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| 1 | +<!DOCTYPE html> |
| 2 | +<html lang="en"> |
| 3 | +<head> |
| 4 | + <meta charset="UTF-8"> |
| 5 | + <title>HTML5 Canvas</title> |
| 6 | +</head> |
| 7 | +<body> |
| 8 | +<canvas id="draw" width="800" height="800"></canvas> |
| 9 | +<script> |
| 10 | +const canvas = document.querySelector('#draw'); |
| 11 | +const ctx = canvas.getContext('2d'); |
| 12 | +canvas.width = window.innerWidth; |
| 13 | +canvas.height = window.innerHeight; |
| 14 | +ctx.strokeStyle = '#BADA55'; |
| 15 | +ctx.lineJoin = 'round'; |
| 16 | +ctx.lineCap = 'round'; |
| 17 | +ctx.lineWidth = 50; |
| 18 | + |
| 19 | +let isDrawing = true; |
| 20 | +let lastX = 0; |
| 21 | +let lastY = 0; |
| 22 | +let hue = 0; |
| 23 | +let direction = true; |
| 24 | + |
| 25 | +function draw(e){ |
| 26 | + if(!isDrawing) return; |
| 27 | + let lineX = e.offsetX; |
| 28 | + let lineY = e.offsetY; |
| 29 | + ctx.strokeStyle = `hsl(${hue},100%,50%)`; |
| 30 | + ctx.beginPath(); |
| 31 | + ctx.moveTo(lastX,lastY); |
| 32 | + ctx.lineTo(lineX,lineY); |
| 33 | + ctx.stroke(); |
| 34 | + [lastX,lastY] = [e.offsetX,e.offsetY]; |
| 35 | + hue++; |
| 36 | + hue %= 361; |
| 37 | + if(direction){ |
| 38 | + ctx.lineWidth--; |
| 39 | + }else{ |
| 40 | + ctx.lineWidth++; |
| 41 | + } |
| 42 | + // if(ctx.lineWidth<=1){ |
| 43 | + // direction = false; |
| 44 | + // }else if(ctx.lineWidth > 50){ |
| 45 | + // direction = true; |
| 46 | + // } |
| 47 | + |
| 48 | + if (ctx.lineWidth >= 50 || ctx.lineWidth <= 1) { |
| 49 | + direction = !direction; |
| 50 | + } |
| 51 | + console.log(ctx.lineWidth); |
| 52 | + // hue = (hue++)%360; //ERROR! |
| 53 | + // if(hue > 360){ |
| 54 | + // hue = 0; |
| 55 | + // } |
| 56 | +} |
| 57 | + |
| 58 | +canvas.addEventListener('mousemove',draw,false); |
| 59 | +canvas.addEventListener('mousedown',(e) => { |
| 60 | + [lastX,lastY] = [e.offsetX,e.offsetY]; |
| 61 | + isDrawing = true; |
| 62 | +},false); |
| 63 | +canvas.addEventListener('mouseup',() => { isDrawing = false;},false); |
| 64 | +canvas.addEventListener('mouseover',() => { isDrawing = false;},false); |
| 65 | +</script> |
| 66 | + |
| 67 | +<style> |
| 68 | + html, body { |
| 69 | + margin:0; |
| 70 | + } |
| 71 | +</style> |
| 72 | + |
| 73 | +</body> |
| 74 | +</html> |
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