|
| 1 | +"use strict"; |
| 2 | + |
| 3 | +(function () { |
| 4 | + const params = new URLSearchParams(window.location.search); |
| 5 | + var socket = io(); |
| 6 | + var canvas = document.getElementsByClassName("whiteboard")[0]; |
| 7 | + var colors = document.getElementsByClassName("color"); |
| 8 | + var context = canvas.getContext("2d"); |
| 9 | + |
| 10 | + var current = { |
| 11 | + color: "black", |
| 12 | + }; |
| 13 | + var drawing = false; |
| 14 | + |
| 15 | + canvas.addEventListener("mousedown", onMouseDown, false); |
| 16 | + canvas.addEventListener("mouseup", onMouseUp, false); |
| 17 | + canvas.addEventListener("mouseout", onMouseUp, false); |
| 18 | + canvas.addEventListener("mousemove", throttle(onMouseMove, 10), false); |
| 19 | + |
| 20 | + //Touch support for mobile devices |
| 21 | + canvas.addEventListener("touchstart", onMouseDown, false); |
| 22 | + canvas.addEventListener("touchend", onMouseUp, false); |
| 23 | + canvas.addEventListener("touchcancel", onMouseUp, false); |
| 24 | + canvas.addEventListener("touchmove", throttle(onMouseMove, 10), false); |
| 25 | + |
| 26 | + for (var i = 0; i < colors.length; i++) { |
| 27 | + colors[i].addEventListener("click", onColorUpdate, false); |
| 28 | + } |
| 29 | + |
| 30 | + socket.on("drawing", onDrawingEvent); |
| 31 | + |
| 32 | + window.addEventListener("resize", onResize, false); |
| 33 | + onResize(); |
| 34 | + |
| 35 | + function drawLine(x0, y0, x1, y1, color, emit) { |
| 36 | + context.beginPath(); |
| 37 | + context.moveTo(x0, y0); |
| 38 | + context.lineTo(x1, y1); |
| 39 | + context.strokeStyle = color; |
| 40 | + context.lineWidth = 2; |
| 41 | + context.stroke(); |
| 42 | + context.closePath(); |
| 43 | + |
| 44 | + if (!emit) { |
| 45 | + return; |
| 46 | + } |
| 47 | + var w = canvas.width; |
| 48 | + var h = canvas.height; |
| 49 | + |
| 50 | + socket.emit("drawing", { |
| 51 | + x0: x0 / w, |
| 52 | + y0: y0 / h, |
| 53 | + x1: x1 / w, |
| 54 | + y1: y1 / h, |
| 55 | + color: color, |
| 56 | + }); |
| 57 | + } |
| 58 | + |
| 59 | + function onMouseDown(e) { |
| 60 | + drawing = true; |
| 61 | + current.x = e.clientX || e.touches[0].clientX; |
| 62 | + current.y = e.clientY || e.touches[0].clientY; |
| 63 | + } |
| 64 | + |
| 65 | + function onMouseUp(e) { |
| 66 | + if (!drawing) { |
| 67 | + return; |
| 68 | + } |
| 69 | + drawing = false; |
| 70 | + drawLine( |
| 71 | + current.x, |
| 72 | + current.y, |
| 73 | + e.clientX || e.touches[0].clientX, |
| 74 | + e.clientY || e.touches[0].clientY, |
| 75 | + current.color, |
| 76 | + true, |
| 77 | + ); |
| 78 | + } |
| 79 | + |
| 80 | + function onMouseMove(e) { |
| 81 | + if (!drawing) { |
| 82 | + return; |
| 83 | + } |
| 84 | + drawLine( |
| 85 | + current.x, |
| 86 | + current.y, |
| 87 | + e.clientX || e.touches[0].clientX, |
| 88 | + e.clientY || e.touches[0].clientY, |
| 89 | + current.color, |
| 90 | + true, |
| 91 | + ); |
| 92 | + current.x = e.clientX || e.touches[0].clientX; |
| 93 | + current.y = e.clientY || e.touches[0].clientY; |
| 94 | + } |
| 95 | + |
| 96 | + function onColorUpdate(e) { |
| 97 | + current.color = e.target.className.split(" ")[1]; |
| 98 | + } |
| 99 | + |
| 100 | + // limit the number of events per second |
| 101 | + function throttle(callback, delay) { |
| 102 | + var previousCall = new Date().getTime(); |
| 103 | + return function () { |
| 104 | + var time = new Date().getTime(); |
| 105 | + |
| 106 | + if (time - previousCall >= delay) { |
| 107 | + previousCall = time; |
| 108 | + callback.apply(null, arguments); |
| 109 | + } |
| 110 | + }; |
| 111 | + } |
| 112 | + |
| 113 | + function onDrawingEvent(data) { |
| 114 | + var w = canvas.width; |
| 115 | + var h = canvas.height; |
| 116 | + drawLine(data.x0 * w, data.y0 * h, data.x1 * w, data.y1 * h, data.color); |
| 117 | + } |
| 118 | + |
| 119 | + // make the canvas fill its parent |
| 120 | + function onResize() { |
| 121 | + canvas.width = window.innerWidth; |
| 122 | + canvas.height = window.innerHeight; |
| 123 | + } |
| 124 | +})(); |
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