.y}`;
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const deserializeDraw = (message) => {
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const parts = message.split(",");
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return {
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from: { x: Number(parts[0]), y: Number(parts[1]) },
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to: { x: Number(parts[2]), y: Number(parts[3]) },
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};
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};
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emitter.on("mouseDraw", (e) => sendMessage(e));
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const sendMessage = (e) => socket.send(serializeDraw(e));
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const mouseDown = () => {
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drawing = true;
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previous = null;
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};
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const mouseUp = () => {
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drawing = false;
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};
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const mouseMove = (e) => {
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if (!drawing)
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return;
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if (previous) {
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emitter.emit("mouseDraw", {
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from: previous,
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to: { x: e.offsetX, y: e.offsetY },
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});
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}
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previous = { x: e.offsetX, y: e.offsetY };
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};
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const touchMove = (e) => {
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e.preventDefault();
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mouseMove({
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offsetX: e.touches[0].clientX - drawElement.offsetLeft,
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offsetY: e.touches[0].clientY - drawElement.offsetTop,
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});
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};
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drawElement.addEventListener("mousedown", mouseDown);
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drawElement.addEventListener("mouseup", mouseUp);
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drawElement.addEventListener("mousemove", mouseMove);
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drawElement.addEventListener("touchstart", mouseDown);
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drawElement.addEventListener("touchend", mouseUp);
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drawElement.addEventListener("touchmove", touchMove);
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const receiveCanvas = document.getElementById("receiveCanvas");
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const recCtx = receiveCanvas?.getContext("2d");
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if (!recCtx || !receiveCanvas) {
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throw new Error("canvas not found");
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}
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const render = (data) => {
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const { from, to } = data;
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if (recCtx.strokeStyle != "white") {
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recCtx.lineWidth = 2;
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recCtx.lineCap = "round";
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recCtx.strokeStyle = "white";
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}
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recCtx.beginPath();
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recCtx.moveTo(from.x, from.y);
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recCtx.lineTo(to.x, to.y);
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recCtx.closePath();
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recCtx.stroke();
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};
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emitter.on("mouseDraw", render);
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emitter.on("netDraw", render);
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socket.addMessageListener((data) => {
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if (data === "ping" || data.startsWith("pong"))
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return;
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emitter.emit("netDraw", deserializeDraw(data));
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});
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const resizeObserver = new ResizeObserver((entries) => {
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const entry = entries.at(0);
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receiveCanvas.height = entry?.contentRect.height ?? 500;
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receiveCanvas.width = entry?.contentRect.width ?? 500;
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});
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resizeObserver.observe(drawElement);
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})();
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